17 Developer Utilities Online — Free, Privacy-First
17 essential developer tools: JSON Formatter, Base64, UUID, Timestamp, Regex Tester, JWT Decoder, Hash (MD5/SHA), Color Converter, Text Diff, YAML, Case Converter, URL Encode + Lorem Ipsum, SQL Formatter, XML Formatter, Password Generator, Chmod Calculator. 100% in browser — no upload, no signup.
Pick a tool
Format / Validate / Minify / Escape JSON with line + column error display.
Format SQL for MySQL, PostgreSQL, T-SQL, BigQuery, Snowflake — 20+ dialects supported.
Format, validate, minify XML + XML ↔ JSON converter with inline error display.
Generate strong random passwords + EFF-style passphrases with crypto.getRandomValues + zxcvbn strength meter.
Generate placeholder text — Lorem Ipsum (Latin), Vietnamese, or Truyen Kieu poetry. For mockups, prototypes, UI tests.
Convert Linux/Unix permissions between octal (755), symbolic (rwxr-xr-x) + interactive table + 8 presets.
UTF-8 safe Base64 encode/decode + URL-safe mode + file support.
Encode/decode + URL parser breaking protocol/host/path/query.
UUID v4 / v7 / nanoid / ULID — bulk 1-100, uppercase + no-dashes options.
Unix ↔ ISO 8601 ↔ Local + timezone selector + relative time.
Live highlight matches + capture groups + 7 common pattern cheatsheet.
Decode header + payload + signature. Shows formatted exp/iat + claims explained.
MD5 + SHA-1 + SHA-256 + SHA-384 + SHA-512 simultaneously + HMAC + file hash.
camelCase / PascalCase / snake_case / kebab-case / CONSTANT_CASE — 9 formats at once.
Word / char / line level diff with highlights + added/removed/unchanged stats.
HEX ↔ RGB ↔ HSL ↔ HSV + opacity slider + Tailwind palette quick-pick.
Convert JSON to YAML and back with inline error highlight.
Why DevTools?
All processing happens in your browser. JWT tokens, secrets, internal JSON never leave your machine. Privacy-first design.
SHA-* hashes use the browser's Web Crypto — faster than JS libs, crypto-safe.
No paywall, no ads, no tracking. One page per tool, 1-click copy.
Vietnamese UI for VN devs + English for global audience. SEO for both languages.
Frequently asked questions
Is data uploaded to a server?
No. 100% client-side via JavaScript + Web Crypto. Disable internet after the page loads and every tool still works.
Does the JWT decoder verify signatures?
No. The client has no server secret to verify. The tool only decodes header + payload + shows the raw signature. For verification, use a server-side tool.
Why isn't MD5 in Web Crypto?
Web Crypto API spec only supports SHA-1, SHA-256, SHA-384, SHA-512. MD5 is deprecated but still used — the tool implements it with a JS lib.
Is there an API to integrate?
Not yet. Phase 1 is web UI only. For programmatic use, install equivalent npm packages.
Is there a dark mode?
Default is dark. A light theme toggle may come later.
Offline (PWA) support?
Not in Phase 1. Phase 2 will add a service worker to cache static assets. For now you need internet for the first load.