Free online query string builder — construct URL query strings from key-value pairs instantly in your browser. No data is stored. Accepts key=value or key: value format, supports URL encoding, and adds optional leading ? prefix.
Include leading ? in the output
URL-encode the values
Free online query string builder — construct URL query strings from key-value pairs instantly in your browser. No data is stored. Accepts key=value or key: value format, supports URL encoding, and adds optional leading ? prefix.
Runs entirely in your browser. No data is sent to our servers.
Build a URL query string from key-value pairs
Base64 Encode
Free online Base64 encoder — convert text to Base64 format instantly in your browser. No data is stored. Supports UTF-8 text, optional URL-safe encoding, and handles multi-byte characters.
Base64 Decode
Free online Base64 decoder — convert Base64 encoded strings back to plain text instantly in your browser. No data is stored. Supports standard and URL-safe Base64, handles padding, and decodes UTF-8 multi-byte characters.
Base64URL Encode
Free online Base64URL encoder — encode text to URL-safe Base64 format instantly in your browser. No data is stored. Produces RFC 4648 output with -_ instead of +/ and no padding, ideal for JWTs and URL parameters.
Base64URL Decode
Free online Base64URL decoder — decode URL-safe Base64 encoded strings back to text instantly in your browser. No data is stored. Handles RFC 4648 format with -_ characters and missing padding.