HTML APIs

Full list available here https://developer.mozilla.org/en-US/docs/Web/API 

Location & Device APIs

• Geolocation API – Get user’s location.
• Device Orientation API – Access accelerometer and gyroscope data.
• Device Motion API – Detect physical movement of the device.
• Battery Status API – Get battery charge and status info (deprecated in most browsers for privacy).

Media & Hardware Access APIs

• MediaDevices API – Access camera, microphone, screen (e.g., getUserMedia()).
• WebRTC API – Real-time audio, video, and data communication.
• Screen Capture API – Capture screen/window for recording or sharing.

File & Storage APIs

• File API – Read and manipulate files from file inputs or drag-and-drop.
• File System Access API – Read and write to the user’s local file system.
• Web Storage API – localStorage and sessionStorage.
• IndexedDB API – NoSQL-style database for storing large amounts of structured data.
• Cache API – Store and retrieve network requests and responses.
• Cookies

Networking & Communication APIs

• Fetch API – Modern way to make HTTP requests.
• WebSocket API – Bi-directional communication with a server.
• Server-Sent Events (EventSource) – Push updates from server to client.
• Beacon API – Send analytics/data to server asynchronously when page is unloading.

Web Workers & Threads

• Web Workers API – Run scripts in background threads.
• Service Workers API – Control caching, offline access, and background sync.

User Interaction APIs

• Drag and Drop API – Built-in drag-and-drop support.
• Clipboard API – Read from and write to the system clipboard.
• Fullscreen API – Display elements in full screen.
• Vibration API – Make the device vibrate (mostly for mobile, limited support).
• Gamepad API – Access game controller input.

AI & Sensor APIs

• Speech Recognition API – Convert spoken input to text.
• Speech Synthesis API – Convert text to spoken voice.
• WebXR / WebAR / WebVR APIs – Support for virtual and augmented reality experiences.
• Ambient Light Sensor API – Detect ambient light level (limited support).

Graphics & Animation APIs

• Canvas API – Draw 2D graphics.
• WebGL / WebGL2 – Render 3D graphics.
• Web Animations API – Control animations using JavaScript.
• SVG API – Scalable vector graphics manipulation.

Other Useful APIs

• Notifications API – Show system notifications.
• Permissions API – Check and request permissions for APIs (e.g., geolocation).
• Intersection Observer API – Efficiently watch element visibility (e.g., lazy-loading).
• Mutation Observer API – Watch for DOM changes.
• Resize Observer API – Watch for size changes of elements.
• Credential Management API – Manage user credentials (passwords, federated login).
• Payment Request API – Integrate with native payment systems.
• Web Share API – Share content via native share dialog (mobile-first).