8 Free Developer Tools That Every Programmer Needs

Developer Tools on Metoolzy

Metoolzy offers a suite of 8 developer tools running entirely in the browser — no installation, no account needed. All are free and process client-side.

1. JWT Decoder

JWT Decoder decodes JSON Web Tokens, displays the header, payload, and checks expiration (exp/iat). Does not verify signatures — secure because tokens are not sent anywhere.

2. UUID Generator

UUID Generator generates UUID v4 using crypto.randomUUID(). Supports bulk generation of up to 100 UUIDs, uppercase options, and copying individually or all.

3. Regex Tester

Regex Tester tests regular expressions with real-time match highlighting. Shows capture groups, and supports flags (g, i, m, s).

4. Hash Generator

Hash Generator generates MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes for text or files. Output is in HEX or Base64. Uses Web Crypto API + spark-md5.

5. Timestamp Converter

Timestamp Converter converts Unix timestamps ↔ dates. The live clock displays the current timestamp. Shows Local time, UTC, ISO 8601, and relative time.

6. Cron Expression Parser

Cron Parser parses cron expressions into easy-to-understand English descriptions, showing the next 5 runs.

7. Number Base Converter

Number Base Converter converts between binary, octal, decimal, and hexadecimal. Supports BigInt for extremely large numbers.

8. Code Playground

Code Playground — an HTML/CSS/JS editor using Monaco Editor (VS Code). Live preview, console, external CDN libs, share via URL, and keyboard shortcuts.

Why choose Metoolzy Developer Tools?

• ✅ 100% Client-side — sensitive data (JWT, hashes) never leaves the browser
• ✅ Unlimited — use as much as you want
• ✅ Multilingual — supports 6 languages (VI, EN, JA, ID, ZH, TH)
• ✅ Mobile friendly — works on phones
• ✅ Keyboard shortcuts — Code Playground supports Ctrl+S, Ctrl+1/2/3

👉 See all 65+ Metoolzy tools →