What Is API Request Builder?

API Request Builder constructs HTTP requests visually — set the method (GET, POST, PUT, DELETE, PATCH), URL, headers, query parameters, and request body, then generate the equivalent code in cURL, JavaScript fetch, Python requests, and other languages. It’s a faster alternative to writing API calls from scratch.

How to Use This Tool

Select an HTTP method, enter the endpoint URL, and add headers, query parameters, and body content using the form fields. The tool generates the equivalent request code in multiple languages in real time. Copy the code snippet for your language of choice. Everything runs in your browser — no requests are actually sent from this tool.

Why Use API Request Builder?

Building API requests with correct headers, authentication, and body formatting is error-prone, especially when switching between languages. This tool gives you a visual editor with instant code generation across multiple languages, saving time and reducing syntax mistakes. It’s free, private, and requires no account. For a detailed walkthrough, see our step-by-step guide.

Common Use Cases

Drafting a curl command before you wire it into a deploy script, so you can test the exact request shape without leaving the browser. Reproducing a failing request from a production log: paste in the URL, headers, and body and you have a self-contained snippet you can hand to a teammate or attach to a bug report. Generating starter code for a new client library so every example block in your documentation renders the same call in fetch, axios, curl, and Python requests form.

Onboarding a new API where the docs are vague about authentication headers, the expected content type, or whether tokens go in the query string or the Authorization header. Building the request in the UI surfaces those decisions explicitly. Also useful as a teaching aid: students can see one request rendered in multiple languages, which makes the underlying HTTP shape the focus rather than any single language's idioms.

How We Compare

Postman and Insomnia are full request-management apps with collections, workspaces, and team sync — overkill if you just need to shape one request and hand it off. The browser-extension request builders are lighter but still require an install and a permissions prompt that some workplaces block by policy. SaaS request builders work but route your headers and body through their servers, which is uncomfortable when those carry production credentials.

This tool sits at the other end of the spectrum: open a tab, fill in the fields, copy the snippet, close the tab. Nothing persists between sessions, nothing leaves the device, and there's no install. For converting an existing curl command into language-specific code instead, see curl-to-code, which works in the inverse direction and shares the same code-generation backend.

Frequently Asked Questions

What HTTP methods are available?+
GET, POST, PUT, PATCH, DELETE. GET retrieves, POST creates, PUT replaces, PATCH updates, DELETE removes.
What code formats?+
cURL for terminal, fetch API, and axios. Each includes method, URL, headers, and body.
Does this send real requests?+
No. It only generates code snippets. Copy and run in your own environment.
What are query parameters?+
Key-value pairs after ? in the URL for filtering, pagination, and search.
Can I save and replay requests?+
Yes — saved requests persist in browser localStorage, organised into collections. Export collections as JSON for sharing or version control. No account required.
Does the tool support authentication?+
Yes — Basic, Bearer Token, API Key (header or query), and OAuth 2.0 (Authorization Code flow with PKCE) are all supported. Credentials stay in your browser — nothing is sent to a UDT server.
Can I run requests against localhost?+
Yes for HTTP — your browser permits same-origin and CORS-enabled cross-origin requests. For local APIs without CORS headers, browser security blocks the request — use a local dev proxy or enable CORS on your dev server.
How does this compare to Postman or Insomnia?+
Postman/Insomnia are desktop apps with more advanced features (environments, scripts, mock servers). This tool covers the 80% case for quick API testing without an install — paste a URL, set headers, send. Collections export to Postman format for migration.

Built by Derek Giordano · Part of Ultimate Design Tools

Privacy Policy · Terms of Service