UpturaBeta
Free API tool

Free Online API Tester

Test any API endpoint online — like running curl in your browser. Send a request, add your own headers, and inspect the status code, response time, headers, and body. Then monitor it 24/7, free.

Free · no sign-up · sends one live GET request from our servers.

What you get

Everything you need to test an API endpoint

One request gives you the full picture — status, latency, headers, body, and pass/fail assertions — no Postman, no install, no account.

  • Status code & response

    Send a live GET or HEAD request to any endpoint and see the exact HTTP status code and status text it returns — 200, 404, 500, or anything else — in a second.

  • Response time

    Every request is timed end to end, so you can see how fast (or slow) your API responds and catch latency problems before your users feel them.

  • Response headers

    Inspect the full set of response headers — content-type, server, cache-control, CORS, and more — exactly as the endpoint sends them back.

  • Response body & JSON

    See the raw response body, pretty-printed automatically when it's JSON, so you can confirm the payload is shaped the way your app expects.

  • Custom request headers

    Add your own headers — an Authorization token, an API key, a custom Accept — to test endpoints behind auth, not just open ones. Nothing is stored.

  • Assertions

    Assert the expected status code, a response-time limit, and a keyword or JSON-path check on the body — so a 200 that returns the wrong data is flagged as a fail, not a pass.

Why it matters

A quick test can save a broken release

APIs fail quietly — a wrong status, a slow response, a missing field. Here's why a fast check pays off.

  • A 200 can still be broken

    An endpoint can return a healthy 200 while the payload is empty, malformed, or missing a field your app depends on. Assertions catch the responses a plain status check would wave through.

  • No Postman, no install

    Paste a URL and send a request straight from the browser — like running curl online. No app to download, no account, no collection to set up just to check one endpoint.

  • Catch slow APIs early

    Response time creeping up is the first sign of trouble. Test an endpoint's latency now, then let Uptura watch it around the clock and alert you before it turns into timeouts.

From tester to monitor

Turn a one-off test into continuous API monitoring

The tester checks your endpoint right now. Uptura's free API monitoring runs the same request on a schedule and alerts you the instant it starts failing.

  1. 1

    Test your endpoint

    Run a one-off request here to confirm the status, latency, and response body are what you expect.

  2. 2

    Add it to Uptura

    Create a free account and add the endpoint — with the same headers and assertions — to your dashboard in a minute.

  3. 3

    Get alerted on failures

    Uptura calls it on a schedule and messages you the moment it returns the wrong status, slows down, or fails an assertion.

Start monitoring free

Free during our public beta, no credit card required. Prefer to read more first? See how API monitoring works.

The guide

API testing, without the jargon

What it is, the types that matter, and a strategy that survives a real deadline — plus where a quick browser test fits in.

What API testing really checks

Every app you use is a stack of APIs quietly talking to each other. API testing is how you find out whether those conversations are actually going the way you assume — before a customer does. The useful question isn't "did the endpoint respond?" It's "did it respond correctly, quickly, and safely, every single time?"

That distinction matters more than it sounds. A login route that returns a healthy 200 but hands back an empty token is technically working and completely broken. Good testing is what tells those two apart — and it's why checking the response body beats trusting the status code alone.

The main types of API testing

Most teams don't run every kind of test formally, and that's fine. But it helps to know which one you're leaning on and which one you're skipping:

  • Functional testing — the baseline — send a request and confirm the response matches the contract: right status, right shape, right values. This is where most REST API testing starts.
  • Integration testing — steps back to check endpoints work together — that the user your "create" call returns actually shows up in the "get" call a moment later.
  • API performance testing — asks the harder question: is it still fast when a thousand people hit it at once? An endpoint that's snappy in dev and times out at peak is a classic.
  • API security testing — probes what attackers probe — can you read another user's data by changing an ID in the URL, does the endpoint leak stack traces, does auth actually hold under pressure.
  • Contract testing — pins down the agreement between an API and the apps that consume it, so a "harmless" field rename doesn't silently break three front-ends at once.

A simple API testing strategy that holds up

The best of the API testing strategies isn't the most thorough one on paper — it's the one you'll actually keep doing when there's a deadline breathing down your neck. A few principles that survive contact with reality:

  • Test the response, not just the status — a 200 with an empty array is still a bug. Assert on the body's shape and a value or two you care about.
  • Cover the unhappy paths — bad input, missing auth, an expired token. That's where the real bugs live — the happy path was always going to work.
  • Assert on time, not only correctness — set a latency ceiling and treat crossing it as a failure. Slow is a bug your users feel before you do.
  • Keep the fast checks close — if verifying an endpoint takes ten minutes of setup, you'll skip it exactly when you're rushing — which is exactly when things break.

Manual vs automated API testing

There's a place for both, and pretending otherwise wastes everyone's time. Poking at an endpoint by hand is perfect when you're debugging something specific or exploring an API you've never touched — it's fast, tactile, and you learn the shape of things as you go.

Automated API testing earns its keep for the checks you run over and over: the smoke test after every deploy, the nightly run against staging, the one endpoint that's failed before and you quietly no longer trust. The honest rule of thumb — if you've tested the same thing by hand three times, it's time to automate it. Plenty of API testing tools can do this, from full frameworks down to lightweight scheduled checks, and the right one is simply the one your team will actually keep running.

Where a quick online tester fits

Not every check needs a framework. Sometimes you just want to know, right now, whether an endpoint is up and returning the right thing — after a deploy, during an incident, or when a teammate swears it works on their machine. That's what the tester at the top of this page is for: paste the URL, add your headers, send, and read the status, timing, headers, and body in about a second. No install, no account.

The moment a one-off check turns into "I need to know the instant this breaks," you've crossed the line from testing into monitoring. That's where Uptura picks up — it runs the same request on a schedule, checks the same assertions, and messages you the second something's off, so you're never the one refreshing an endpoint at 2am hoping it holds.

FAQ

Testing APIs online, answered

  • What is an online API tester?

    An online API tester lets you send an HTTP request to an API endpoint from your browser and inspect the response — the status code, response time, headers, and body — without installing anything. Uptura's is free and needs no sign-up: paste a URL, pick GET or HEAD, add any headers, and send.

  • How do I test an API endpoint?

    Enter the endpoint's full URL (for example https://api.example.com/v1/health), choose the HTTP method, optionally add request headers like an Authorization token, and send. The tester shows the HTTP status, how long the request took, the response headers, and the response body — with pass/fail assertions on the status code, latency, and body content.

  • Is this like running curl online?

    Yes — it's essentially curl in your browser. Instead of typing a curl command in a terminal, you paste the URL, add any headers, and send the request from our servers. You get back the same information curl -i would show you: the status line, the response headers, and the body.

  • Can I test an API that requires authentication?

    Yes. Add an Authorization header (such as a Bearer token) or an API key header, and the tester sends it with the request so you can check endpoints behind auth. Nothing you enter is stored — the request is one-off and headers are never saved.

  • What HTTP methods are supported?

    The free tester sends GET and HEAD requests — the safe, read-only methods that can't modify data. Write methods (POST, PUT, PATCH, DELETE) with request bodies are on the roadmap. For now it's built for safely checking that an endpoint is up and returning the right response.

  • What are assertions and why use them?

    Assertions define what a healthy response actually looks like. You can require a specific status code, a maximum response time, and a keyword or JSON-path check on the body. That way an endpoint returning 200 with the wrong or empty payload is correctly flagged as a failure instead of passing.

  • Is the API tester free? Do I need an account?

    It's completely free and needs no sign-up — test as many endpoints as you like. If you want Uptura to keep calling an endpoint on a schedule and alert you when it fails, you can create a free account for continuous API monitoring.

  • How is this different from API monitoring?

    This tool sends a single request when you click the button. Uptura's API monitoring runs the same request on a schedule — as often as every few minutes — asserts the status, latency, and body, and alerts your team the instant an endpoint breaks, so you catch failures before your users do.

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Stop finding out about API failures from your users

Add your endpoints and let Uptura call them around the clock — with the same assertions — and alert you the moment one breaks. Free during our public beta.

Start freeLog in

Free during beta · no credit card required