15 Best Free Developer Tools
Every tool a developer needs — no signup, no ads, no data sent to servers. All run entirely in your browser.
Most "free" developer tools either require signup, show ads, or send your data to a server. Every tool below runs 100% client-side — your code, keys, and files never leave your machine. Bookmark this page.
JSON Formatter
Beautify, validate, and minify JSON with line-number error reports. The tool developers reach for daily.
Regex Tester
Test regular expressions with live highlighting and capture groups. Alternate match colours help you read patterns.
Base64 Encoder / Decoder
Encode text, files, and images to Base64 or decode back. Includes URL-safe mode and full UTF-8 support.
Unix Timestamp Converter
Convert epoch to date and back. Live clock, batch mode, and six output formats including ISO 8601.
Word Counter
Live word, character, sentence count with reading time and keyword density. Essential for technical writing.
QR Code Generator
Generate QR codes for URLs, text, WiFi, email, phone, and SMS. Custom sizes and colours, PNG download.
Password Generator
Cryptographically secure random passwords using the Web Crypto API. Not Math.random().
Unit Converter
Convert length, weight, temperature, volume, area, speed, time, and digital storage instantly.
Percentage Calculator
Four modes: X% of Y, X is what % of Y, percentage change, and add/subtract a percent.
Age Calculator
Exact age in years, months, days — plus birthday countdown and total days lived.
BMI Calculator
Body Mass Index with healthy weight range, BMI Prime, and Ponderal Index. Metric and imperial.
Calorie Calculator
Daily calorie needs, BMR, TDEE, and macro breakdown based on your goal.
Loan EMI Calculator
Monthly payments, total interest, and full amortization schedule for any loan.
Compound Interest Calculator
See how your investment grows over time with year-by-year breakdowns.
Currency Converter
Live exchange rates for 200+ currencies. Instant conversion, no ads.
🎯 Why These Tools?
- No signup required. Open and use — no email, no account, no friction.
- No ads. Clean interface, no distractions, no popups.
- 100% browser-based. Your code and data never leave your device.
- Mobile-friendly. Works on any device with a modern browser.
- Fast. No tracking scripts or third-party requests slowing things down.