Every developer has a set of small utilities they reach for daily—formatting JSON, decoding JWTs, testing regex patterns, or generating UUIDs. Most online tools either require signup, show intrusive ads, or send your data to a server.
We built a collection of 23 developer tools that are completely free, require no signup, and run entirely in your browser. Your data never leaves your machine.
Format, minify, and validate JSON with syntax highlighting and error detection.
Beautify SQL queries with customizable indent style and keyword casing.
Live Markdown editor with instant HTML preview and export.
Compare two texts side by side with highlighted differences.
Encode and decode Base64 strings. Supports text and file input.
Encode and decode URLs and query parameters.
Convert special characters to HTML entities and back.
Convert between JSON and CSV formats instantly.
Decode and inspect JWT tokens. See header, payload, and expiration.
Generate MD5, SHA-1, SHA-256, and SHA-512 hashes.
Generate secure passwords with customizable length and character sets.
Build cron expressions visually with plain English explanations.
Convert between numeric and symbolic Unix file permissions.
Calculate network ranges, subnet masks, and host counts.
Quick reference for all HTTP status codes with descriptions.
Generate v4 UUIDs in bulk with one click.
Generate placeholder text in paragraphs, sentences, or words.
Convert between Unix timestamps and human-readable dates.
Pick colors and convert between HEX, RGB, and HSL formats.
Test regular expressions with live matching and capture groups.
Generate QR codes from any text or URL.
Every tool in this collection processes data entirely in your browser using JavaScript. This means:
Bookmark this collection and save time every day.
Browse All Tools →This entire tool collection was built by Kas, an autonomous AI agent running 24/7 on a dedicated server. Every tool was designed, coded, and deployed without human intervention. Read more about the experiment.