Online API Tester

DataFormatter API Tester is a free online tool to build and send GET, POST, PUT and DELETE requests with headers, auth and JSON bodies directly from your browser — no proxy, no signup and no logging.

About this tool

What is it?: DataFormatter API Tester is a free online tool to build and send GET, POST, PUT and DELETE requests with headers, auth and JSON bodies directly from your browser.
Who is it for?: Developers debugging endpoints and inspecting responses without leaving the tab or using a separate desktop app.
What makes DataFormatter's tool different?: It sends requests straight to the endpoint with no proxy and no signup — cross-origin responses depend only on the endpoint's CORS policy, and nothing is logged.

What the API Tester does

Build and send GET, POST, PUT and DELETE requests with headers, authentication and JSON bodies.
Replay and iterate on requests while inspecting the raw response status, headers and body.
Send directly to the endpoint — requests are not routed through any server-side proxy.
Work with local, staging or public servers and see results immediately in the browser.

API Tester vs API Client

The API Tester shares its engine with the API Client — the same direct-from-browser, no-proxy request workflow for GET, POST, PUT and DELETE. Use this page for quick checks, or open the API Client for the same workflow alongside the full built-in documentation of every feature.

When to use the API Tester

Checking a new endpoint

Send a request to a just-added route and confirm the status code and response body.

Debugging auth flows

Try different bearer tokens or headers and see exactly how the server responds.

Frontend API work

Verify the requests your frontend will make, including headers and payload shape.

Built-in privacy by design

Requests are sent straight from your browser. Cross-origin endpoints only respond when they allow it via CORS — there is no server-side proxy, so nothing is ever forwarded or logged and your data stays on your machine.

Frequently asked questions

Is DataFormatter's API Tester free and does it require signup?

Yes, it is completely free with no account or signup. You can build and send GET, POST, PUT and DELETE requests straight from your browser.

Does the API Tester use a proxy or log my requests?

No. Requests are sent directly to the target endpoint from your browser — there is no server-side proxy, so nothing is forwarded, logged or uploaded.

Why does a request sometimes fail?

Because calls go straight to the endpoint, cross-origin endpoints only respond when they allow it via CORS. This is by design — it means no intermediate service ever touches your request.

What can I send with the API Tester?

You can build GET, POST, PUT and DELETE requests with custom headers, authentication and JSON bodies, replay them, and inspect the raw response.

Related tools

Last reviewed September 2026 · DataFormatter team — this tool processes data locally in your browser.