An online API tester that works like curl. Pick a method, add headers and a body, and see the status code, the response body and where the time went, from six AWS regions at once.
This is the curl command you would have typed, as a form. Choose GET, POST, PUT, PATCH, DELETE, HEAD or OPTIONS, add the headers the API expects, paste a JSON or raw body for the methods that take one, and send it. LoadFocus makes the request from its own servers and shows you exactly what came back: the status code, every response header, the body, the SSL certificate, and a breakdown of where the time went. Nothing to install and nothing to sign up for.
A terminal shows one result from one place. A GET, HEAD or OPTIONS request here is sent from six AWS regions at the same time, so you can see whether the API answers differently in Tokyo than in Virginia, which is what your users in Tokyo actually experience. Requests that change data, so POST, PUT, PATCH and DELETE, are sent exactly once, from one region, because a request that creates or deletes something must not be repeated six times on your behalf.
The request goes to the address you enter, with the method and headers you set, and the endpoint treats it as real. That is the point of the tool and also why it is careful: a request that changes data is never retried, and if it times out the result says the outcome is unknown rather than pretending it failed, because the server may well have processed it. Redirects are reported rather than followed. Header names are validated, hop-by-hop headers are dropped, and your Authorization header is sent to the API you named and never written to any log.
A request you send by hand tells you the API works now. The same request, sent every minute from 25+ regions with assertions on the status code and the body, tells you the moment it stops working, before a customer does. That is the LoadFocus API monitor, and its free plan starts with exactly the request you just sent.
Related: API Monitoring · API Status Checker · curl to k6 · curl to JMeter · Free API load test
One request returns more than a status code. These are the values worth reading:
How the server answered. 2xx is success, 3xx a redirect (reported, not followed), 4xx means the request was refused, missing or needs authentication, 5xx means the server failed. A 401 or 403 with the right headers set usually means the header value is wrong, not the tool.
What the API sent back, shown as text and pretty-printed when it is JSON. Large bodies are cut at 64 KB with a note saying so, and binary responses such as images are reported by size rather than displayed. The body is shown as text only, never rendered, so a page that returns HTML cannot run anything here.
Content type, caching, CORS, rate-limit counters and the server's own identification. When an API misbehaves the answer is often in a header: a wrong Content-Type, a missing Access-Control-Allow-Origin, or an X-RateLimit-Remaining of zero.
How long the server took to start answering after the connection was ready. Under 800 ms is good for an API. A slow TTFB with fast DNS and TLS means the work is on the server side: a slow query, a cold cache or an overloaded backend.
The cost of reaching the server before the request is even sent. High DNS time points at the resolver or a slow authoritative server; high TLS time points at the certificate chain or a handshake that is renegotiated on every call instead of being reused.
For safe methods the same request is timed from six regions. The gap between the fastest and slowest is what a global audience actually sees, and a status code that differs between regions usually means a deployment or a CDN edge that did not finish rolling out.