API Tools - Development & Testing

JSON to GraphQL Schema Converter – Quick Type Defs

Paste a sample JSON response and get back a GraphQL type definition. Speeds up mocking an API layer from a REST endpoint.

API GraphQL JSON schema

Interactive GraphQL Query Builder – Point & Click

Paste a GraphQL schema or introspection result and build queries by checking fields. See the resulting query string and copy it for use in your app.

API builder GraphQL interactive query

Webhook Tester & Inspector - Online View Incoming Payloads

Generate a temporary webhook URL (mock) and view the JSON payloads sent to it. Great for testing integrations locally.

API inspector payload tester webhook

Broadcast Channel API Demo - Online Cross‑Tab Communication

Open the same page in two tabs and send messages between them. See real‑time cross‑tab communication. Learn the API.

API API Broadcast Channel messaging tabs

Platform Authenticator Demo - Online Fingerprint & Face ID

Test your device's built‑in biometric (Touch ID, Face ID, Windows Hello) using the Web Authentication API. Register and verify.

API demo Face ID fingerprint WebAuthn

Shared Worker Demo - Online Cross‑Tab State

Set up a Shared Worker that shares state across multiple browser tabs. Counter and messaging demo. Advanced web.

API demo Shared Worker state tabs

Private State Token Demo - Online Anti‑Fraud Test

Issue and redeem Private State Tokens (formerly Trust Tokens). Understand how they help detect bots without cookies.

API anti‑fraud API privacy trust token

WebAuthn Demo - Online Register & Authenticate

Create a passkey and authenticate using the Web Authentication API. Supports platform authenticators (TouchID, FaceID). No server.

API biometric passkey security WebAuthn

File Handle API Demo - Online Persistent File Access

Use the File System Access API with file handles for persistent read/write. Learn incremental saving patterns.

API API File Handle open save

Font Access API - Online Browse Local Fonts

Enumerate all fonts installed on your device and see a real‑time preview. Useful for design tools. Permission required.

API API Font Access fonts local

Intersection Observer Sandbox - Online Visual Threshold

Adjust root, margin, and threshold. See a live log of intersection events as you scroll. Debug lazy loading.

API debug Intersection Observer lazy threshold

Web Share Level 2 Tester - Online Share Files

Test sharing multiple files (images, PDFs) using the Web Share API. Check if the browser supports file sharing. Demo page.

API API files share Web Share

Cookie Store API Tester - Online Async Cookie Read/Write

Read, write, and delete cookies using the modern Cookie Store API. Monitor change events. No more document.cookie parsing.

API API async cookies Cookie Store

URLPattern API Tester - Online Route Matcher & Playground

Write a pattern and test it against URLs instantly. See which groups match. Learn the modern alternative to regex for routing. Works entirely in the browser.

API matcher playground routing URLPattern

Prioritized Task Scheduler Demo - Online scheduler.postTask()

Schedule tasks with user‑visible, user‑blocking, or background priority. See execution order and delays. Modern web perf.

API API postTask priority scheduler

Contact Picker API Demo - Online Select & Read Contacts

Pick a contact from the device’s address book (mobile). Read name, email, and phone. All permission‑based. Privacy safe.

API API Contact Picker contacts mobile

Web Notification Tester - Online Permission & Display

Check notification permission, request it, and send a test notification. Verify icon, body, and tag. Debug web push.

API API Notification permission test

cURL to Postman Collection - Online Simple Converter

Paste a cURL command and convert it into a minimal Postman collection JSON. Import and run. Local only.

API collection converter cURL Postman

API Request Builder - Online Test REST Endpoints

Select HTTP method, set headers, and body. Send requests and see the full response. Lightweight Postman alternative.

API API request REST test

Navigation API Playground - Online Single‑Page Router

Intercept and manage navigations without reloading. Test transition handling and URL updates. The future of client‑side routing.

API API Navigation router SPA

File System Access API Demo - Online Open & Save Files

Test the modern File System Access API. Open a file, modify it, and save back to disk. All sandboxed in browser.

API API File System Access open save

Web Bluetooth Scanner - Online Explore Nearby Devices

Scan for nearby Bluetooth Low Energy devices using the browser. Read device names and signal strength. Experimental API.

API BLE browser scanner Web Bluetooth

GraphQL Query Builder - Online Visual Construct Request

Build a GraphQL query by selecting fields and nesting visually. Copy the built query string. For learning and fast prototyping.

API builder GraphQL query visual

GraphQL Request Tester - Online Simple Client

Enter a GraphQL endpoint, write a query, and see the response. Add headers and variables. Simple testing client.

API client GraphQL request tester

FedCM Demo - Online Federated Credential Management

Experiment with the Federated Credential Management API. Simulate a sign‑in flow without third‑party cookies. Privacy‑first.

API API FedCM identity sign‑in

Idle Detection API Demo - Online User Activity Monitor

Request permission and detect when the user is idle (away from keyboard). See screen lock state. For native‑like apps.

API API Idle Detection monitor user

Compression Streams API Demo - Online Gzip/Deflate Raw

Compress and decompress text using the browser's native Compression Streams API. See the binary output size.

API API Compression Streams deflate gzip

Permissions Query API Demo - Online Check All APIs

Query the permission state of camera, microphone, geolocation, and more. See the response and learn the API.

API API demo Permissions query

HTTP Request Composer - Online Build & Send Requests

Pick a method, URL, headers, and body, then send an HTTP request directly from your browser. Debug APIs easily.

API API HTTP request test

Web Locks API Demo - Online Resource Coordination

Acquire and release locks across tabs. Prevent race conditions in IndexedDB or localStorage. Visual queue and lock state.

API API concurrency demo Web Locks

Web Share API Tester - Online Demo & Code

Test the Web Share API by sharing text, links, and files directly from the browser. Check compatibility and see example code.

API API share test Web Share

Swagger/OpenAPI YAML Previewer - Online Render & Test

Paste your Swagger/OpenAPI YAML and see a rendered API documentation preview with expandable endpoints. All local rendering.

API OpenAPI preview Swagger YAML

Web OTP API Demo - Online Auto‑Read SMS Codes

Demonstrate how the Web OTP API automatically reads one‑time codes from SMS (mobile). Simulation with a fake SMS input.

API API SMS verification Web OTP

Screen Orientation API Tester - Online Lock & Check

Check current screen orientation and test the lock API. Useful for mobile web apps. Demo with code.

API API mobile Screen Orientation test

Pointer Events Playground - Online Mouse, Touch & Pen

Unified input demo: see pressure, tilt, and type from any pointer. Compare pointerType values. Essential for drawing apps.

API API pen Pointer Events touch

GraphQL Playground - Online Query & Schema Explorer

Execute GraphQL queries against any endpoint with variables and headers. Explore schema via introspection. All requests made directly from your browser.

API API GraphQL query schema

Fullscreen API Tester - Online Request & Exit Demo

Test the Fullscreen API: request fullscreen on a colored div, detect changes, and copy the JavaScript boilerplate.

API demo Fullscreen API JavaScript test

Vibration API Demo - Online Test Haptic Feedback

Trigger different vibration patterns on mobile devices. Test if your phone supports haptic feedback. Simple demo.

API API haptic mobile Vibration

Clipboard API Tester - Online Read & Write Sandbox

Experiment with the Async Clipboard API: read/write text and images from the clipboard. Verify permissions and see demo code.

API API Clipboard copy paste