Free online developer utilities. No installation required — all tools run in your browser.
This project is open source under the MIT License.
- JSON Formatter & TypeScript Generator – Format and validate JSON. Generate TypeScript interfaces from JSON. Copy or download output.
- JWT Decoder – Decode and inspect JWT tokens. View header, payload, and expiration.
- Base64 Encoder / Decoder – Encode and decode Base64 strings. Works with text and binary data.
- Unix Timestamp Converter – Convert Unix timestamp to human date and vice versa. Timezone support.
- Cron Expression Parser – Parse cron expressions. Convert to human-readable schedule (e.g. every 5 minutes).
- Regex Tester – Test regular expressions with match highlighting and explanation.
- UUID Generator – Generate UUID v4. Bulk generation and copy to clipboard.
- Markdown Previewer – Preview Markdown as HTML. Export rendered output.
- Diff Checker – Compare two texts or code blocks. Side-by-side and unified views.
- SQL Formatter – Format and beautify SQL queries. Indent and uppercase keywords.
- URL Encoder / Decoder – Encode and decode URL parameters. Percent encoding support.
- Bcrypt Generator – Hash passwords with bcrypt. Compare hashes to verify.
- SHA256 Generator – Generate SHA256 hashes from text. Fast, client-side hashing.
- HTML Entity Encoder – Encode and decode HTML entities (
&,<,>,",'). - Color Converter – Convert between HEX, RGB, and HSL color formats.
- Random Data Generator – Generate random strings, numbers, UUIDs, JSON, and hex.
npm install
npm run devOpen http://localhost:3000.
npm run build
npm start- Copy
.env.exampleto.env.localand setNEXT_PUBLIC_SITE_URLto your production URL (default:https://free-dev-tools.com). - Run
npm run buildandnpm start, or deploy to Vercel/Netlify. - Ensure the site is served over HTTPS (required for clipboard API).
- Set
NEXT_PUBLIC_SITE_URLfor production sitemap, robots.txt, and Open Graph meta. - Each tool has its own page with SEO metadata.