API & Network Helpers

API & Network Helpers – Free Online HTTP Tools | SWE Helper
← Back to All Tools

🌐 API & Network Helpers

Build HTTP requests, convert cURL commands, validate JSON schemas, and more — all in your browser.

HTTP Request Builder

Build a fetch() request visually and generate JavaScript code + cURL command.

Usage Guide

How to use

  • Select an HTTP method and enter the target URL.
  • Add headers as key-value pairs (click + Add Header).
  • For POST/PUT/PATCH, add a JSON body.
  • Click Generate Code to get the fetch() snippet and cURL command.
  • Click ▶ Send Request to actually execute the request from your browser.

Notes

  • Sending requests is subject to CORS restrictions. The target server must allow cross-origin requests.
  • Generated code can be copied and used directly in Node.js or browser projects.

Example

GET https://jsonplaceholder.typicode.com/posts/1
Header: Accept: application/json

cURL → Fetch/JS Converter

Paste a cURL command and convert it to JavaScript fetch() code.

Usage Guide

Supported cURL flags

  • -X / --request — HTTP method
  • -H / --header — Headers
  • -d / --data / --data-raw — Request body
  • -u / --user — Basic authentication (user:pass)
  • URL (with or without quotes)

Example

curl -X POST https://api.example.com/users \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer token123" \
  -d '{"name":"Alice","email":"alice@test.com"}'

HTTP Status Code Reference

Search and browse all HTTP status codes with descriptions and common use cases.

Usage Guide

How to use

  • Type a status code number or keyword in the search box to filter.
  • Click a category button to filter by class (1xx, 2xx, etc.).
  • Hover over a card for full details.

Common groupings

  • 1xx — Informational: request received, continuing.
  • 2xx — Success: request was received, understood, accepted.
  • 3xx — Redirection: further action needed to complete the request.
  • 4xx — Client Error: request contains bad syntax or cannot be fulfilled.
  • 5xx — Server Error: server failed to fulfill a valid request.

HTTP Header Parser

Paste raw HTTP headers and parse them into a structured table with descriptions.

Usage Guide

How to use

  • Copy headers from browser DevTools (Network tab → click a request → Headers).
  • Paste them into the text box — one header per line, in Name: Value format.
  • Click Parse Headers to see a table with descriptions.

Supported formats

  • Header-Name: value
  • Lines starting with HTTP/ (status lines) are included.
  • Empty lines and comment lines are skipped.

Example

HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Cache-Control: max-age=3600
X-Powered-By: Express

JSON Schema Validator

Validate a JSON document against a JSON Schema. Supports type, required, properties, min/max, enum, pattern.

Usage Guide

Supported JSON Schema keywords

  • type — string, number, integer, boolean, object, array, null
  • required — array of required property names
  • properties — nested schemas for each property
  • minLength / maxLength — string length constraints
  • minimum / maximum — numeric range constraints
  • enum — allowed values list
  • pattern — regex pattern for strings
  • items — schema for array items

Example Schema

{
  "type": "object",
  "required": ["email", "role"],
  "properties": {
    "email": {"type": "string", "pattern": "^.+@.+\\..+$"},
    "role": {"type": "string", "enum": ["admin","user","guest"]},
    "score": {"type": "number", "minimum": 0, "maximum": 100}
  }
}

Query String Parser & Builder

Parse a URL’s query string into key-value pairs, or build a query string from parameters.

Usage Guide

Parse Mode

  • Paste a full URL or just a query string (e.g. ?a=1&b=2).
  • Values are automatically URL-decoded in the results table.

Build Mode

  • Enter a base URL and add key-value parameter pairs.
  • Check URL-encode values to automatically encode special characters.

Example

https://api.example.com/search?q=hello%20world&limit=10&offset=0