8 tiny tools developers use daily, free, private, in your browser
JSON Formatter & Validator
Paste messy JSON, get pretty output + error location.
Waiting for input...
// formatted JSON appears here
Base64 Encode / Decode
UTF-8 safe. Text or small files, all local.
Waiting for input...
URL Encoder / Decoder
Full URL or component encoding, query-safe.
Waiting for input...
JWT Decoder
Decodes header & payload locally. Signature is NOT verified.
Waiting for token...
Header
-
Payload
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Timestamp Converter
Unix to/from human date, UTC + local, ISO 8601.
Now:...
Result appears here
Result appears here
Hash Generator
SHA-1 / 256 / 384 / 512 via WebCrypto. Nothing leaves your browser.
Pick an algorithm...
UUID Generator
Crypto-random v4 UUIDs, bulk ready.
// click Generate
Password Generator
Crypto-random, generated locally, never sent anywhere.
click Generate
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Free Online Developer Tools
Eight everyday tools on one fast page. Everything runs locally in your browser with the WebCrypto API, your data is never uploaded, logged, or tracked.
Included Tools
JSON Formatter: Pretty-print, validate with line numbers, and minify JSON
Base64: UTF-8-safe text encode/decode plus small-file encoding
URL Encoder: Full-URL and component encoding/decoding
Password Generator: Crypto-random passwords with entropy meter
Why Use Joulezy Dev Tools?
100% Private: No server calls, tokens, secrets, and payloads stay on your device
Fast: One lightweight page, no login, no ads, keyboard friendly
Free Forever: No quotas, no watermarks, works offline once loaded
Frequently Asked Questions
Safer than most online decoders: decoding happens entirely in your browser with JavaScript, nothing is uploaded. Still, avoid pasting production secrets on any shared computer.
No, it only base64-decodes the header and payload for inspection (including exp/iat human dates). Always verify signatures on your own server.
Yes, they use crypto.getRandomValues (CSPRNG), not Math.random. An entropy estimate is shown so you can judge strength.