DevAll tools
Free, no sign-up, and local-only: your input never leaves this page.
Data formats
JSON Formatter & Validator
Format, validate and inspect JSON in your browser, with precise error locations and a collapsible tree view.
JSON Checker
Check JSON for syntax errors and get the exact line and column of the first problem — validation only, nothing rewritten, nothing uploaded.
JSON to XML Converter
Convert JSON to clean, indented XML in your browser — with predictable element naming rules and a report of any key that had to be renamed.
JSON Editor
Edit JSON in a syntax-highlighting editor with live error markers, then format, minify and download — entirely in your browser.
JSON to YAML Converter
Convert JSON to YAML and YAML back to JSON in your browser — full YAML 1.2 parsing, comments and anchors handled, nothing uploaded.
JSON to CSV / CSV to JSON Converter
Turn JSON arrays into CSV tables and CSV files back into JSON — with a live table preview, quoting done properly, all in your browser.
JSON to TypeScript Converter
Turn a JSON sample into TypeScript interfaces — nested objects named and deduplicated, array shapes merged, optional fields detected — in your browser.
Encoding & tokens
Base64 Encoder / Decoder
Encode text to Base64 or decode Base64 back to text — UTF-8 safe, with a URL-safe variant, entirely in your browser.
URL Encoder / Decoder
Percent-encode text for URLs or decode percent-encoded strings — with component and full-URL modes and precise error locations.
JWT Decoder
Decode a JSON Web Token's header and payload, read every claim in plain language, and spot expiry problems — decoding only, never verification.
Network & time
Unix Timestamp Converter
Convert Unix timestamps to human-readable dates (and back) in UTC and your local time zone, seconds or milliseconds.
Subnet Calculator
Calculate network address, broadcast, usable host range, netmask and wildcard from any IPv4 CIDR — with the binary breakdown shown.
What's My IP & Browser Info
See the public IP address the internet sees for your connection, its approximate location and ISP — plus the browser, screen and local-network details this device reports.
Text & generators
Regex Tester
Test regular expressions against your text with every match highlighted, a full match list and capture groups — plus one-click patterns for emails, URLs and dates.
Text Diff Checker
Compare two texts line by line and see exactly what was added and removed — colour-blind-safe markup with + and − signs, all in your browser.
UUID Generator
Generate random UUID v4 values in bulk — up to 100 at a time, with case and hyphen options — using your browser's cryptographic random source.
Hash Generator
Calculate MD5, SHA-1, SHA-256 and SHA-512 digests of any text as you type. Your input is hashed locally and never saved.
Color Converter
Convert colours between HEX, RGB, HSL and HSV with a live preview and one-click copy for every format — paste any notation, get all four.
More tools on the way
This toolbox grows one tool at a time, and every tool ships with a full written guide explaining how the underlying format or protocol works — no empty shells. If a tool you need is missing, tell us: reader requests decide what gets built next.