Online API Testing Tool

Introduction:

Hyper-Text Transfer Protocol (HTTP) application-programming interfaces let two systems exchange structured data over the web. Each call follows a request–response pattern containing a method, target URL, optional headers, and a body that encodes payload details.

This online tool lets you compose every element of an HTTP call—method, endpoint, query string, headers, authentication, and body—inside a reactive engine. The component then sends the call directly from your browser, captures the raw response, and formats headers and body for review.

You might confirm a new endpoint before writing code, inspect unexpected status codes received in production, or share a reproducible request with a colleague. *Remember that calling secured endpoints from public networks may expose credentials.*

Technical Details:

Concept Overview

HTTP defines a stateless, text-based protocol where a client opens a TCP connection, sends a request line containing the verb and path, adds optional header fields, and transmits an optional message body. The server replies with a three-digit status code, response headers, and an optional body that may be JSON, XML, HTML, or binary.

Core Request-Response Structure

1. Select method (GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS).
2. Build the absolute URL and attach any query parameters.
3. Add headers—content type, accepted formats, custom keys.
4. Optionally encode a message body; most APIs expect JSON.
5. Apply authentication credentials (Basic or Bearer) if required.
6. Send the request and await the response status line, headers, and body.

Status-Code Interpretation

Variables & Parameters

• method – HTTP verb controlling the operation performed.
• url – absolute or schemeless target endpoint.
• query – key–value pairs appended to the URL.
• headers – additional metadata such as Content-Type.
• body – request payload for non-idempotent verbs.
• authType – None, Basic, or Bearer token.

Worked Example

GET https://api.example.com/users?page=2 HTTP/1.1
Accept: application/json
Authorization: Bearer your_token
    

Assumptions & Limitations

• Client-side only – no cross-domain proxy; CORS must be enabled on the target API.
• Large binary bodies display as plain text; they are not decoded.
• Streaming responses are read fully before display, which may delay huge downloads.
• Only Basic and Bearer auth are supported; other schemes require manual header entry.

Edge Cases & Error Sources

• HTTP 301/302 responses follow redirects automatically; disabled by some servers.
• Self-signed TLS certificates trigger network errors in modern browsers.
• Malformed JSON bodies return raw text because parsing fails.
• Headers with duplicate names are combined by the browser’s fetch implementation.

Scientific Validity & References

Based on RFC 7230–7235 (HTTP/1.1), RFC 9110 (Semantics), and WHATWG Fetch Living Standard.

Privacy & Compliance

The application processes request data entirely in the browser; no payloads are transmitted to third-party servers, aiding GDPR compliance.

Step-by-Step Guide:

The sequence below walks you through crafting and sending a request.

1. Choose a Method matching the operation.
2. Enter the full URL or paste a complete cURL command.
3. Open Params to add or toggle query keys.
4. Populate Headers for content type, tokens, or custom keys.
5. Switch to Body and paste JSON or form data when required.
6. Select Auth, choose Basic or Bearer, and enter credentials.
7. Review the generated Raw request, then press Send.
8. Inspect Status, Headers, and formatted Body in the Response pane.

FAQ:

Glossary:

HTTP Method

Verb indicating the desired action on the resource.

Header

Key–value pair conveying metadata for the request or response.

Status Code

Three-digit server response classification.

Body

Optional payload sent with non-idempotent requests or returned by the server.

Authentication

Mechanism verifying client identity, such as Basic or Bearer token.