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Developer tools.
Format JSON, decode JWTs, generate QR codes, keypairs and passwords.
JSON formatter
Pretty-print, minify and validate JSON with exact error pointers.
HTML / CSS formatter
Tidy indented markup or minify it for shipping. Handles inline CSS and void elements.
Base64 encode
Encode and decode text or files with UTF-8 support and URL-safe mode. Auto-updates as you type.
URL encoder
Percent-encode full URLs or single components, and split query strings into a readable table.
JWT decoder
Read a JWT header and payload offline with expiry checks. Signatures are decoded, never verified here.
QR generator
Text, URL, phone or Wi-Fi credentials to a scannable QR. Download as PNG or SVG.
UUID v4
Bulk RFC-4122 v4 identifiers with cryptographically secure randomness. Copy as list, JSON or CSV.
Password generator
Random or memorable passwords with an entropy meter. Built on WebCrypto randomness.
Keypair generator
RSA, EC (P-256/384/521) and AES keys via WebCrypto. Private keys stay masked until you reveal them.
Timestamp converter
Unix seconds or milliseconds to ISO, UTC and relative time — with automatic unit detection and bulk rows.
JSON to TypeScript
Infer TypeScript interfaces from JSON, with optional Zod schemas. Interface or type-alias output.
Markdown to DOCX
Convert Markdown to a real .docx file with headings, lists, tables and code. Mermaid blocks embed as rendered diagrams.
Markdown to PDF
Markdown to a print-ready PDF with selectable text — styled preview, then your browser's Save as PDF. Mermaid blocks render as diagrams.
JSX to HTML
HTML to JSX is near-lossless; JSX to HTML covers presentational components. Includes a live render check.
Mermaid diagrams
Paste Mermaid code — flowcharts, sequence diagrams and more render live. Export SVG, PNG or JPG, transparent or themed.
Diagram board
Draw an architecture diagram by hand — boxes, arrows, labels — or describe one in a sentence and let your own model sketch it out. Exports SVG and PNG; the board lives in your browser.
Regex tester
Live JavaScript regex matching with flags, capture-group tables and a cheatsheet. Input-capped for safety.
Color contrast
HEX, RGB or HSL pairs checked against WCAG 2.2 — AA/AAA badges plus the nearest passing shade.
Online notepad
Multi-file scratchpad with a folder tree, tabs, autosave and find & replace. Files live in your browser; sign in to sync across devices.