26 Developer Utilities Online — Free, Privacy-First
26 dev tools + Vietnam-specific tools: JSON/SQL/XML/YAML formatter, JWT/Hash/UUID/Cron/Curl, Password gen, Lorem Ipsum (+VN literature), Chmod, JSON↔CSV, HTTP Status + 4 unique VN tools (CCCD/Tax/Address/Holidays). 100% in browser, no signup.
Pick a tool
Format / Validate / Minify / Escape JSON with line + column error display.
UTF-8 safe Base64 encode/decode + URL-safe mode + file support.
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.
UUID v4 / v7 / nanoid / ULID — bulk 1-100, uppercase + no-dashes options.
Unix ↔ ISO 8601 ↔ Local + timezone selector + relative time.
MD5 + SHA-1 + SHA-256 + SHA-384 + SHA-512 simultaneously + HMAC + file hash.
Encode/decode + URL parser breaking protocol/host/path/query.
Live highlight matches + capture groups + 7 common pattern cheatsheet.
Decode header + payload + signature. Shows formatted exp/iat + claims explained.
Format, validate, minify XML + XML ↔ JSON converter with inline error display.
Format SQL for MySQL, PostgreSQL, T-SQL, BigQuery, Snowflake — 20+ dialects supported.
HEX ↔ RGB ↔ HSL ↔ HSV + opacity slider + Tailwind palette quick-pick.
Bidirectional JSON ↔ CSV conversion with custom delimiters (comma/semicolon/tab/pipe).
Convert Linux/Unix permissions between octal (755), symbolic (rwxr-xr-x) + interactive table + 8 presets.
Reference for 40+ HTTP status codes (100-511) with detailed descriptions + category filter + realtime search.
Convert numbers between binary, octal, decimal, hex with unlimited-digit BigInt support.
Parse cron expressions to plain English + predict 7 next runs + 10 common presets.
Convert curl commands to fetch / axios / Python / Go / Java / PHP / Ruby / Rust / C# / 14 languages.
Convert JSON to YAML and back with inline error highlight.
camelCase / PascalCase / snake_case / kebab-case / CONSTANT_CASE — 9 formats at once.
Word / char / line level diff with highlights + added/removed/unchanged stats.
🇻🇳 Business day calculator that subtracts Vietnamese lunar Tết + Hùng Vương Memorial + 30/4 + 2/9. 2020-2030 holiday DB.
🇻🇳 Tax code (MST) checksum validate, citizen ID (CCCD) 12-digit decode (province + gender + birth year), bank account detect.
🇻🇳 Parse Vietnamese addresses into structured JSON {street, ward, district, province} across all 63 provinces.
🇻🇳 Telex→Unicode, remove diacritics, VN slug (đ→d), text stats + Vietnamese collation sort.
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.