Free Developer Tools
Free online developer tools including JSON formatters, encoders, converters, validators, generators, regex testers, and debugging utilities. No signup, runs in your browser.
Choose a tool and get an instant result
BlinkCalc tools are designed to be fast, practical, privacy-conscious, and easy to understand. Every result is calculated in your browser.
Base32 Encoder and Decoder
Encode text to RFC 4648 Base32 or decode a Base32 string.
Base64 Encoder and Decoder
Encode any text to Base64 or decode Base64 strings back to plain text.
Chmod Calculator
Calculate Unix file permission chmod values visually.
Cron Expression Generator
Build and explain cron schedule expressions visually.
CSS Formatter
Beautify or minify any CSS.
CSS Minifier
Minify any CSS code to reduce file size for production.
Hash Generator
Generate MD5, SHA-1, SHA-256, and SHA-512 hashes from any text.
Hex to Decimal Converter
Convert between hexadecimal, decimal, binary, and octal instantly.
HTML Encoder / Decoder
Encode special characters to HTML entities or decode them back.
HTML Formatter
Instantly format and indent any HTML.
HTML to JSX Converter
Convert any HTML snippet to valid React JSX syntax instantly.
HTTP Headers Viewer
Inspect HTTP response headers for any public URL.
JavaScript Formatter
Format or minify any JavaScript.
JS Minifier
Minify any JavaScript code to reduce file size for production.
JSON Formatter
Paste raw or minified JSON and instantly format it.
JSON Validator
Validate and format any JSON string and see detailed error messages.
JWT Decoder
Decode any JSON Web Token and inspect the header and payload claims.
Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal.
Regex Tester
Test regular expressions against sample text with live match highlighting.
Robots.txt Generator
Generate a valid robots.txt file for your website with common presets.
ROT13 Encoder
Apply ROT13 to any text. Applying ROT13 twice restores the original.
SQL Formatter
Format and beautify any SQL query.
URL Cleaner
Remove tracking parameters and tidy messy URLs.
URL Encoder / Decoder
Encode any text with encodeURIComponent or decode a percent-encoded string.
User Agent Detector
Detect your browser, operating system, device, and user agent string.
UUID Generator
Generate 1–100 cryptographically random UUID v4 identifiers.
Related categories
Math
Use free online math calculators for percentages, fractions, statistics, geometry, equations, number tools, grades, and date calculations.
Finance
Plan loans, savings, investments, salaries, taxes, retirement, budgets, interest, and mortgage payments with free finance calculators.
Health
Calculate BMI, calories, macros, heart rate zones, pregnancy dates, hydration, fitness metrics, body composition, and wellness estimates.
Converters
Convert length, weight, temperature, area, volume, speed, time, energy, data storage, and other common measurement units online.
Date & Time
Free date and time tools to convert Unix timestamps, calculate the difference between dates, count down to a deadline, switch time zones, and convert military time.
Everyday
Practical everyday calculators for paint coverage, concrete and gravel volumes, electricity costs, wind chill, heat index, fuel cost, ABV, and more.
Frequently asked questions
Are these developer tools free to use?
Yes. Every developer tool on BlinkCalc is free, ad-supported, and runs entirely in your browser. There is no sign-up, no upload, and no usage limit.
Do these tools send my data anywhere?
No. JSON formatters, encoders, hash generators, regex testers, and the rest of the developer toolset run client-side. Your text never leaves your device.
Can I use these tools at work?
Yes. They're free for personal and commercial use, and because nothing is sent to a server, they're safe to use on sensitive payloads as long as your browser is trusted.