Developer Tools
JSON, Base64, UUID and other utilities for developers.
Developer utilities format and inspect the payloads you work with daily: JSON, XML, HTML, SQL and API responses. You will also find Base64 and URL encoding, UUID generation, regex testing, JWT decoding, timestamp conversion, and a live HTML/CSS/JS playground.
Formatting and decoding happen in your browser — useful when responses contain tokens, private config or production data you do not want to paste into a random online service.
Reach for the API Tester when you need request/response inspection, the playground for front-end snippets, and the formatters when a log line or SQL dump is too dense to read. Blog posts cover Base64, URL encoding, JSON and SQL formatting in more depth.
Common tasks
- Prettify a one-line JSON log from production
- Decode a JWT header or payload without sending it anywhere
- Generate SQL INSERT statements from spreadsheet rows
- Test a REST endpoint with custom headers and body
Each tool page below includes a working utility plus a short original guide for that job. How we write those guides is on our editorial standards page.
JSON Formatter
Format, validate and minify JSON.
Base64 Encode/Decode
Encode & decode Base64 strings.
UUID Generator
Generate v4 UUIDs.
Regex Tester
Test regular expressions with live match highlighting and groups.
SQL Formatter
Format SQL queries into readable multi-line syntax.
SQL Query Generator
Transform raw multi-line data into clean SQL INSERT or UPDATE statements.
HTML Formatter
Indent and prettify HTML, XML and JSX markup.
API Response Formatter
Paste any API response — auto-detects JSON/XML and prettifies it.
JSON to C# Class Generator
Turn a JSON payload into strongly-typed C# model classes.
JWT Decoder
Decode and inspect JSON Web Tokens securely without sending them to a server.
Timestamp Converter
Convert Unix epoch timestamps to human-readable dates and vice-versa.
Data Format Converter
Instantly convert between JSON, CSV, and Excel formats securely in your browser.
Free API Tester Online (Postman Alternative)
Test REST APIs online with our free API testing tool. Bypass CORS and inspect JSON responses instantly in this fast Postman alternative.
XML Formatter
Pretty-print, validate and minify XML documents in your browser.
URL Encoder / Decoder
Encode and decode URLs with full component and query-string support.
SVG Viewer & Converter
Paste raw SVG code to preview the image instantly, and download it as an SVG or PNG file.
Markdown Converter
Write Markdown with live preview, then copy HTML or download as HTML/PDF.
File Hash Checker
Compute MD5, SHA-256 and SHA-512 hashes of any file entirely in your browser.