Developer Tools
Format JSON, validate syntax, decode JWT & Base64, test regex, and generate UUIDs online for free. Zero-latency browser tools.
Software developers, QA engineers, DevOps professionals, and API architects constantly work with structured data formats, authentication tokens, encoded strings, and pattern matching. FreeToolkit's developer suite provides zero-latency, browser-based tools that require no installation, no API keys, and no registration. The JSON Formatter and Validator offer professional-grade editing with 2-space and 4-space indentation options, one-click minification, tree folding, precise syntax error location reporting, and RFC 8259 compliance validation. The Base64 and URL Encoder/Decoder tools handle full UTF-8 Unicode support with live mode switching between encoding and decoding. For security professionals and backend developers, the JWT Decoder inspects token headers, payloads, and signatures with formatted JSON output and human-readable expiration date parsing — all processed client-side so your authentication tokens never leave your machine. The Regex Tester provides interactive JavaScript pattern testing with support for all standard flags (g, i, m, s, u), live match highlighting, and capture group extraction. UUID Generator produces cryptographically secure v4 identifiers using the browser's native crypto.randomUUID() API, with bulk generation options for database seeding and testing workflows.
JSON Formatter
EssentialFormat, prettify, minify, and validate JSON with syntax error tracking.
JSON Validator
Validate JSON syntax and identify precise error locations and unexpected tokens.
Base64 Encoder / Decoder
Encode plain text to Base64 and decode Base64 strings to UTF-8 text.
URL Encoder / Decoder
Encode special characters into percent-encoded URLs or decode URLs to plain text.
UUID Generator
Generate bulk cryptographically secure UUID v4 identifiers.
Regex Tester
Test regular expressions in real-time with regex flag controls and highlighted match results.
Timestamp Converter
Convert Unix timestamps (seconds & milliseconds) to human-readable dates and back.
JWT Decoder
Decode JSON Web Token (JWT) headers and payloads directly in your browser.