API Tester
Send REST requests from your browser and inspect the response: method, params, headers, body, auth, environment variables, history and saved requests.
- 9 Press 9 in the popup
- Runs in your browser
- Opens in its own window
An API tester that lives in your browser
API Tester is a lightweight REST client that opens in its own window from DevToolkit. Enter a URL, pick a method, add what the request needs and press Send. The response comes back with its status, time, size, headers and a nicely formatted body. There is no account to create, no workspace to sync and no heavy desktop app to install.
Build any request
- Methods: GET, POST, PUT, PATCH, DELETE, HEAD and OPTIONS.
- Params: add query parameters as rows instead of editing the URL by hand.
- Headers: set content types, API keys and any custom header.
- Body: send JSON, form data (URL-encoded) or plain text.
- Auth: Basic auth with a username and password, or a Bearer token.
Environment variables
Store values like a base URL, an API key or a user ID as variables and use them anywhere with {{name}}. Switch from a staging address to production by changing one variable instead of every request. If a request uses a variable you have not defined, API Tester tells you before sending.
History and saved requests
Your last 30 requests are kept in History, so you can send one again or tweak it in a click. Save the requests you use often under a name, and they are ready next time you open the window.
Read the response clearly
See the status code, how long the request took and how big the response was. JSON is pretty-printed for reading, headers have their own tab, and the body can be copied in one click. For deeper digging, paste a large response into JSON Formatter’s tree view.
Why test APIs in the browser?
Because you are already there. When a page’s request fails, you can copy the endpoint, try it with different headers or a different body, and see the result in seconds. Requests go straight from your browser to the API, with no proxy in the middle, and without the CORS errors a normal web page would run into.
Who uses it
- Front-end developers checking an endpoint before wiring it into the UI.
- Back-end developers testing new routes quickly.
- QA engineers reproducing bugs with exact requests.
- No-code builders testing webhooks and integrations.
Tip: Put your base URL in a variable like {{base}} so switching between staging and production is a one-field change.
How to test an API in Chrome
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Open API Tester
Click API Tester in DevToolkit (or press 9 on the hub). It opens in its own window.
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Build the request
Enter the URL, choose the method, and add params, headers, a body or auth.
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Send and inspect
Press Send and read the status, time, headers and body. Save it for next time.
What you can do with API Tester
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All common methods
GET, POST, PUT, PATCH, DELETE, HEAD and OPTIONS.
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Params, headers, body
JSON, form data or text bodies, edited as rows.
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Basic and Bearer auth
Add credentials without writing headers by hand.
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Environment variables
Reuse values with {{name}} across every request.
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History and saved requests
Your last 30 requests, plus named favourites.
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Clear responses
Status, time, size, headers and pretty JSON.
API Tester questions
Is API Tester free?
API Tester is part of DevToolkit Pro, a one-time payment from $25 with no subscription.
Is it a Postman alternative?
For everyday request testing, yes. It covers methods, params, headers, bodies, auth, variables, history and saved requests. It does not try to replace team workspaces, test scripts or mock servers.
Will I get CORS errors?
No. Requests are sent by the extension rather than by a web page, so browser CORS rules that block page scripts do not apply.
Are my requests and keys stored online?
No. History, saved requests and variables are kept in your browser on your computer. Requests go straight to the API you call.
Can I test an API running on localhost?
Yes. Enter the local address, such as http://localhost:3000/api, and send the request like any other. Remember to write http:// for local servers that do not use HTTPS.
Try API Tester today
Install DevToolkit free, then unlock every Pro tool with one payment. No subscription.