Free Online Developer Tools
Every encode/decode, format, parse, and convert utility a developer needs — all running in your browser. JSON, YAML, XML, JWT, regex, hashes, timestamps, and more.
25 tools in this category · 100% free · No signup
All Developer Tools
JWT Decoder
Decode JSON Web Tokens (JWT) instantly — inspect the header, payload, and signature claims. Runs entirely in your browser; tokens never leave your device. Safe for production secrets.
Open →JSON Formatter & Validator
Format, validate, and minify JSON instantly. Catches syntax errors with line numbers, pretty-prints with adjustable indent, supports large payloads. Runs in your browser — no upload.
Open →XML Formatter & Beautifier
Format and beautify XML documents — proper indentation, line breaks, namespace handling. Useful for SOAP responses, sitemaps, RSS feeds, and Android resource files.
Open →Base64 Encoder & Decoder
Encode and decode Base64 strings.
Open →URL Encoder & Decoder
Encode/decode URL-safe strings.
Open →HTML Entity Encoder & Decoder
Convert special characters to/from HTML entities.
Open →CSS Minifier
Minify CSS to reduce file size.
Open →HTML Minifier
Strip whitespace and comments from HTML.
Open →JavaScript Minifier
Basic JavaScript minification.
Open →Regex Tester
Test JavaScript regular expressions live.
Open →Hash Generator (MD5/SHA)
Generate MD5, SHA-1, SHA-256, SHA-512 hashes.
Open →UUID Generator
Generate v4 UUIDs.
Open →Unix Timestamp Converter
Convert between Unix timestamps and dates.
Open →Timezone Converter
Convert times between any two time zones.
Open →Cron Expression Builder
Build and explain cron schedule expressions.
Open →YAML to JSON Converter
Convert YAML to JSON in your browser.
Open →JSON to YAML Converter
Convert JSON to YAML format.
Open →JSON to XML Converter
Convert JSON objects to XML markup.
Open →XML to JSON Converter
Convert XML documents to JSON objects.
Open →SQL Formatter
Format and beautify SQL queries.
Open →Text Diff Checker
Compare two text blocks side-by-side.
Open →HTML Formatter
Format and beautify HTML markup.
Open →JavaScript Formatter
Format and beautify JavaScript code.
Open →CSS Formatter
Format and beautify CSS stylesheets.
Open →Base32 Encoder & Decoder
Encode and decode Base32 strings.
Open →Why we built developer tools that run client-side
Pasting a JWT into a random web tool feels wrong — and it should. JWTs, hashes, base64 payloads, and JSON payloads often contain sensitive data: session tokens, API responses, customer records. Every tool on this page that doesn't strictly need a server (which is most of them) runs entirely in your browser using the Web Crypto API, TextEncoder, and the DOMParser. Your data never leaves your device, doesn't show up in our logs, and isn't sent to any third-party API.
What's covered
Encoders/decoders for Base64, Base32, URL, HTML entities. Formatters for JSON, YAML, XML, HTML, CSS, JavaScript, SQL. Converters between JSON↔YAML, JSON↔XML, CSV↔JSON, CSV→SQL. Cryptographic helpers: MD5/SHA hashes, JWT decoder (signature inspection, not validation), UUID v4, timestamp and timezone conversion. Regex tester with live highlighting. Cron expression builder with plain-English explanation.
Are these production-grade?
For dev/debug usage, yes. For build pipelines, prefer purpose-built libraries (Prettier for code formatting, jq for JSON manipulation, etc.) — they handle edge cases that web tools can't (very large files, streaming, plugin systems). But for ad-hoc checks, decoding webhook payloads, formatting a config file you'll paste back in, or sanity-checking a regex against test inputs, these are faster than spinning up a script.