API Tester Pro is a powerful browser extension for testing REST, GraphQL, and WebSocket APIs in one place. It allows developers to send requests, analyze responses, and manage configurations easily. With a clean interface and local storage, it streamlines API workflows without relying on external tools or services.
Editor score is the AltFTool team’s own rating, not user reviews.
Features
Test REST APIs with full request customization
Manage headers and request data
Screenshots
Select a screenshot to view it larger.
Install
Step 1: Open the extension's page on AltFTool and choose “Add to Chrome”. The official Chrome Web Store listing opens in a new tab.
Step 2: On the store listing, check the developer, the description and the permissions the extension asks for.
Step 3: Click “Add to Chrome”, read the permission prompt Chrome shows, then confirm with “Add extension”.
Step 4: Pin it. Open the puzzle-piece Extensions menu next to the address bar and click the pin icon so it stays one click away.
Permissions & privacy
Chrome shows the exact permissions API Tester Pro asks for before you confirm the install. You can also read them, and the developer’s data declarations, in the Privacy practices section of the store listing.
Explain permissions with the free analyzerFAQ
Yes. API Tester Pro is a free Chrome extension from AltFTool and does not need an AltFTool account.
Choose “Add to Chrome” on this page to open the official Chrome Web Store listing, review the permissions, then click “Add extension” and pin it from the Extensions menu.
API Tester Pro is built for Google Chrome. Chromium-based browsers such as Microsoft Edge, Brave and Opera can usually install Chrome Web Store extensions too; Firefox and Safari cannot.
Test REST APIs with full request customization; Manage headers and request data.
Chrome shows the exact permissions before you confirm the install, and the store listing shows them too. Paste them into AltFTool's Browser Extension Permission Analyzer for a plain-English explanation.
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Free, no AltFTool account needed. Installs from the official Chrome Web Store.