Is anything I paste here sent to a server?

No. Every tool on this page runs entirely in your browser with built-in APIs (btoa/atob, encodeURIComponent, JSON.parse, crypto.randomUUID). That makes them safe for tokens, keys and private payloads.

Which encoding do I need for a query string?

Percent-encoding via the URL encoder (encodeURIComponent for a single value). Base64 is for carrying binary data as text, and HTML entities are for showing code or special characters inside an HTML page — each solves a different problem.

Tools & Games

Developer Tools

Base64, URL and HTML encoding, JSON formatting and UUIDs — all in the browser. · 5 tools

Small, fast utilities for everyday development work: the encoders and decoders you need when debugging a request, a JSON formatter that pinpoints the exact line of a syntax error, and a UUID generator backed by the browser’s cryptographic random source. Pair them with the Unix timestamp, binary and number base converters in the Converters section.

Base64 Encode & Decode OnlineFree Base64 encoder and decoder: convert text to Base64 and Base64 back to text (UTF-8 safe), URL-safe…HTML Encoder & DecoderFree HTML encoder and decoder: escape < > & " ' as HTML entities so code shows as text, optionally encode…JSON Formatter, Validator & Minifier OnlineFree JSON formatter: pretty-print JSON with 2 or 4 spaces or tabs, validate it with the exact error line and…URL Encoder & DecoderFree URL encoder and decoder: percent-encode text for query strings (encodeURIComponent) or whole URLs…UUID GeneratorFree UUID generator: create one or hundreds of version 4 (random) or version 7 (time-ordered) UUIDs/GUIDs…

Developer Tools

Frequently asked questions