Developer Tools
Free developer tools for everyday web work
Format JSON, decode JWTs, encode and decode Base64, generate UUIDs and prepare URL-safe strings directly in your browser. These tools are designed for quick checks, debugging sessions and daily web development workflows.
Available developer tools
JWT Decoder
Decode the header and payload of a JSON Web Token directly in your browser.
LLM Token Estimator
Estimate token usage and approximate cost for text used with AI models.
JSON Formatter
Format, validate, minify and copy JSON directly in your browser.
Base64 Encoder/Decoder
Encode and decode Base64 directly in your browser.
Unix Timestamp Converter
Convert Unix timestamps to readable dates and back.
ISO8601 Validator
Validate ISO8601 dates and datetimes, inspect timezone offsets and convert to UTC and Unix timestamps.
URL Encoder/Decoder
Encode and decode URLs for query strings, APIs and redirects.
UUID Generator
Generate UUID v4 identifiers for APIs, databases, tests and software development.
Fast browser-based utilities for developers
Small developer utilities are most useful when they are fast, private and easy to reach. CalcolaFacile keeps common web development tasks in one place, so you can inspect data, transform strings and generate identifiers without sending unnecessary information to external services.