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.
How to choose the right tool
Developer tools are for inspecting, transforming, validating, and generating code-adjacent text without opening a full IDE.
Many tools expect plain text, JSON, HTML, CSS, SQL, Base64, URL-encoded text, or Unix-style permission values.
Choose by need
- Use formatters and validators when a payload is hard to read or may be invalid.
- Use encoders, decoders, hashes, and generators when you need a precise string transformation.
- Use debugging tools for regex checks, headers, user agents, subnets, chmod values, and cron expressions.
Common tasks
- Format JSON before pasting it into a ticket.
- Decode a JWT payload to inspect claims.
- Test a regex or generate UUIDs for sample data.
Popular tools
Jump straight to the most-used tools in this category.
Helpful guides
Short reads that explain the ideas behind these tools.
Choose a tool and get an instant result
BlinkCalc tools are designed to be fast, practical, privacy-conscious, and easy to understand. Many tools process inputs directly in your browser; tools that need a remote request explain that processing on their page.
AI Token Calculator
Estimate AI tokens, words, characters, context usage, and per-request cost for popular AI models.
API Cost Calculator
Estimate AI API costs based on model pricing, token usage, requests, and monthly volume.
Base32 Encoder and Decoder
Encode text to Base32 or decode Base32 strings instantly in your browser.
Base64 Encoder and Decoder
Encode text to Base64 or decode Base64 strings instantly in your browser.
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.
HTML/CSS/JS Minifier
Minify complete HTML pages with inline CSS and JavaScript in one browser-based tool.
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.
Subnet Calculator
Calculate IPv4 subnet details including CIDR, subnet mask, network address, broadcast address, wildcard mask, host range, and usable hosts.
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.
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Math
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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. These developer tools are free and require no sign-up. Many process pasted data locally, while live URL and website checks require a network request disclosed on the tool page.
Do these tools send my data anywhere?
Formatters, encoders, hash generators, and regex testers process their main inputs in the browser. Tools that inspect a public URL or live service may send that URL or request to a remote service; check the disclosure beside the tool input.
Can I use these tools at work?
They are available for personal and commercial use, but follow your workplace policy. Do not submit secrets, private payloads, internal URLs, or credential-bearing links to a tool that requires a remote request.