Free Online Developer Tools
Small, fast, and free tools for developers and everyday users.
Developer
URL Encoder / Decoder
Encode or decode URLs online for free. Instantly percent-encode special characters or decode %XX sequences in your browser — no data sent to servers.
JSON Formatter & Validator
Format, validate, and minify JSON instantly in your browser. Paste messy JSON and get beautifully indented output with error highlighting. No data sent to servers.
Base64 Encoder / Decoder
Encode text or files to Base64, or decode Base64 strings back to text. Supports data URI output. All processing in your browser.
Character & Word Counter
Count characters, words, lines, bytes, and paragraphs in real time. Includes SNS character limit progress bars for Twitter, Instagram, and more.
chmod Calculator
Calculate Unix file permissions visually. Toggle read/write/execute bits and instantly get the numeric value and chmod command.
Color Code Converter
Convert color codes between HEX, RGB, HSL, and HSB formats instantly. Includes color picker, live preview, and CSS color name detection.
Cron Expression Builder
Build and verify cron expressions visually. See the next 5 execution times, convert to human-readable format, and use common presets.
Image Compressor
Compress JPEG, PNG, and WebP images in your browser. Reduce file size with quality control, batch processing, and ZIP download. No upload to servers.
JSON ↔ YAML Converter
Convert JSON to YAML and YAML to JSON instantly. Configurable indent, real-time conversion, and one-click copy. All processing in your browser.
JWT Decoder
Decode JSON Web Tokens (JWT) instantly in your browser. Inspect header, payload, and expiration without sending tokens to any server.
Loan Calculator
Calculate monthly payments, total interest, and amortization schedule for any loan. Supports equal payment and equal principal repayment methods.
Markdown Preview
Write Markdown and see a live preview side by side. Supports GitHub Flavored Markdown including tables, task lists, and code blocks.
Regex Tester
Test regular expressions in real time with match highlighting. Supports all JavaScript regex flags, named groups, and common presets.
Timezone Converter
Convert times across multiple world timezones simultaneously. 24-hour conversion table with UTC first, work-hours highlighting, and DST awareness.
Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and vice versa. Auto-detects seconds vs milliseconds. Shows UTC and local time with live clock.