Free Online Developer Tools
Format, validate, encode, decode and generate — the everyday utilities developers reach for, all running privately in your browser.
20 free toolsOnline JavaScript Compiler
Write & run JavaScript in your browser — console output, async, no sign-up
Pomodoro Timer
Online Pomodoro focus timer with custom intervals, stats & a 7-day chart
To-Do List
Rich online to-do list — priorities, due dates, tags, subtasks & progress
Kanban Board
Free online Kanban board — create unlimited boards, drag cards, track progress
JWT Decoder
Decode & inspect JWT tokens — header, payload, claims, expiry
JWT Generator
Create & sign JSON Web Tokens — HS256/384/512, claims builder, expiry
SVG Previewer
Paste SVG to preview live — stats, colors, minify, data-URI/CSS & SVG-to-PNG
Diff Checker
Compare two texts & highlight differences line by line
JSON Validator
Validate JSON with exact error line/column, plain-English fixes & structure stats
JSON Formatter
Beautify, validate, minify & explore JSON with tree view
QR Code Generator
Generate QR codes for URLs, WiFi, contacts, email, phone, SMS & more
Barcode Generator
Generate Code 128, EAN-13, UPC-A, Code 39, ITF-14 & 6 more barcode types
Base64 Encoder / Decoder
Encode & decode Base64 (text & files) with UTF-8 and URL-safe support
URL Encode / Decode
Percent-encode & decode URLs — query params, special chars & Unicode
Password Generator
Create strong random passwords — length, symbols, numbers & strength meter
Hash Generator
Generate SHA-256, SHA-1, SHA-384 & SHA-512 hashes from text or files
UUID Generator
Generate v4, v7, v1, v5 & NIL UUIDs in bulk — formatting, copy & download
HEX to RGB Converter
Convert HEX ↔ RGB instantly with channel breakdown, HSL, CMYK & stats
HEX to HSL Converter
Convert HEX ↔ HSL instantly with hue/saturation/lightness breakdown & lightness scale
Color Picker
Pick colors & convert HEX, RGB, HSL, HSV, CMYK + harmonies & contrast
Beautify and validate JSON, decode and sign JWTs, convert Base64 and URLs, generate UUIDs, preview SVG, diff text and pick colors — no installs, no sign-up, nothing uploaded. These tools keep your tokens, payloads and code on your own machine, which matters when you're debugging real production data.
Frequently Asked Questions
Are these developer tools safe for sensitive data?
Yes. Tools like the JWT decoder, Base64 encoder and JSON formatter run entirely in your browser — your tokens, payloads and code are never uploaded to a server.
Do they work offline?
Once a tool's page has loaded, most work offline because all processing happens client-side in JavaScript.
Are they free for commercial use?
Yes. Every tool is free to use with no limits, including for professional and commercial work.