API Tester: REST & JSON Client

Test REST APIs anywhere, anytime. API Tester is a simple, lightweight HTTP client that lets you send requests to Web APIs and REST APIs from your Android phone or tablet and check the response in seconds.

Demo an API in a client meeting, check a production endpoint while you are out of the office, or look at a JSON response without opening your laptop. The method, URL and Send button stay at the top of the screen, so you can send a request from anywhere in the app.

▼ Who is this for?
・Developers who want to test APIs from a phone or tablet
・Engineers who need to check API behavior in meetings or while traveling
・Backend and REST API developers who want a quick way to hit an endpoint
・Anyone who wants to read JSON responses in a clean, formatted view
・Users who find desktop API tools too heavy for a quick check

▼ Main Features

【1】Build Requests
・HTTP methods: GET / POST / PUT / PATCH / DELETE / HEAD / OPTIONS
・Query parameter editor synced with the URL (edit either one)
・Request headers with a header type picker (multiple headers supported)
・Authentication: None / Basic / Bearer, with show/hide for passwords and tokens
・Request body in JSON or Text
・Format JSON button and syntax check that shows errors as you type
・Content-Type is added automatically to match the body (your own header wins)
・URL and header check before sending (e.g. full-width characters)

【2】Inspect Responses
・Status shown with color and icon (✓ 2xx, ⚠ 4xx, ✕ 5xx)
・Response time and size at a glance
・Response body in Pretty (formatted JSON) or Raw view
・Response headers
・Bodies and headers are shown for 404 / 500 errors, too
・Clear error messages by type (timeout, connection, SSL certificate, invalid URL) with a Retry button
・Cancel a request while it is in progress
・Works with http:// URLs such as local development servers

【3】History, cURL & Sharing
・Requests are saved to history automatically (up to 100)
・History cards with method colors and relative time ("5 minutes ago")
・Load a request from history with one tap
・Swipe to delete, with Undo
・Show and copy the request as a cURL command
・Copy or share responses and errors with other apps

【4】Settings
・Theme: System / Light / Dark
・Languages: English, Japanese, Chinese (Simplified), Spanish, German, Russian, Arabic, or follow the device language
・Privacy settings for ad consent

▼ Privacy
・History and settings are stored only on your device
・Basic credentials and Bearer tokens are never saved in history

▼ Use Cases
・Quick checks during REST API development
・Health checks on production and staging environments
・API demos in client meetings
・Checking APIs while traveling or commuting
・Showing junior engineers how HTTP requests and responses work

▼ A Note from the Developer
API Tester was built for one simple need: hit an API quickly and see the response, without complex setup. Install it and start testing REST APIs in seconds. The app is supported by a small banner ad at the bottom of the screen. We welcome your feedback and feature requests.

Recent changes:
A fresh new design.
- Method, URL and Send always at the top
- Status, time and size at a glance; 4xx/5xx bodies shown
- PATCH / HEAD / OPTIONS support
- Query parameters synced with the URL
- JSON formatting, syntax check, auto Content-Type
- Connect to http:// URLs (e.g. local servers)
- Cancel, timeouts and clearer error messages
- History cards with swipe to delete and undo; credentials no longer saved
- "System" theme and "Device language" options