Developer Tools Calculators

Quick utilities for daily development work: color conversion, CSS units, aspect ratios, bandwidth math, IP subnetting, Base64, JSON formatting, hashing, file permissions and cron schedules. Everything runs locally in your browser — code, passwords and data never leave your machine.

HEX to RGB ConverterHEX ↔ RGB ↔ HSL with a live color preview. Pixel to REM ConverterPixels ↔ rem/em with adjustable root font size. Aspect Ratio CalculatorKeep proportions: solve missing width, height or ratio. Download Time CalculatorDownload/upload time from file size and speed. Subnet CalculatorCIDR → netmask, network, broadcast and host range. Password Strength CheckerEntropy and estimated crack time — checked locally. Base64 Encoder / DecoderEncode text to Base64 or decode it back. JSON Formatter & ValidatorBeautify, minify and validate JSON — with error locations. Hash GeneratorSHA-256 / SHA-1 / SHA-512 hashes, generated locally. Chmod CalculatorPermission checkboxes ↔ chmod octal (755, 644…). Cron Expression GeneratorExplain any cron expression in plain English. PPI CalculatorPPI, dot pitch and density from resolution + size.