Web & Developer Tools
Small, focused utilities for building and securing things online — encoding, hashing, ID generation, JSON, and more. Each one does exactly one job well.
Encoding & Data
Base64 Encoder / Decoder
Encode or decode Base64 text — Standard (RFC 4648, + / with = padding) or URL-safe (- _, no padding, the variant used in JWTs) — type in either box and the other updates instantly.
URL Encoder / Decoder
Encode or decode a URL component (RFC 3986, spaces as %20) or a form value (application/x-www-form-urlencoded, spaces as +) — type in either box and the other updates instantly.
Hash Generator
Instantly compute SHA-1, SHA-256, SHA-384, and SHA-512 hashes of any text using your browser's built-in crypto.subtle. MD5 isn't offered — it's not part of the Web Crypto API.
JSON Formatter & Validator
Validate JSON against the RFC 8259 spec with exact line/column error reporting, then pretty-print or minify it — with warnings for duplicate keys and unsafe-precision numbers.
Generators
Password Generator
Generate strong, random passwords with your browser's cryptographically secure random number generator, with a real entropy-based strength rating.
UUID Generator
Generate random Version 4 UUIDs (RFC 4122) using your browser's built-in crypto.randomUUID() — bulk-generate, with optional uppercase and no-hyphens formatting.
Slug Generator
Type a title to get a clean, URL-safe slug instantly — lowercased, accents stripped (café → cafe), punctuation collapsed into a hyphen or underscore.
Lorem Ipsum Generator
Generate Lorem Ipsum placeholder text by paragraphs, sentences, or words.
Developer Utilities
JWT Decoder
Decode a JSON Web Token’s header and payload. This tool never verifies the signature — decoding is not proof a token is valid.
Regex Tester
Test a regular expression against your own text with live match highlighting, capture groups, and named groups.
Cron Expression Parser
Parse a standard 5-field cron expression into a plain-English schedule.
WCAG Contrast Checker
Check the contrast ratio between two colors against WCAG 2.2 AA and AAA thresholds for normal and large text.
Meta Tag Generator + OG Preview
Generate title, description, Open Graph, and Twitter/X Card meta tags with an approximate search and social preview.
Converters
View all →Markdown → HTML
Paste Markdown to see it rendered live and get the HTML source to copy — CommonMark + GFM tables/strikethrough, raw HTML always shown as text, never executed.
HTML → Markdown
Paste HTML to get clean Markdown instantly — headings, links, lists, code, blockquotes, GFM tables and strikethrough. Script and style content is always dropped.
JSON ⇄ YAML
Convert between JSON and YAML instantly, in either direction — type in either box and the other updates. Reuses the JSON Formatter validator for accurate line/column error messages.
Image
View all →Calculators
View all →Why these tools run entirely in your browser
Passwords, API keys, hashes, and the data you encode or format here are exactly the kind of thing that shouldn't touch a server you don't control. Every tool on this page runs locally in JavaScript — nothing is uploaded, logged, or stored.