Private Developer Tools for Everyone

Principles

• Local by default

  Tools run in your browser. Your input is processed on your device, not uploaded to a server.

• Nothing stored

  Tool input is kept in memory only. It is not saved, logged or placed in the URL.

• Built for speed

  Pages are prerendered and load only the code each tool needs.

• Base64 Encode / Decode

  Convert text to and from Base64, including the URL-safe variant.

  Runs in your browser

• JSON Formatter

  Pretty-print JSON with 2-space, 4-space or tab indentation, with clear error locations.

  Runs in your browser

• JSON Validator

  Check whether JSON is valid and find the line and column of syntax errors.

  Runs in your browser

• JSON Minifier

  Remove insignificant whitespace from JSON without changing any value or token.

  Runs in your browser

• URL Encode / Decode

  Percent-encode text for use in a URL, or decode percent-encoded text, with full UTF-8 support.

  Runs in your browser

• HTML Encode / Decode

  Escape the HTML special characters & < > " ' as entities, or decode HTML entities back into text.

  Runs in your browser

• UUID Generator

  Generate random version 4 UUIDs with your browser's cryptographically secure random number generator.

  Runs in your browser

• Hash Generator

  Compute SHA-256, SHA-384 or SHA-512 hashes of text with your browser's Web Crypto API.

  Runs in your browser

• JWT Decoder

  Decode and inspect a JWT's header and payload locally. Decoding does not verify the signature.

  Runs in your browser

• Timestamp Converter

  Convert Unix timestamps in seconds or milliseconds to UTC dates, and ISO 8601 dates back to Unix time.

  Runs in your browser

• Password Generator

  Generate random passwords from the character types you choose, using your browser's secure random number generator.

  Runs in your browser

• CSV ↔ JSON Converter

  Convert CSV with a header row to a JSON array of objects, and JSON arrays of objects back to CSV.

  Runs in your browser

• JSON to TypeScript

  Generate TypeScript interfaces from a JSON sample, with optional properties and union types.

  Runs in your browser

• Text Diff

  Compare two texts line by line and see exactly which lines were added, removed or kept.

  Runs in your browser

• Cron Expression Explainer

  Explain a standard 5-field cron expression in plain English, field by field.

  Runs in your browser

• Regex Tester

  Test JavaScript regular expressions against text with live match highlighting and capture groups.

  Runs in your browser

• Markdown Preview

  Preview Markdown as you type: headings, lists, tables, task lists and code blocks, without running any HTML.

  Runs in your browser

• YAML ↔ JSON Converter

  Convert YAML 1.2 to JSON and JSON back to YAML, with strict, documented rules for anchors, merge keys and numbers.

  Runs in your browser

• JWT Encoder & Verifier

  Sign a JWT from header and payload JSON, or verify a token's signature, with HS, RS, PS and ES algorithms.

  Runs in your browser