diff --git a/lib/honeybadger/backend/base.rb b/lib/honeybadger/backend/base.rb
index 7016902b..c2c692f0 100644
--- a/lib/honeybadger/backend/base.rb
+++ b/lib/honeybadger/backend/base.rb
@@ -4,7 +4,7 @@
 
 require 'honeybadger/logging'
 
-require 'honeybadger/checkin'
+require 'honeybadger/check_in'
 
 module Honeybadger
   module Backend
@@ -111,59 +111,59 @@ def track_deployment(payload)
         notify(:deploys, payload)
       end
 
-      # Get checkin by id
+      # Get check_in by id
       # @example
-      #   backend.get_checkin('1234', 'ajdja")
+      #   backend.get_check_in('1234', 'ajdja")
       #
       # @param [String] project_id The unique project id
       # @param [String] id The unique check_in id
       # @raise NotImplementedError
-      def get_checkin(project_id, id)
+      def get_check_in(project_id, id)
         raise NotImplementedError, 'must define #get_checkin on subclass'
       end
 
       # Get checkins by project
       # @example
-      #   backend.get_checkins('1234')
+      #   backend.get_check_ins('1234')
       #
       # @param [String] project_id The unique project id
       # @raise NotImplementedError
-      def get_checkins(project_id)
+      def get_check_ins(project_id)
         raise NotImplementedError, 'must define #get_checkins on subclass'
       end
 
-      # Create checkin on project
+      # Create check_in on project
       # @example
-      #   backend.create_checkin('1234', checkin)
+      #   backend.create_check_in('1234', check_in)
       #
       # @param [String] project_id The unique project id
-      # @param [Checkin] data A Checkin object encapsulating the config
+      # @param [CheckIn] data A CheckIn object encapsulating the config
       # @raise NotImplementedError
-      def create_checkin(project_id, data)
-        raise NotImplementedError, 'must define #create_checkin on subclass'
+      def create_check_in(project_id, data)
+        raise NotImplementedError, 'must define #create_check_in on subclass'
       end
 
-      # Update checkin on project
+      # Update check_in on project
       # @example
-      #   backend.update_checkin('1234', 'eajaj', checkin)
+      #   backend.update_check_in('1234', 'eajaj', check_in)
       #
       # @param [String] project_id The unique project id
       # @param [String] id The unique check_in id
-      # @param [Checkin] data A Checkin object encapsulating the config
+      # @param [CheckIn] data A CheckIn object encapsulating the config
       # @raise NotImplementedError
-      def update_checkin(project_id, id, data)
-        raise NotImplementedError, 'must define #update_checkin on subclass'
+      def update_check_in(project_id, id, data)
+        raise NotImplementedError, 'must define #update_check_in on subclass'
       end
 
-      # Delete checkin
+      # Delete check_in
       # @example
-      #   backend.delete_checkin('1234', 'eajaj')
+      #   backend.delete_check_in('1234', 'eajaj')
       #
       # @param [String] project_id The unique project id
       # @param [String] id The unique check_in id
       # @raise NotImplementedError
-      def delete_checkin(project_id, id)
-        raise NotImplementedError, 'must define #delete_checkin on subclass'
+      def delete_check_in(project_id, id)
+        raise NotImplementedError, 'must define #delete_check_in on subclass'
       end
 
       private
diff --git a/lib/honeybadger/backend/server.rb b/lib/honeybadger/backend/server.rb
index 182a1887..93f86ea4 100644
--- a/lib/honeybadger/backend/server.rb
+++ b/lib/honeybadger/backend/server.rb
@@ -16,12 +16,11 @@ class Server < Base
 
       CHECK_IN_ENDPOINT = '/v1/check_in'.freeze
 
-
       HTTP_ERRORS = Util::HTTP::ERRORS
 
       def initialize(config)
         @http = Util::HTTP.new(config)
-        # for checkin config sync
+        # for check_in config sync
         @personal_auth_token = config.get(:personal_auth_token)
         super
       end
@@ -52,93 +51,93 @@ def check_in(id)
 
 
       #
-      ##### Checkin Crud methods
+      ##### CheckIn Crud methods
       #
 
-      # Get checkin by id
+      # Get check_in by id
       # @example
-      #   backend.get_checkin('1234', 'ajdja")
+      #   backend.get_check_in('1234', 'ajdja")
       #
       # @param [String] project_id The unique project id
       # @param [String] id The unique check_in id
-      # @returns [Checkin] or nil if checkin is not found
-      # @raises CheckinSyncError on error
+      # @returns [CheckIn] or nil if check_in is not found
+      # @raises CheckInSyncError on error
 
-      def get_checkin(project_id, id)
+      def get_check_in(project_id, id)
         response = Response.new(@http.get("/v2/projects/#{project_id}/check_ins/#{id}", personal_auth_headers))
         if response.success?
-          return Checkin.from_remote(project_id, JSON.parse(response.body))
+          return CheckIn.from_remote(project_id, JSON.parse(response.body))
         else
           if response.code == 404
             return nil
           end
         end
-        raise CheckinSyncError.new "Fetching Checkin failed (Code: #{response.code}) #{response.body}"
+        raise CheckInSyncError.new "Fetching CheckIn failed (Code: #{response.code}) #{response.body}"
       end
 
-      # Get checkins by project
+      # Get check_ins by project
       # @example
-      #   backend.get_checkins('1234')
+      #   backend.get_check_ins('1234')
       #
       # @param [String] project_id The unique project id
-      # @returns [Array<Checkin>] All checkins for this project
-      # @raises CheckinSyncError on error
-      def get_checkins(project_id)
+      # @returns [Array<CheckIn>] All checkins for this project
+      # @raises CheckInSyncError on error
+      def get_check_ins(project_id)
         response = Response.new(@http.get("/v2/projects/#{project_id}/check_ins", personal_auth_headers))
         if response.success?
-          all_checkins = JSON.parse(response.body)["results"]
-          return all_checkins.map{|cfg| Checkin.from_remote(project_id, cfg) }
+          all_check_ins = JSON.parse(response.body)["results"]
+          return all_check_ins.map{|cfg| CheckIn.from_remote(project_id, cfg) }
         end
-        raise CheckinSyncError.new "Fetching Checkins failed (Code: #{response.code}) #{response.body}"
+        raise CheckInSyncError.new "Fetching CheckIns failed (Code: #{response.code}) #{response.body}"
       end
 
-      # Create checkin on project
+      # Create check_in on project
       # @example
-      #   backend.create_checkin('1234', checkin)
+      #   backend.create_check_in('1234', check_in)
       #
       # @param [String] project_id The unique project id
-      # @param [Checkin] data A Checkin object encapsulating the config
-      # @returns [Checkin] A checkin object containing the id
-      # @raises CheckinSyncError on error
-      def create_checkin(project_id, data)
-        response = Response.new(@http.post("/v2/projects/#{project_id}/check_ins", data.to_json, personal_auth_headers))
+      # @param [CheckIn] check_in_config A CheckIn object encapsulating the config
+      # @returns [CheckIn] A CheckIn object additionally containing the id
+      # @raises CheckInSyncError on error
+      def create_check_in(project_id, check_in_config)
+        response = Response.new(@http.post("/v2/projects/#{project_id}/check_ins", check_in_config.to_json, personal_auth_headers))
         if response.success?
-          return Checkin.from_remote(project_id, JSON.parse(response.body))
+          return CheckIn.from_remote(project_id, JSON.parse(response.body))
         end
-        raise CheckinSyncError.new "Creating Checkin failed (Code: #{response.code}) #{response.body}"
+        raise CheckInSyncError.new "Creating CheckIn failed (Code: #{response.code}) #{response.body}"
       end
 
-      # Update checkin on project
+      # Update check_in on project
       # @example
-      #   backend.update_checkin('1234', 'eajaj', checkin)
+      #   backend.update_check_in('1234', 'eajaj', check_in)
       #
       # @param [String] project_id The unique project id
       # @param [String] id The unique check_in id
-      # @param [Checkin] data A Checkin object encapsulating the config
-      # @returns [Checkin] updated Checkin object
-      # @raises CheckinSyncError on error
-      def update_checkin(project_id, id, data)
-        response = Response.new(@http.put("/v2/projects/#{project_id}/check_ins/#{id}", data.to_json, personal_auth_headers))
+      # @param [CheckIn] check_in_config A CheckIn object encapsulating the config
+      # @returns [CheckIn] updated CheckIn object
+      # @raises CheckInSyncError on error
+      def update_check_in(project_id, id, check_in_config)
+        response = Response.new(@http.put("/v2/projects/#{project_id}/check_ins/#{id}", check_in_config.to_json, personal_auth_headers))
         if response.success?
-          return Checkin.from_remote(project_id, JSON.parse(response.body))
+          return CheckIn.from_remote(project_id, JSON.parse(response.body))
         end
-        raise CheckinSyncError.new "Updating Checkin failed (Code: #{response.code}) #{response.body}"
+        raise CheckInSyncError.new "Updating CheckIn failed (Code: #{response.code}) #{response.body}"
       end
 
-      # Delete checkin
+      # Delete check_in
       # @example
-      #   backend.delete_checkin('1234', 'eajaj')
+      #   backend.delete_check_in('1234', 'eajaj')
       #
       # @param [String] project_id The unique project id
       # @param [String] id The unique check_in id
       # @returns [Boolean] true if deletion was successful
-      # @raises CheckinSyncError on error
-      def delete_checkin(project_id, id)
+      # @raises CheckInSyncError on error
+      def delete_check_in(project_id, id)
         response = Response.new(@http.delete("/v2/projects/#{project_id}/check_ins/#{id}", personal_auth_headers))
         if response.success?
           return true
         end
-        raise CheckinSyncError.new "Deleting Checkin failed (Code: #{response.code}) #{response.body}"
+        raise CheckInSyncError.new "Deleting CheckIn failed (Code: #{response.code}) #{response.body}"
       end
 
       private
diff --git a/lib/honeybadger/backend/test.rb b/lib/honeybadger/backend/test.rb
index e3911d70..da561616 100644
--- a/lib/honeybadger/backend/test.rb
+++ b/lib/honeybadger/backend/test.rb
@@ -42,102 +42,102 @@ def check_in(id)
         super
       end
 
-      def self.checkin_configs
-        @checkin_configs ||= {}
+      def self.check_in_configs
+        @check_in_configs ||= {}
       end
 
-      def checkin_configs
-        self.class.checkin_configs
+      def check_in_configs
+        self.class.check_in_configs
       end
 
-      # Set checkin by id, only for use in tests
+      # Set check_in by id, only for use in tests
       # @example
-      #   backend.set_checkin('1234', 'ajdja', checkin)
+      #   backend.set_checkin('1234', 'ajdja', check_in)
       #
       # @param [String] project_id The unique project id
       # @param [String] id The unique check_in id
-      # @param [Checkin] data Checkin object with config
+      # @param [CheckIn] data CheckIn object with config
       def set_checkin(project_id, id, data)
-        self.checkin_configs[project_id] = self.checkin_configs[project_id] || {}
-        self.checkin_configs[project_id][id] = data
+        self.check_in_configs[project_id] = self.check_in_configs[project_id] || {}
+        self.check_in_configs[project_id][id] = data
       end
 
-      # Get checkin by id
+      # Get check_in by id
       # @example
-      #   backend.get_checkin('1234', 'ajdja")
+      #   backend.get_check_in('1234', 'ajdja")
       #
       # @param [String] project_id The unique project id
       # @param [String] id The unique check_in id
-      # @returns [Checkin] or nil if checkin is not found
-      def get_checkin(project_id, id)
-        self.checkin_configs ||= {}
-        self.checkin_configs[project_id]&.[](id)
+      # @returns [CheckIn] or nil if check_in is not found
+      def get_check_in(project_id, id)
+        self.check_in_configs ||= {}
+        self.check_in_configs[project_id]&.[](id)
       end
 
       # Get checkins by project
       # @example
-      #   backend.get_checkins('1234')
+      #   backend.get_check_ins('1234')
       #
       # @param [String] project_id The unique project id
-      # @returns [Array<Checkin>] All checkins for this project
-      def get_checkins(project_id)
-        self.checkin_configs ||= {}
-        self.checkin_configs[project_id] = self.checkin_configs[project_id] || {}
-        return [] if self.checkin_configs[project_id].empty?
-        self.checkin_configs[project_id].values
+      # @returns [Array<CheckIn>] All checkins for this project
+      def get_check_ins(project_id)
+        self.check_in_configs ||= {}
+        self.check_in_configs[project_id] = self.check_in_configs[project_id] || {}
+        return [] if self.check_in_configs[project_id].empty?
+        self.check_in_configs[project_id].values
       end
 
-      # Create checkin on project
+      # Create check_in on project
       # @example
-      #   backend.create_checkin('1234', checkin)
+      #   backend.create_check_in('1234', check_in)
       #
       # @param [String] project_id The unique project id
-      # @param [Checkin] data A Checkin object encapsulating the config
-      # @returns [Checkin] A checkin object containing the id
-      def create_checkin(project_id, data)
-        self.checkin_configs ||= {}
-        self.checkin_configs[project_id] = self.checkin_configs[project_id] || {}
-        id = self.checkin_configs[project_id].length + 1
+      # @param [CheckIn] data A CheckIn object encapsulating the config
+      # @returns [CheckIn] A check_in object containing the id
+      def create_check_in(project_id, data)
+        self.check_in_configs ||= {}
+        self.check_in_configs[project_id] = self.check_in_configs[project_id] || {}
+        id = self.check_in_configs[project_id].length + 1
         loop do
-          break unless self.checkin_configs[project_id].has_key?(id)
+          break unless self.check_in_configs[project_id].has_key?(id)
           id += 1
         end
         id = id.to_s
         data.id = id
-        self.checkin_configs[project_id][id] = data
+        self.check_in_configs[project_id][id] = data
         data
       end
 
-      # Update checkin on project
+      # Update check_in on project
       # @example
-      #   backend.update_checkin('1234', 'eajaj', checkin)
+      #   backend.update_check_in('1234', 'eajaj', check_in)
       #
       # @param [String] project_id The unique project id
       # @param [String] id The unique check_in id
-      # @param [Checkin] data A Checkin object encapsulating the config
-      # @returns [Checkin] updated Checkin object
-      def update_checkin(project_id, id, data)
-        self.checkin_configs ||= {}
-        if self.checkin_configs[project_id]&.[](id)
-          self.checkin_configs[project_id][id] = data
+      # @param [CheckIn] data A CheckIn object encapsulating the config
+      # @returns [CheckIn] updated CheckIn object
+      def update_check_in(project_id, id, data)
+        self.check_in_configs ||= {}
+        if self.check_in_configs[project_id]&.[](id)
+          self.check_in_configs[project_id][id] = data
           return data
         else
           raise "Update failed"
         end
       end
 
-      # Delete checkin
+      # Delete check_in
       # @example
-      #   backend.delete_checkin('1234', 'eajaj')
+      #   backend.delete_check_in('1234', 'eajaj')
       #
       # @param [String] project_id The unique project id
       # @param [String] id The unique check_in id
       # @returns [Boolean] true if deletion was successful
-      # @raises CheckinSyncError on error
-      def delete_checkin(project_id, id)
-        self.checkin_configs ||= {}
-        if self.checkin_configs[project_id]&.[](id)
-          self.checkin_configs[project_id].delete(id)
+      # @raises CheckInSyncError on error
+      def delete_check_in(project_id, id)
+        self.check_in_configs ||= {}
+        if self.check_in_configs[project_id]&.[](id)
+          self.check_in_configs[project_id].delete(id)
         else
           raise "Delete failed"
         end
diff --git a/lib/honeybadger/checkin.rb b/lib/honeybadger/check_in.rb
similarity index 59%
rename from lib/honeybadger/checkin.rb
rename to lib/honeybadger/check_in.rb
index 010d27b3..fad57c1f 100644
--- a/lib/honeybadger/checkin.rb
+++ b/lib/honeybadger/check_in.rb
@@ -1,34 +1,34 @@
 module Honeybadger
   class InvalidCheckinConfig < StandardError; end
-  class CheckinSyncError < StandardError; end
+  class CheckInSyncError < StandardError; end
   
-  class Checkin
+  class CheckIn
     attr_reader :project_id
     attr_accessor :name, :slug, :schedule_type, :report_period, :grace_period, :cron_schedule, :cron_timezone, :deleted, :id
     def self.from_config(config_entry)
       c = config_entry.transform_keys {|k| k.to_s }
       
-      checkin = self.new(c["project_id"], c["id"])
-      checkin.name = c["name"]
-      checkin.slug = c["slug"]
-      checkin.schedule_type = c["schedule_type"]
-      checkin.report_period = c["report_period"]
-      checkin.grace_period = c["grace_period"]
-      checkin.cron_schedule = c["cron_schedule"]
-      checkin.cron_timezone = c["cron_timezone"]
-      checkin
+      check_in = self.new(c["project_id"], c["id"])
+      check_in.name = c["name"]
+      check_in.slug = c["slug"]
+      check_in.schedule_type = c["schedule_type"]
+      check_in.report_period = c["report_period"]
+      check_in.grace_period = c["grace_period"]
+      check_in.cron_schedule = c["cron_schedule"]
+      check_in.cron_timezone = c["cron_timezone"]
+      check_in
     end
     
     def self.from_remote(project_id, data)
-      checkin = self.new(project_id, data["id"])
-      checkin.name = data["name"]
-      checkin.slug = data["slug"]
-      checkin.schedule_type = data["schedule_type"]
-      checkin.report_period = data["report_period"]
-      checkin.grace_period = data["grace_period"]
-      checkin.cron_schedule = data["cron_schedule"]
-      checkin.cron_timezone = data["cron_timezone"]
-      checkin
+      check_in = self.new(project_id, data["id"])
+      check_in.name = data["name"]
+      check_in.slug = data["slug"]
+      check_in.schedule_type = data["schedule_type"]
+      check_in.report_period = data["report_period"]
+      check_in.grace_period = data["grace_period"]
+      check_in.cron_schedule = data["cron_schedule"]
+      check_in.cron_timezone = data["cron_timezone"]
+      check_in
     end
 
     def initialize(project_id, id = nil)
@@ -60,8 +60,8 @@ def blank?(str)
     end
 
     def validate!
-      raise InvalidCheckinConfig.new('project_id is required for each checkin') if blank?(project_id)
-      raise InvalidCheckinConfig.new('name is required for each checkin') if blank?(name)
+      raise InvalidCheckinConfig.new('project_id is required for each check_in') if blank?(project_id)
+      raise InvalidCheckinConfig.new('name is required for each check_in') if blank?(name)
       raise InvalidCheckinConfig.new("#{name} schedule_type must be either 'simple' or 'cron'") unless ['simple', 'cron'].include? schedule_type
       if schedule_type == 'simple'
         raise InvalidCheckinConfig.new("#{name} report_period is required for simple checkins") if blank?(report_period)
@@ -70,14 +70,14 @@ def validate!
       end
     end
 
-    def update_from(checkin)
-      self.name = checkin.name
-      self.slug = checkin.slug
-      self.schedule_type = checkin.schedule_type
-      self.report_period = checkin.report_period
-      self.grace_period = checkin.grace_period
-      self.cron_schedule = checkin.cron_schedule
-      self.cron_timezone = checkin.cron_timezone
+    def update_from(check_in)
+      self.name = check_in.name
+      self.slug = check_in.slug
+      self.schedule_type = check_in.schedule_type
+      self.report_period = check_in.report_period
+      self.grace_period = check_in.grace_period
+      self.cron_schedule = check_in.cron_schedule
+      self.cron_timezone = check_in.cron_timezone
     end
 
     def deleted?
diff --git a/lib/honeybadger/cli/checkins.rb b/lib/honeybadger/cli/check_ins.rb
similarity index 93%
rename from lib/honeybadger/cli/checkins.rb
rename to lib/honeybadger/cli/check_ins.rb
index 021e135d..8039a211 100644
--- a/lib/honeybadger/cli/checkins.rb
+++ b/lib/honeybadger/cli/check_ins.rb
@@ -19,7 +19,7 @@ def initialize(options, args, config)
       def run
         config_sync_service = ConfigSyncService.new(@config)
         result = config_sync_service.sync_checkins
-        say("Checkin config synced", :green)
+        say("CheckIn config synced", :green)
       end
 
       private
diff --git a/lib/honeybadger/cli/main.rb b/lib/honeybadger/cli/main.rb
index 5a81beaf..56d3a7ca 100644
--- a/lib/honeybadger/cli/main.rb
+++ b/lib/honeybadger/cli/main.rb
@@ -4,7 +4,7 @@
 require 'honeybadger/cli/install'
 require 'honeybadger/cli/notify'
 require 'honeybadger/cli/test'
-require 'honeybadger/cli/checkins'
+require 'honeybadger/cli/check_ins'
 require 'honeybadger/config'
 require 'honeybadger/config/defaults'
 require 'honeybadger/ruby'
diff --git a/lib/honeybadger/config_sync_service.rb b/lib/honeybadger/config_sync_service.rb
index 79d6054e..2bb41a44 100644
--- a/lib/honeybadger/config_sync_service.rb
+++ b/lib/honeybadger/config_sync_service.rb
@@ -1,9 +1,9 @@
-require 'honeybadger/checkin'
+require 'honeybadger/check_in'
 module Honeybadger
   class ConfigSyncService
     def initialize(config)
       @config = config
-      @checkins_cache = nil
+      @check_ins_cache = nil
     end
 
     def sync_checkins
@@ -11,9 +11,9 @@ def sync_checkins
       return [] if checkin_configs.empty?
 
       checkins = checkin_configs.map do |cfg|
-        checkin = Checkin.from_config(cfg)
-        checkin.validate!
-        checkin
+        check_in = CheckIn.from_config(cfg)
+        check_in.validate!
+        check_in
       end
       created_or_updated = sync_existing_checkins(checkins)
       removed = sync_removed_checkins(checkins)
@@ -24,25 +24,25 @@ def sync_checkins
     private
 
     def get_checkin_by_name(project_id, name)
-      @checkins_cache ||= @config.backend.get_checkins(project_id)
-      @checkins_cache.find {|c| c.name == name }
+      @check_ins_cache ||= @config.backend.get_check_ins(project_id)
+      @check_ins_cache.find {|c| c.name == name }
     end
 
     def sync_existing_checkins(checkins = [])
       return [] if checkins.empty?
       result = []
-      checkins.each do |checkin|
-        remote_checkin = if checkin.id
-          @config.backend.get_checkin(checkin.project_id, checkin.id)
+      checkins.each do |check_in|
+        remote_checkin = if check_in.id
+          @config.backend.get_check_in(check_in.project_id, check_in.id)
         else
-          get_checkin_by_name(checkin.project_id, checkin.name)
+          get_checkin_by_name(check_in.project_id, check_in.name)
         end
         if remote_checkin
-          unless remote_checkin == checkin
-            result << @config.backend.update_checkin(checkin.project_id, remote_checkin.id, checkin)
+          unless remote_checkin == check_in
+            result << @config.backend.update_check_in(check_in.project_id, remote_checkin.id, check_in)
           end
         else
-          result << @config.backend.create_checkin(checkin.project_id, checkin)
+          result << @config.backend.create_check_in(check_in.project_id, check_in)
         end
       end
       result
@@ -53,17 +53,17 @@ def sync_removed_checkins(checkins)
       result = []
       project_ids = checkins.map{|ch| ch.project_id }.uniq
       project_ids.each do |prj_id|
-        @checkins_cache ||= @config.backend.get_checkins(prj_id)
+        @check_ins_cache ||= @config.backend.get_check_ins(prj_id)
 
         local_project_checkins = checkins.select {|c| c.project_id == prj_id }
-        to_remove = @checkins_cache.reject do |pc|
+        to_remove = @check_ins_cache.reject do |pc|
           local_project_checkins.find{|c| c.id == pc.id || c.name == pc.name }
         end
         to_remove.each do |ch|
           if ch.id.nil?
             ch = get_checkin_by_name(prj_id, ch.name)
           end
-          @config.backend.delete_checkin(prj_id, ch.id)
+          @config.backend.delete_check_in(prj_id, ch.id)
           ch.deleted = true
           result << ch
         end
diff --git a/spec/features/checkins_spec.rb b/spec/features/check_ins_spec.rb
similarity index 85%
rename from spec/features/checkins_spec.rb
rename to spec/features/check_ins_spec.rb
index 32ef8684..db532722 100644
--- a/spec/features/checkins_spec.rb
+++ b/spec/features/check_ins_spec.rb
@@ -1,14 +1,14 @@
 require 'honeybadger'
 
-feature "Running the checkins cli command" do
-  scenario "sync checkins" do
+feature "Running the check_ins cli command" do
+  scenario "sync check ins" do
     context "with config file" do
       let(:config_file_contents) { 
         {
           checkins: [
             {
               project_id: 'abcd',
-              name: "worker checkin",
+              name: "worker check in",
               schedule_type: "simple",
               report_period: "1 hour"
             }
@@ -25,7 +25,7 @@
 
       after { File.unlink(config_file) }
 
-      it "syncs checkin configuration" do
+      it "syncs check in configuration" do
         expect(run_command("honeybadger sync_checkins --personal-auth-token=abcd")).to be_successfully_executed
       end
     end
@@ -45,7 +45,7 @@
 
       after { File.unlink(config_file) }
 
-      it "does not sync checkin configuration if checkins are not configured in config file" do
+      it "does not sync check_in configuration if checkins are not configured in config file" do
         expect(run_command("honeybadger sync_checkins --personal-auth-token=abcd")).to_not be_successfully_executed
         expect(all_output).to match(/No checkins provided in config file/)
       end
diff --git a/spec/unit/honeybadger/backend/base_spec.rb b/spec/unit/honeybadger/backend/base_spec.rb
index 548706f0..eec9e33d 100644
--- a/spec/unit/honeybadger/backend/base_spec.rb
+++ b/spec/unit/honeybadger/backend/base_spec.rb
@@ -64,34 +64,34 @@
     end
   end
 
-  describe "checkin API methods" do
+  describe "check_in API methods" do
     describe "#get_checkin" do
       it "raises NotImplementedError" do
-        expect { subject.get_checkin('abcd', 'efgh') }.to raise_error NotImplementedError
+        expect { subject.get_check_in('abcd', 'efgh') }.to raise_error NotImplementedError
       end
     end
 
     describe "#get_checkins" do
       it "raises NotImplementedError" do
-        expect { subject.get_checkins('abcd') }.to raise_error NotImplementedError
+        expect { subject.get_check_ins('abcd') }.to raise_error NotImplementedError
       end
     end
 
-    describe "#create_checkin" do
+    describe "#create_check_in" do
       it "raises NotImplementedError" do
-        expect { subject.create_checkin('abcd', {}) }.to raise_error NotImplementedError
+        expect { subject.create_check_in('abcd', {}) }.to raise_error NotImplementedError
       end
     end
 
-    describe "#update_checkin" do
+    describe "#update_check_in" do
       it "raises NotImplementedError" do
-        expect { subject.update_checkin('abcd', 'efgh', {}) }.to raise_error NotImplementedError
+        expect { subject.update_check_in('abcd', 'efgh', {}) }.to raise_error NotImplementedError
       end
     end
 
-    describe "#delete_checkin" do
+    describe "#delete_check_in" do
       it "raises NotImplementedError" do
-        expect { subject.delete_checkin('abcd', 'efgh') }.to raise_error NotImplementedError
+        expect { subject.delete_check_in('abcd', 'efgh') }.to raise_error NotImplementedError
       end
     end
   end
diff --git a/spec/unit/honeybadger/backend/server_spec.rb b/spec/unit/honeybadger/backend/server_spec.rb
index d3ba9268..14ed4805 100644
--- a/spec/unit/honeybadger/backend/server_spec.rb
+++ b/spec/unit/honeybadger/backend/server_spec.rb
@@ -89,7 +89,7 @@ def notify_backend
         get_one = stub_request(:get, "https://api.honeybadger.io/v2/projects/1234/check_ins/5678").to_return({
           status: 200,
           body: {
-            name: "Test Checkin",
+            name: "Test CheckIn",
             slug: nil,
             schedule_type: "simple",
             report_period: "1 day",
@@ -99,25 +99,25 @@ def notify_backend
             id: "5678"
           }.to_json
         })
-        checkin = subject.get_checkin("1234", "5678")
-        expect(checkin).to be_a(Honeybadger::Checkin)
+        check_in = subject.get_check_in("1234", "5678")
+        expect(check_in).to be_a(Honeybadger::CheckIn)
         expect(get_one).to have_been_made
       end
 
       it "should return nil if it gets a 404" do
         get_one = stub_request(:get, "https://api.honeybadger.io/v2/projects/1234/check_ins/5678").to_return({status: 404})
-        checkin = subject.get_checkin("1234", "5678")
-        expect(checkin).to be_nil
+        check_in = subject.get_check_in("1234", "5678")
+        expect(check_in).to be_nil
         expect(get_one).to have_been_made
       end
     end
-    
+
     describe "#get_checkins" do
       it "should return an array of check ins" do
         get_all = stub_request(:get, "https://api.honeybadger.io/v2/projects/1234/check_ins").to_return({
           status: 200,
           body: {results: [{
-            name: "Test Checkin",
+            name: "Test CheckIn",
             slug: nil,
             schedule_type: "simple",
             report_period: "1 day",
@@ -127,20 +127,20 @@ def notify_backend
             id: "5678"
           }]}.to_json
         })
-        checkins = subject.get_checkins("1234")
+        checkins = subject.get_check_ins("1234")
         expect(checkins).to be_a(Array)
         expect(checkins.length).to eq(1)
-        expect(checkins.first).to be_a(Honeybadger::Checkin)
+        expect(checkins.first).to be_a(Honeybadger::CheckIn)
         expect(get_all).to have_been_made
       end
     end
 
-    describe "#create_checkin" do
-      it "should return checkin" do
+    describe "#create_check_in" do
+      it "should return check_in" do
         post_one = stub_request(:post, "https://api.honeybadger.io/v2/projects/1234/check_ins").to_return({
           status: 200,
           body: {
-            name: "Test Checkin",
+            name: "Test CheckIn",
             slug: nil,
             schedule_type: "simple",
             report_period: "1 day",
@@ -150,24 +150,24 @@ def notify_backend
             id: "5678"
           }.to_json
         })
-        checkin = Honeybadger::Checkin.from_config({
-          name: "Test Checkin",
+        check_in = Honeybadger::CheckIn.from_config({
+          name: "Test CheckIn",
           schedule_type: "simple",
           report_period: "1 day",
           grace_period: "3 hours"
         })
-        result = subject.create_checkin("1234", checkin)
-        expect(result).to be_a(Honeybadger::Checkin)
+        result = subject.create_check_in("1234", check_in)
+        expect(result).to be_a(Honeybadger::CheckIn)
         expect(post_one).to have_been_made
       end
     end
 
-    describe "#update_checkin" do
-      it "should return checkin" do
+    describe "#update_check_in" do
+      it "should return check_in" do
         put_one = stub_request(:put, "https://api.honeybadger.io/v2/projects/1234/check_ins/5678").to_return({
           status: 200,
           body: {
-            name: "Test Checkin",
+            name: "Test CheckIn",
             slug: nil,
             schedule_type: "simple",
             report_period: "2 days",
@@ -177,22 +177,22 @@ def notify_backend
             id: "5678"
           }.to_json
         })
-        checkin = Honeybadger::Checkin.from_config({
-          name: "Test Checkin",
+        check_in = Honeybadger::CheckIn.from_config({
+          name: "Test CheckIn",
           schedule_type: "simple",
           report_period: "2 days",
           grace_period: "3 hours"
         })
-        result = subject.update_checkin("1234", "5678", checkin)
-        expect(result).to be_a(Honeybadger::Checkin)
+        result = subject.update_check_in("1234", "5678", check_in)
+        expect(result).to be_a(Honeybadger::CheckIn)
         expect(put_one).to have_been_made
       end
     end
 
-    describe "#delete_checkin" do
+    describe "#delete_check_in" do
       it "should accept a delete" do
         delete_one = stub_request(:delete, "https://api.honeybadger.io/v2/projects/1234/check_ins/5678").to_return(status: 200)
-        result = subject.delete_checkin("1234", "5678")
+        result = subject.delete_check_in("1234", "5678")
         expect(result).to be_truthy
         expect(delete_one).to have_been_made
       end
diff --git a/spec/unit/honeybadger/backend/test_spec.rb b/spec/unit/honeybadger/backend/test_spec.rb
index 2af63b48..026b38a4 100644
--- a/spec/unit/honeybadger/backend/test_spec.rb
+++ b/spec/unit/honeybadger/backend/test_spec.rb
@@ -1,6 +1,6 @@
 require 'honeybadger/backend/test'
 require 'honeybadger/config'
-require 'honeybadger/checkin'
+require 'honeybadger/check_in'
 
 
 describe Honeybadger::Backend::Test do
@@ -48,107 +48,107 @@
     end
   end
 
-  context "checkin sync crud methods" do
+  context "check_in sync crud methods" do
     before do
-      Honeybadger::Backend::Test.checkin_configs.clear
+      Honeybadger::Backend::Test.check_in_configs.clear
     end
 
     describe "#set_checkin" do
       it "should set object on class" do
-        checkin = Honeybadger::Checkin.from_config({
+        check_in = Honeybadger::CheckIn.from_config({
           project_id: "1234",
-          name: "Test checkin",
+          name: "Test check_in",
           schedule_type: "simple",
           report_period: "1 hour"
         })
 
-        subject.set_checkin("1234", "5678", checkin)
-        expect(subject.checkin_configs["1234"]["5678"]).to eq(checkin)
+        subject.set_checkin("1234", "5678", check_in)
+        expect(subject.check_in_configs["1234"]["5678"]).to eq(check_in)
       end
     end
 
     describe "#get_checkin" do
-      it "should return nil if checkin does not exist" do
-        expect(subject.get_checkin("1234", "5678")).to be_nil
+      it "should return nil if check_in does not exist" do
+        expect(subject.get_check_in("1234", "5678")).to be_nil
       end
-      it "should return checkin if it exists" do
-        checkin = Honeybadger::Checkin.from_config({
+      it "should return check_in if it exists" do
+        check_in = Honeybadger::CheckIn.from_config({
           project_id: "1234",
-          name: "Test checkin",
+          name: "Test check_in",
           schedule_type: "simple",
           report_period: "1 hour"
         })
-        subject.set_checkin("1234", "5678", checkin)
-        expect(subject.get_checkin("1234", "5678")).to eq(checkin)
+        subject.set_checkin("1234", "5678", check_in)
+        expect(subject.get_check_in("1234", "5678")).to eq(check_in)
       end
     end
 
     describe "#get_checkins" do
-      it "should return empty array if no checkin exists" do
-        expect(subject.get_checkins("1234")).to be_empty
+      it "should return empty array if no check_in exists" do
+        expect(subject.get_check_ins("1234")).to be_empty
       end
-      it "should return array if checkin exists" do
-        checkin = Honeybadger::Checkin.from_config({
+      it "should return array if check_in exists" do
+        check_in = Honeybadger::CheckIn.from_config({
           project_id: "1234",
-          name: "Test checkin",
+          name: "Test check_in",
           schedule_type: "simple",
           report_period: "1 hour"
         })
-        subject.set_checkin("1234", "5678", checkin)
-        expect(subject.get_checkins("1234").first).to eq(checkin)
+        subject.set_checkin("1234", "5678", check_in)
+        expect(subject.get_check_ins("1234").first).to eq(check_in)
       end
     end
 
-    describe "#create_checkin" do
-      it "should create checkin and return it" do
-        checkin = Honeybadger::Checkin.from_config({
+    describe "#create_check_in" do
+      it "should create check_in and return it" do
+        check_in = Honeybadger::CheckIn.from_config({
           project_id: "1234",
-          name: "Test checkin",
+          name: "Test check_in",
           schedule_type: "simple",
           report_period: "1 hour"
         })
-        created = subject.create_checkin("1234", checkin)
+        created = subject.create_check_in("1234", check_in)
         expect(created.id).to_not be_nil
-        expect(subject.checkin_configs["1234"][created.id]).to_not be_nil
+        expect(subject.check_in_configs["1234"][created.id]).to_not be_nil
       end
     end
 
-    describe "#update_checkin" do
-      it "should update checkin and return it" do
-        checkin = Honeybadger::Checkin.from_config({
+    describe "#update_check_in" do
+      it "should update check_in and return it" do
+        check_in = Honeybadger::CheckIn.from_config({
           project_id: "1234",
-          name: "Test checkin",
+          name: "Test check_in",
           schedule_type: "simple",
           report_period: "1 hour"
         })
-        checkin_update = Honeybadger::Checkin.from_config({
+        checkin_update = Honeybadger::CheckIn.from_config({
           project_id: "1234",
-          name: "Test checkin",
+          name: "Test check_in",
           schedule_type: "simple",
           report_period: "2 hours"
         })
 
-        subject.set_checkin("1234", "5678", checkin)
-        updated = subject.update_checkin("1234", "5678", checkin_update)
+        subject.set_checkin("1234", "5678", check_in)
+        updated = subject.update_check_in("1234", "5678", checkin_update)
 
         expect(updated.report_period).to eq("2 hours")
-        expect(subject.checkin_configs["1234"]["5678"].report_period).to eq("2 hours")
+        expect(subject.check_in_configs["1234"]["5678"].report_period).to eq("2 hours")
       end
     end
 
-    describe "#delete_checkin" do
-      it "should update checkin and return it" do
-        checkin = Honeybadger::Checkin.from_config({
+    describe "#delete_check_in" do
+      it "should update check_in and return it" do
+        check_in = Honeybadger::CheckIn.from_config({
           project_id: "1234",
-          name: "Test checkin",
+          name: "Test check_in",
           schedule_type: "simple",
           report_period: "1 hour"
         })
-        subject.set_checkin("1234", "5678", checkin)
-        expect(subject.checkin_configs["1234"]["5678"]).to_not be_nil
+        subject.set_checkin("1234", "5678", check_in)
+        expect(subject.check_in_configs["1234"]["5678"]).to_not be_nil
 
-        expect(subject.delete_checkin("1234", "5678")).to be_truthy
-        expect(subject.checkin_configs["1234"]["5678"]).to be_nil
+        expect(subject.delete_check_in("1234", "5678")).to be_truthy
+        expect(subject.check_in_configs["1234"]["5678"]).to be_nil
       end
     end
   end
diff --git a/spec/unit/honeybadger/config_sync_service_spec.rb b/spec/unit/honeybadger/config_sync_service_spec.rb
index bbf49a16..d00a2bbd 100644
--- a/spec/unit/honeybadger/config_sync_service_spec.rb
+++ b/spec/unit/honeybadger/config_sync_service_spec.rb
@@ -2,7 +2,7 @@
 require 'honeybadger/backend/server'
 require 'honeybadger/config'
 require 'honeybadger/config_sync_service'
-require 'honeybadger/checkin'
+require 'honeybadger/check_in'
 
 describe Honeybadger::ConfigSyncService do
   let(:config) { Honeybadger::Config.new(logger: NULL_LOGGER, api_key: 'abc123', backend: 'test') }
@@ -10,10 +10,10 @@
 
   subject { described_class.new(config) }
 
-  context "sync checkin configs" do
+  context "sync check_in configs" do
 
     before {
-      config.backend.checkin_configs.clear
+      config.backend.check_in_configs.clear
     }
 
     it "syncs with empty array" do
@@ -22,34 +22,34 @@
       expect(result).to be_empty
     end
 
-    it "syncs with good checkin by id, unchanged" do
-      config.set(:checkins, [{project_id: '1234', id: '5678', name: 'Main Web App Checkin', schedule_type: 'simple', report_period: '1 hour'}])
-      config.backend.set_checkin("1234", "5678", Honeybadger::Checkin.from_config({
+    it "syncs with good check_in by id, unchanged" do
+      config.set(:checkins, [{project_id: '1234', id: '5678', name: 'Main Web App CheckIn', schedule_type: 'simple', report_period: '1 hour'}])
+      config.backend.set_checkin("1234", "5678", Honeybadger::CheckIn.from_config({
         project_id: "1234",
         id: "5678",
-        name: "Main Web App Checkin", schedule_type: "simple", report_period: "1 hour",
+        name: "Main Web App CheckIn", schedule_type: "simple", report_period: "1 hour",
       }))
       result = subject.sync_checkins
       expect(result).to be_empty
     end
 
-    it "syncs with good checkin by name, unchanged" do
-      config.set(:checkins, [{project_id: '1234', name: 'Main Web App Checkin', schedule_type: 'simple', report_period: '1 hour'}])
-      config.backend.set_checkin("1234", "5678", Honeybadger::Checkin.from_config({
+    it "syncs with good check_in by name, unchanged" do
+      config.set(:checkins, [{project_id: '1234', name: 'Main Web App CheckIn', schedule_type: 'simple', report_period: '1 hour'}])
+      config.backend.set_checkin("1234", "5678", Honeybadger::CheckIn.from_config({
         project_id: "1234",
         id: "5678",
-        name: "Main Web App Checkin", slug: nil, schedule_type: "simple", report_period: "1 hour",
+        name: "Main Web App CheckIn", slug: nil, schedule_type: "simple", report_period: "1 hour",
       }))
       result = subject.sync_checkins
       expect(result).to be_empty
     end
 
-    it "syncs with good checkin by id, with changes" do
-      config.set(:checkins, [{project_id: '1234', id: '5678', name: 'Main Web App Checkin', schedule_type: 'simple', report_period: '2 hours'}])
-      config.backend.set_checkin("1234", "5678", Honeybadger::Checkin.from_config({
+    it "syncs with good check_in by id, with changes" do
+      config.set(:checkins, [{project_id: '1234', id: '5678', name: 'Main Web App CheckIn', schedule_type: 'simple', report_period: '2 hours'}])
+      config.backend.set_checkin("1234", "5678", Honeybadger::CheckIn.from_config({
         project_id: "1234",
         id: "5678",
-        name: "Main Web App Checkin", slug: nil, schedule_type: "simple", report_period: "1 hour",
+        name: "Main Web App CheckIn", slug: nil, schedule_type: "simple", report_period: "1 hour",
       }))
       result = subject.sync_checkins
 
@@ -57,8 +57,8 @@
       expect(result.first.id).to eq("5678")
     end
 
-    it "syncs with new checkin" do
-      new_project = {project_id: '1234', name: 'Main Web App Checkin', schedule_type: 'simple', report_period: '1 hour'}
+    it "syncs with new check_in" do
+      new_project = {project_id: '1234', name: 'Main Web App CheckIn', schedule_type: 'simple', report_period: '1 hour'}
       config.set(:checkins, [new_project])
 
       result = subject.sync_checkins
@@ -68,13 +68,13 @@
     end
 
     it "syncs with removed checkins" do
-      config.set(:checkins, [{project_id: '1234', id: "5678", name: 'Main Web App Checkin', schedule_type: 'simple', report_period: '1 hour'}])
-      config.backend.set_checkin("1234", "5678", Honeybadger::Checkin.from_config({
+      config.set(:checkins, [{project_id: '1234', id: "5678", name: 'Main Web App CheckIn', schedule_type: 'simple', report_period: '1 hour'}])
+      config.backend.set_checkin("1234", "5678", Honeybadger::CheckIn.from_config({
         project_id: "1234",
         id: "5678",
-        name: "Main Web App Checkin", slug: nil, schedule_type: "simple", report_period: "1 hour",
+        name: "Main Web App CheckIn", slug: nil, schedule_type: "simple", report_period: "1 hour",
       }))
-      config.backend.set_checkin("1234", "dele", Honeybadger::Checkin.from_config({
+      config.backend.set_checkin("1234", "dele", Honeybadger::CheckIn.from_config({
         project_id: "1234",
         id: "dele",
         name: "to be deleted", slug: nil, schedule_type: "simple", report_period: "1 hour",