diff --git a/.gitignore b/.gitignore
index e417f7a..ad224e7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ node_modules
 .env
 coverage
 *.log
+package-lock.json
diff --git a/README.md b/README.md
index 5fd76de..9c1acfd 100644
--- a/README.md
+++ b/README.md
@@ -102,7 +102,7 @@ const {bluetooth, destroy} = createBluetooth()
 ## `Bluetooth`
 | Method | Description |
 | --- | --- |
-| `String[] adapters()` | List of available adapters |
+| `Promise<String[]> adapters()` | List of available adapters |
 | `Promise<Adapter> defaultAdapter()` | Get an available adapter |
 | `Promise<Adapter> getAdapter(String adapter)` | Get a specific adapter (one of available in `adapters()`)|
 
@@ -148,7 +148,7 @@ const {bluetooth, destroy} = createBluetooth()
 | Method | Description |
 | --- | --- |
 | `Promise<String[]> services()` | List of available services |
-| `Promise<GattService[]> getPrimaryService(String uuid)` | Returns a specific Primary Service |
+| `Promise<GattService> getPrimaryService(String uuid)` | Returns a specific Primary Service |
 
 ## `GattService`
 | Method | Description |
@@ -166,7 +166,7 @@ const {bluetooth, destroy} = createBluetooth()
 | `Promise<String[]> getFlags()` | Defines how the characteristic value can be used. |
 | `Promise<bool> isNotifying()` | True, if notifications or indications on this characteristic are currently enabled. |
 | `Promise<Buffer> readValue(Number offset = 0)` | Issues a request to read the value of the characteristic and returns the value if the operation was successful. |
-| `Promise<Buffer> writeValue(Buffer buffer, Number offset = 0)` | Issues a request to write the value of the characteristic. |
+| `Promise<void> writeValue(Buffer buffer, Number offset = 0)` | Issues a request to write the value of the characteristic. |
 | `Promise<void> startNotifications()` | Starts a notification session from this characteristic if it supports value notifications or indications. |
 | `Promise<void> stopNotifications()` | This method will cancel any previous StartNotify transaction. |
 | `Promise<String> toString()` | User friendly characteristic name. |
diff --git a/package.json b/package.json
index 8a81c17..c657307 100644
--- a/package.json
+++ b/package.json
@@ -6,6 +6,7 @@
   "author": "chrvadala",
   "license": "MIT",
   "main": "./src/index.js",
+  "typings": "./src/index.d.ts",
   "files": [
     "*.md",
     "src",
@@ -28,7 +29,8 @@
     "coverage": "jest --testPathIgnorePatterns=e2e.spec.js --coverage",
     "test:e2e": "jest",
     "standard": "standard",
-    "ci": "npm-run-all standard coverage",
+    "ci": "npm-run-all standard coverage typescript",
+    "typescript": "tsc --strict src/index.d.ts",
     "build": "exit 0"
   },
   "dependencies": {
@@ -38,10 +40,12 @@
     "@babel/plugin-proposal-class-properties": "^7.10.1",
     "@babel/plugin-proposal-decorators": "^7.10.1",
     "@types/jest": "^25.2.3",
+    "@types/node": "^14.0.13",
     "dotenv": "^8.2.0",
     "jest": "^26.0.1",
     "npm-run-all": "^4.1.5",
-    "standard": "^14.3.4"
+    "standard": "^14.3.4",
+    "typescript": "^3.9.5"
   },
   "standard": {
     "ignore": [
diff --git a/src/index.d.ts b/src/index.d.ts
new file mode 100644
index 0000000..7df0863
--- /dev/null
+++ b/src/index.d.ts
@@ -0,0 +1,81 @@
+import events = require('events');
+
+declare namespace NodeBle {
+    interface GattCharacteristic extends events.EventEmitter {
+        getUUID(): Promise<string>;
+        getFlags(): Promise<string[]>;
+        isNotifying(): Promise<boolean>;
+        readValue(offset?: number): Promise<Buffer>;
+        writeValue(buffer: Buffer, offset?: number): Promise<void>;
+        startNotifications(): Promise<void>;
+        stopNotifications(): Promise<void>;
+        toString(): Promise<string>;
+
+        on(event: 'valuechanged', listener: (buffer: Buffer) => void): this;
+    }
+
+    interface GattService {
+        isPrimary(): Promise<Boolean>;
+        getUUID(): Promise<string>;
+        characteristics(): Promise<string[]>;
+        toString(): Promise<string>;
+        getCharacteristic(uuid: string): Promise<GattCharacteristic>;
+    }
+
+    interface GattServer {
+        services(): Promise<string[]>;
+        getPrimaryService(uuid: string): Promise<GattService>;
+    }
+
+    interface ConnectionState {
+        connected: boolean;
+    }
+
+    interface Device extends events.EventEmitter {
+        getName(): Promise<string>;
+        getAddress(): Promise<string>;
+        getAddressType(): Promise<string>;
+        getAlias(): Promise<string>;
+        getRSSI(): Promise<string>;
+        isPaired(): Promise<string>;
+        isConnected(): Promise<string>;
+        pair(): Promise<void>;
+        cancelPair(): Promise<void>;
+        connect(): Promise<void>;
+        disconnect(): Promise<void>;
+        gatt(): Promise<GattServer>;
+        toString(): Promise<string>;
+
+        on(event: 'connect', listener: (state: ConnectionState) => void): this;
+        on(event: 'disconnect', listener: (state: ConnectionState) => void): this;
+    }
+
+    interface Adapter {
+        getAddress(): Promise<string>;
+        getAddressType(): Promise<string>;
+        getName(): Promise<string>;
+        getAlias(): Promise<string>;
+        isPowered(): Promise<boolean>;
+        isDiscovering(): Promise<boolean>;
+        startDiscovery(): Promise<void>;
+        stopDiscovery(): Promise<void>;
+        devices(): Promise<string[]>;
+        getDevice(uuid: string): Promise<Device>;
+        waitDevice(uuid: string): Promise<Device>;
+        toString(): Promise<string>;
+    }
+
+    interface Bluetooth {
+        adapters(): Promise<string[]>;
+        defaultAdapter(): Promise<Adapter>;
+        getAdapter(adapter: string): Promise<Adapter>;
+    } 
+
+    function createBluetooth(): {
+        destroy(): void;
+        bluetooth: Bluetooth;
+    };
+}
+
+export = NodeBle;
+