Format, convert & decode, without uploading
A focused set of browser utilities for working with JSON, YAML, CSV, regex, JWT, hashes and more. Ideal for sensitive payloads — code, API responses, secrets — because nothing leaves your device.
Pick a tool
JSON Formatter & Validator
Pretty-print, minify, sort keys and validate JSON. Tree view for navigation.
Live Open toolJSON ↔ CSV
Convert a JSON array of objects to CSV and back. Custom delimiters and field selection.
Live Open toolJSON ↔ YAML
Convert JSON to YAML and YAML to JSON. Two-way conversion with format options.
Live Open toolHash Generator
SHA-256, SHA-1, SHA-384 and SHA-512 from text or a file, with checksum compare.
Live Open toolUUID Generator
Bulk UUID v4 and time-ordered v7, from the browser's secure random source.
Live Open toolTimestamp Converter
Unix epoch to date and back, in seconds or milliseconds, UTC or local.
Live Open toolJWT Decoder
Read a token's header, payload and expiry. Nothing is ever transmitted.
Live Open toolFavicon Generator
One image into a full favicon set: real .ico, every PNG size and a manifest.
Live Open toolAbout developer tools
Do you send my code anywhere?
No. Every tool runs entirely in your browser. Your JSON, YAML, CSV, regex, JWTs and hashes are never sent to any server.
What about API testers and Open Graph previews?
Those features would require sending requests to third-party servers and are not part of these tools. Any URL-based tool will say so clearly and explain the CORS limitation.
Is JWT signature verification safe here?
Signature verification with a known secret is safe and local. What no client-side tool can do is tell you whether a token was actually issued by a real authority — that requires asking the issuer. We'll be honest about that on the tool page.