ReallyUseful.Tools

Free web browser tools

Developer Tools

Quick utilities for code, data, and web work. Paste your input, get the result instantly, and nothing leaves your device.

JSON formatter & validator

Format, beautify, validate, and minify JSON online. Pinpoint syntax errors by line and column, sort keys, and copy or download the result.

Color picker & converter

Pick a color and convert between HEX, RGB, HSL, HSV, and CMYK. See tints, shades, and contrast ratios against black and white.

Unix timestamp converter

Convert Unix epoch timestamps to human-readable dates and back. Supports seconds and milliseconds, local time, UTC, and ISO 8601.

Regex tester

Test JavaScript regular expressions with live match highlighting, capture groups, flags, and replace preview.

Number base converter

Convert numbers between binary, octal, decimal, hexadecimal, and any base from 2 to 36. Handles huge integers and negative numbers.

URL encode / decode

Encode or decode URLs and query strings with percent-encoding, and break any URL into its parts and parameters.

JWT decoder

Decode JSON Web Tokens to inspect the header and payload, check expiry, and verify HS256, RS256, and ES256 signatures — tokens never leave your browser.

CSS gradient generator

Design linear, radial, and conic CSS gradients with a live preview. Add color stops, set angles, and copy the CSS.

Cron expression generator

Build and explain cron schedules in plain English. See the next run times, validate expressions, and start from common presets.

SQL formatter

Format and beautify SQL queries for MySQL, PostgreSQL, SQL Server, SQLite, BigQuery, and more. Choose keyword case and indentation.

HTML entity encoder / decoder

Escape special characters as HTML entities or decode entities back to text. Supports named, decimal, and hex entities.