diff --git a/.github/ISSUE_TEMPLATE/bug_report.yaml b/.github/ISSUE_TEMPLATE/bug_report.yaml
index 712d9aece38..ed0a886f9d3 100644
--- a/.github/ISSUE_TEMPLATE/bug_report.yaml
+++ b/.github/ISSUE_TEMPLATE/bug_report.yaml
@@ -10,7 +10,7 @@ body:
         repository. If there is a duplicate, please close your issue and add a comment
         to the existing issue instead.
 
-        Please also see [the FAQs and Troubleshooting](https://github.com/containerd/nerdctl/blob/master/docs/faq.md).
+        Please also see [the FAQs and Troubleshooting](https://github.com/containerd/nerdctl/blob/main/docs/faq.md).
 
   - type: textarea
     attributes:
diff --git a/.github/workflows/ghcr-image-build-and-publish.yml b/.github/workflows/ghcr-image-build-and-publish.yml
index 18f0074efbe..e7f101a17bb 100644
--- a/.github/workflows/ghcr-image-build-and-publish.yml
+++ b/.github/workflows/ghcr-image-build-and-publish.yml
@@ -7,7 +7,7 @@ name: Container Image Build
 
 on:
   push:
-    branches: [ master, main ]
+    branches: [ main ]
     # Publish semver tags as releases.
     tags: [ 'v*.*.*' ]
 
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index d98fb09c537..93c28cef877 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -3,7 +3,6 @@ name: test
 on:
   push:
     branches:
-      - master
       - main
       - 'release/**'
   pull_request:
diff --git a/README.md b/README.md
index 5277bca06a3..be839404885 100644
--- a/README.md
+++ b/README.md
@@ -177,7 +177,7 @@ Trivial:
 
 ## Similar tools
 
-- [`ctr`](https://github.com/containerd/containerd/tree/master/cmd/ctr): incompatible with Docker CLI, and not friendly to users.
+- [`ctr`](https://github.com/containerd/containerd/tree/main/cmd/ctr): incompatible with Docker CLI, and not friendly to users.
   Notably, `ctr` lacks the equivalents of the following nerdctl commands:
   - `nerdctl run -p <PORT>`
   - `nerdctl run --restart=always --net=bridge`
@@ -194,9 +194,9 @@ Trivial:
 ## Developer guide
 nerdctl is a containerd **non-core** sub-project, licensed under the [Apache 2.0 license](./LICENSE).
 As a containerd non-core sub-project, you will find the:
- * [Project governance](https://github.com/containerd/project/blob/master/GOVERNANCE.md),
+ * [Project governance](https://github.com/containerd/project/blob/main/GOVERNANCE.md),
  * [Maintainers](./MAINTAINERS),
- * and [Contributing guidelines](https://github.com/containerd/project/blob/master/CONTRIBUTING.md)
+ * and [Contributing guidelines](https://github.com/containerd/project/blob/main/CONTRIBUTING.md)
 
 information in our [`containerd/project`](https://github.com/containerd/project) repository.
 
diff --git a/cmd/nerdctl/client.go b/cmd/nerdctl/client.go
index 6d23b3ba89d..ea7f90e26ac 100644
--- a/cmd/nerdctl/client.go
+++ b/cmd/nerdctl/client.go
@@ -68,7 +68,7 @@ func newClient(cmd *cobra.Command, opts ...containerd.ClientOpt) (*containerd.Cl
 func newClientWithPlatform(cmd *cobra.Command, platform string, clientOpts ...containerd.ClientOpt) (*containerd.Client, context.Context, context.CancelFunc, error) {
 	if platform != "" {
 		if canExec, canExecErr := platformutil.CanExecProbably(platform); !canExec {
-			warn := fmt.Sprintf("Platform %q seems incompatible with the host platform %q. If you see \"exec format error\", see https://github.com/containerd/nerdctl/blob/master/docs/multi-platform.md",
+			warn := fmt.Sprintf("Platform %q seems incompatible with the host platform %q. If you see \"exec format error\", see https://github.com/containerd/nerdctl/blob/main/docs/multi-platform.md",
 				platform, platforms.DefaultString())
 			if canExecErr != nil {
 				logrus.WithError(canExecErr).Warn(warn)
diff --git a/cmd/nerdctl/create.go b/cmd/nerdctl/create.go
index d92cec9ea45..ac712c113cc 100644
--- a/cmd/nerdctl/create.go
+++ b/cmd/nerdctl/create.go
@@ -32,7 +32,7 @@ func newCreateCommand() *cobra.Command {
 		longHelp += "WARNING: `nerdctl create` is experimental on Windows and currently broken (https://github.com/containerd/nerdctl/issues/28)"
 	case "freebsd":
 		longHelp += "\n"
-		longHelp += "WARNING: `nerdctl create` is experimental on FreeBSD and currently requires `--net=none` (https://github.com/containerd/nerdctl/blob/master/docs/freebsd.md)"
+		longHelp += "WARNING: `nerdctl create` is experimental on FreeBSD and currently requires `--net=none` (https://github.com/containerd/nerdctl/blob/main/docs/freebsd.md)"
 	}
 	var createCommand = &cobra.Command{
 		Use:               "create [flags] IMAGE [COMMAND] [ARG...]",
diff --git a/cmd/nerdctl/image_encrypt.go b/cmd/nerdctl/image_encrypt.go
index 4758893603e..39ee30659f3 100644
--- a/cmd/nerdctl/image_encrypt.go
+++ b/cmd/nerdctl/image_encrypt.go
@@ -39,7 +39,7 @@ Example:
   nerdctl push example.com/foo:encrypted
 
 To run the encrypted image, put the private key file (mykey.pem) to /etc/containerd/ocicrypt/keys (rootful) or ~/.config/containerd/ocicrypt/keys (rootless).
-containerd before v1.4 requires extra configuration steps, see https://github.com/containerd/nerdctl/blob/master/docs/ocicrypt.md
+containerd before v1.4 requires extra configuration steps, see https://github.com/containerd/nerdctl/blob/main/docs/ocicrypt.md
 
 CAUTION: This command only encrypts image layers, but does NOT encrypt container configuration such as 'Env' and 'Cmd'.
 To see non-encrypted information, run 'nerdctl image inspect --mode=native --platform=PLATFORM example.com/foo:encrypted' .
diff --git a/cmd/nerdctl/ipfs_registry_serve.go b/cmd/nerdctl/ipfs_registry_serve.go
index f2ee91ff47d..51214d10fbf 100644
--- a/cmd/nerdctl/ipfs_registry_serve.go
+++ b/cmd/nerdctl/ipfs_registry_serve.go
@@ -80,7 +80,7 @@ func ipfsRegistryServeAction(cmd *cobra.Command, args []string) error {
 	} else {
 		ipfsClient, err = httpapi.NewLocalApi()
 		if err != nil {
-			return fmt.Errorf("error encountered, '%w', Please setup ipfs daemon, see https://github.com/containerd/nerdctl/blob/master/docs/ipfs.md", err)
+			return fmt.Errorf("error encountered, '%w', Please setup ipfs daemon, see https://github.com/containerd/nerdctl/blob/main/docs/ipfs.md", err)
 		}
 	}
 	h, err := ipfs.NewRegistry(ipfsClient, ipfs.RegistryOptions{
diff --git a/cmd/nerdctl/main.go b/cmd/nerdctl/main.go
index b8f6ea2077b..dc2a0b86142 100644
--- a/cmd/nerdctl/main.go
+++ b/cmd/nerdctl/main.go
@@ -197,8 +197,8 @@ func initRootCmdFlags(rootCmd *cobra.Command, tomlPath string) (*pflag.FlagSet,
 	rootCmd.PersistentFlags().Bool("insecure-registry", cfg.InsecureRegistry, "skips verifying HTTPS certs, and allows falling back to plain HTTP")
 	// hosts-dir is defined as StringSlice, not StringArray, to allow specifying "--hosts-dir=/etc/containerd/certs.d,/etc/docker/certs.d"
 	rootCmd.PersistentFlags().StringSlice("hosts-dir", cfg.HostsDir, "A directory that contains <HOST:PORT>/hosts.toml (containerd style) or <HOST:PORT>/{ca.cert, cert.pem, key.pem} (docker style)")
-	// Experimental enable experimental feature, see in https://github.com/containerd/nerdctl/blob/master/docs/experimental.md
-	AddPersistentBoolFlag(rootCmd, "experimental", nil, nil, cfg.Experimental, "NERDCTL_EXPERIMENTAL", "Control experimental: https://github.com/containerd/nerdctl/blob/master/docs/experimental.md")
+	// Experimental enable experimental feature, see in https://github.com/containerd/nerdctl/blob/main/docs/experimental.md
+	AddPersistentBoolFlag(rootCmd, "experimental", nil, nil, cfg.Experimental, "NERDCTL_EXPERIMENTAL", "Control experimental: https://github.com/containerd/nerdctl/blob/main/docs/experimental.md")
 	return aliasToBeInherited, nil
 }
 
@@ -440,7 +440,7 @@ func AddStringFlag(cmd *cobra.Command, name string, aliases []string, value stri
 }
 
 // AddPersistentStringFlag is similar to AddStringFlag but persistent.
-// See https://github.com/spf13/cobra/blob/master/user_guide.md#persistent-flags to learn what is "persistent".
+// See https://github.com/spf13/cobra/blob/main/user_guide.md#persistent-flags to learn what is "persistent".
 func AddPersistentStringFlag(cmd *cobra.Command, name string, aliases, localAliases, persistentAliases []string, aliasToBeInherited *pflag.FlagSet, value string, env, usage string) {
 	if env != "" {
 		usage = fmt.Sprintf("%s [$%s]", usage, env)
@@ -491,7 +491,7 @@ func AddPersistentStringFlag(cmd *cobra.Command, name string, aliases, localAlia
 }
 
 // AddPersistentBoolFlag is similar to AddBoolFlag but persistent.
-// See https://github.com/spf13/cobra/blob/master/user_guide.md#persistent-flags to learn what is "persistent".
+// See https://github.com/spf13/cobra/blob/main/user_guide.md#persistent-flags to learn what is "persistent".
 func AddPersistentBoolFlag(cmd *cobra.Command, name string, aliases, nonPersistentAliases []string, value bool, env, usage string) {
 	if env != "" {
 		usage = fmt.Sprintf("%s [$%s]", usage, env)
@@ -528,7 +528,7 @@ func AddPersistentBoolFlag(cmd *cobra.Command, name string, aliases, nonPersiste
 }
 
 // AddPersistentStringArrayFlag is similar to cmd.Flags().StringArray but supports aliases and env var and persistent.
-// See https://github.com/spf13/cobra/blob/master/user_guide.md#persistent-flags to learn what is "persistent".
+// See https://github.com/spf13/cobra/blob/main/user_guide.md#persistent-flags to learn what is "persistent".
 func AddPersistentStringArrayFlag(cmd *cobra.Command, name string, aliases, nonPersistentAliases []string, value []string, env string, usage string) {
 	if env != "" {
 		usage = fmt.Sprintf("%s [$%s]", usage, env)
diff --git a/cmd/nerdctl/run.go b/cmd/nerdctl/run.go
index bf439655fde..3647f5a0326 100644
--- a/cmd/nerdctl/run.go
+++ b/cmd/nerdctl/run.go
@@ -72,7 +72,7 @@ func newRunCommand() *cobra.Command {
 		longHelp += "WARNING: `nerdctl run` is experimental on Windows and currently broken (https://github.com/containerd/nerdctl/issues/28)"
 	case "freebsd":
 		longHelp += "\n"
-		longHelp += "WARNING: `nerdctl run` is experimental on FreeBSD and currently requires `--net=none` (https://github.com/containerd/nerdctl/blob/master/docs/freebsd.md)"
+		longHelp += "WARNING: `nerdctl run` is experimental on FreeBSD and currently requires `--net=none` (https://github.com/containerd/nerdctl/blob/main/docs/freebsd.md)"
 	}
 	var runCommand = &cobra.Command{
 		Use:               "run [flags] IMAGE [COMMAND] [ARG...]",
diff --git a/docs/faq.md b/docs/faq.md
index 57d6fb33d74..5b4d44d3bba 100644
--- a/docs/faq.md
+++ b/docs/faq.md
@@ -48,7 +48,7 @@ Note that competing with Docker is _not_ the goal of nerdctl. Those cutting-edge
 
 ### How is nerdctl different from `ctr` and `crictl` ?
 
-[`ctr`](https://github.com/containerd/containerd/tree/master/cmd/ctr) is a debugging utility bundled with containerd.
+[`ctr`](https://github.com/containerd/containerd/tree/main/cmd/ctr) is a debugging utility bundled with containerd.
 
 ctr is incompatible with Docker CLI, and not friendly to users.
 
diff --git a/docs/rootless.md b/docs/rootless.md
index 141d460e367..4c9cfa5d4b1 100644
--- a/docs/rootless.md
+++ b/docs/rootless.md
@@ -102,7 +102,7 @@ $ export CONTAINERD_SNAPSHOTTER=stargz
 $ nerdctl run -it --rm ghcr.io/stargz-containers/alpine:3.10.2-esgz
 ```
 
-See https://github.com/containerd/stargz-snapshotter/blob/master/docs/pre-converted-images.md for the image list.
+See https://github.com/containerd/stargz-snapshotter/blob/main/docs/pre-converted-images.md for the image list.
 
 ## bypass4netns
 | :zap: Requirement | nerdctl >= 0.17 |
diff --git a/docs/stargz.md b/docs/stargz.md
index b3d4222d5ef..8bf3b2e278d 100644
--- a/docs/stargz.md
+++ b/docs/stargz.md
@@ -31,7 +31,7 @@ See https://github.com/containerd/stargz-snapshotter to learn further informatio
 # nerdctl --snapshotter=stargz run -it --rm ghcr.io/stargz-containers/fedora:30-esgz
 ```
 
-For the list of pre-converted Stargz images, see https://github.com/containerd/stargz-snapshotter/blob/master/docs/pre-converted-images.md
+For the list of pre-converted Stargz images, see https://github.com/containerd/stargz-snapshotter/blob/main/docs/pre-converted-images.md
 
 ### Benchmark result (Dec 9, 2020)
 For running `python3 -c print("hi")`, eStargz with Stargz Snapshotter is 3-4 times faster than the legacy OCI with overlayfs snapshotter.