HTTP Request Composer: Build & Test API Requests
Compose HTTP requests with custom methods, headers, and body, then send them and inspect the response. A lightweight in-browser client for quick API checks.
Runs in your browser. Nothing is uploaded.
How it works
- Step 1: Paste your inputPaste directly into the editor, drop a file onto it, or use "Open file" to pick one from your device. Nothing is sent anywhere when you do.
- Step 2: Run the toolAdjust the options if you need to, then run it. Results appear beside your input so you can compare the two.
- Step 3: Copy or download the resultCopy the result to your clipboard in one click, or save it as a file. You can also keep editing and re-run as many times as you like.
About this tool
- Runs in your browser. All processing happens locally in this tab using JavaScript.
- No uploads. Your data is never sent to a server. There is no server to send it to.
- Works offline. Once the page has loaded you can disconnect and keep working.
- Unlimited & free. No usage caps, no paywall, no file size tiers.
Start with your own data. Open a file
What happens to your data
The same questions a security review would ask, answered plainly.
- Read via
- Typed or pasted into the page
- Held in
- Your browser tab's memory for as long as it is open
- Stored
- Nothing. No cookies, no database, no server-side copy
- Transmitted
- The value you enter, to whatever URL you point it at, directly from your browser
- Retained after you close the tab
- Nothing
- Works offline
- No. This tool needs the network to answer
Why use this tool
What you get here that a server-side alternative cannot offer.
Your data never leaves the tab
There is no upload step and no server to receive one. The page loads once, then all work on your input happens in local JavaScript.
No caps or paywalls
No daily limits, no per-file ceilings imposed by a server tier, no watermarks, and no account. The practical limit is your own device's memory.
Frequently asked questions
Why does my request fail with a CORS error?
Browsers block cross-origin requests unless the target server sends permissive CORS headers. That is a server-side policy. A desktop client or curl is unaffected by it.
Are my requests proxied through a server?
No. Requests go directly from your browser to the target API, so credentials in headers are not seen by any intermediary of ours.
Which methods are supported?
GET, POST, PUT, PATCH, DELETE, and HEAD, each with custom headers and a request body where the method allows one.
Is my text uploaded to a server?
HTTP Request Composer is a static page with no backend of its own, and nothing you type is stored or logged here. It is one of the few tools on this site that does have to reach the network: answering the question at all means querying whatever URL you point it at, directly from your browser, so the value you enter is sent there. Every other tool in the catalogue is fully local.
How much data can I paste in?
There is no server-side cap. Very large inputs are limited only by your device's memory and will make the page feel slower, since the work happens on the main thread. In practice a few megabytes of text is comfortable.
Does it work offline?
No, and it is the exception. This tool has to query whatever URL you point it at, directly from your browser to answer, so it needs a connection even after the page has loaded. The rest of the catalogue keeps working with the network off.
Do I need to create an account?
No. There is no sign-up, no email, and no usage tracking tied to an identity. The tool works the first time you open it.