Developer Tools — zxzx.app
Free online developer utilities: JWT decoder, JSON formatter, SQL formatter, cron expression translator, Unix epoch converter, hash generator, and Base64 encoder/decoder. All tools run in your browser with no data sent to any server.
Available Tools
JWT Decoder — Paste a JWT token to decode its header, payload, and signature. Useful for debugging authentication tokens and API integrations.
JSON Formatter — Format, validate, and minify JSON. Shows error position for invalid JSON. Copy formatted output with one click.
SQL Formatter — Format SQL queries with proper indentation and keyword capitalization. Supports MySQL, PostgreSQL, and SQLite dialects.
Cron Translator — Convert 5-field cron expressions to human-readable descriptions in 5 languages (Korean, English, Japanese, Chinese, Spanish).
Epoch Converter — Convert between Unix timestamps (seconds/milliseconds) and human-readable dates. Bidirectional conversion with timezone support.
Frequently Asked Questions
Is my data sent to a server?
No. All JWT decoding, JSON formatting, SQL formatting, and hash computation happens locally in your browser. Your data never leaves your device.
What hash algorithms are supported?
SHA-256, SHA-512, and MD5 are supported via the Web Crypto API for cryptographically secure hashing.
Can I use these tools for production debugging?
Yes. The JWT decoder and JSON formatter are commonly used for API development and debugging. All processing is client-side so sensitive tokens are safe.