15+ free online tools for developers: JSON formatter, Base64, UUID, JWT, hash, password generator, regex tester, LLM cost calculator and more. 100% client-side: your data never leaves the browser.
Format, validate, and minify JSON instantly. Free, fast, and 100% client-side.
Encode text to Base64 or decode Base64 back to text. Supports UTF-8, URL-safe mode, and file encoding.
Generate cryptographically secure UUIDs (v4) in bulk. Copy or export as CSV / JSON.
Decode and inspect JSON Web Tokens. View header, payload, and expiration. No tokens ever leave your browser.
Generate SHA-1, SHA-256, SHA-384 and SHA-512 hashes instantly. Useful for integrity checks and content fingerprinting.
Percent-encode and decode URL components. Handles UTF-8 and reserved characters correctly.
Convert Unix timestamps to human-readable dates and back. Supports seconds, milliseconds, and multiple timezones.
Generate strong, random passwords using your browser's cryptographic RNG. Fully customizable length and character sets.
Generate placeholder text, paragraphs, sentences, or words. Classic Lorem Ipsum for design mockups and prototypes.
Format and beautify SQL queries instantly. Keywords uppercased, predictable indentation, multi-dialect syntax.
Test JavaScript regular expressions live. Highlights matches, captures, and shows errors as you type.
Pick colors and convert between HEX, RGB, HSL and OKLCH. WCAG contrast checker included.
Preview how your page appears on Google, Twitter/X, Facebook, LinkedIn and WhatsApp. Spots missing Open Graph and Twitter Card tags.
Build and decode cron expressions visually. See the next scheduled executions in your timezone.
Convert YAML to JSON and back instantly. Validate YAML syntax and pretty-print JSON output.
Estimate your monthly bill for Claude, GPT, Gemini, DeepSeek and 40+ AI models from your real token usage. Free and 100% client-side.