Free Developer Tools
Fast, free, and private. All tools run 100% in your browser. No data is ever sent to our servers.
No sign-up required · 25 toolsDeveloper Guides
In-depth references for the standards behind these tools.
UUID v4 vs ULID — Which to Choose?
Compare UUID v4 and ULID for distributed systems. Performance, sortability, and use cases.
JWT Anatomy — Header, Payload, Signature
Understand JWT structure, claims, and signing algorithms. Security best practices.
URL Encoding — When to Use What
encodeURI vs encodeURIComponent vs escape. Query strings, paths, and reserved characters.
Hash Algorithms — MD5, SHA-1, SHA-256, bcrypt
When to use each hash function. Security comparison and password storage best practices.
Cron Expression Cheatsheet
Cron syntax reference with common patterns. Quartz vs Linux cron differences.
Regex Lookahead and Lookbehind Explained
Master regex zero-width assertions: positive/negative lookahead and lookbehind.
Unix Timestamp vs ISO 8601 — Which to Use?
Compare Unix timestamps and ISO 8601 dates for storage, APIs, and human readability.
Color Formats — HEX, RGB, HSL, OKLCH
Modern CSS color formats explained. When to use OKLCH for perceptual uniformity.
HTTP Status Codes — Complete Reference (1xx–5xx)
RFC 9110 with real-world API patterns. 401 vs 403, 409 vs 422, 502 vs 503 vs 504.
Your Privacy Matters
We strictly do not store any of your data. Everything is processed locally in your browser using JavaScript. No server-side processing, no cookies, no tracking of your input data.