8 developer tools that run entirely in your browser

Format JSON, decode a JWT, test a regular expression, explain a cron expression. No sign-up, no upload, no waiting on a round trip — every tool does its work locally, so whatever you paste stays on your machine.

Nothing leaves your browser
Instant results, no sign-up
⌘KJump to any tool

Formatting

JSON FormatterFormat, validate and minify JSON YAML ⇄ JSON ConverterConvert between YAML and JSON

Encoding

Base64 Encoder / DecoderEncode and decode Base64 and Base64URL JWT DecoderDecode and inspect JSON Web Tokens

Generators

UUID GeneratorGenerate and inspect UUIDs (v4, v7, nil)

Text & Data

Timestamp ConverterConvert Unix time to dates and back Regex TesterTest regular expressions with live match highlighting Cron ParserExplain cron expressions and preview next runs

Why DevTools Hub?

Most online developer utilities send whatever you paste to a server to do the work. For a formatting job that is both slower and riskier than it needs to be — API responses, access tokens and config files routinely contain credentials you would rather not hand to a stranger’s backend.

Every tool here is implemented in JavaScript that runs in your own tab. There is no API behind these pages, no account system and nothing to log. That also makes them fast: results update as you type, and they keep working when your connection does not.

Each tool has its own page with a short explainer, worked examples and answers to the questions that actually come up — so you can check what a cron field means or why a YAML value turned into a boolean without leaving the tool you came for.