URL encoding (also called percent-encoding) converts characters into a format safe for transmission over the internet. For example, spaces become %20 and & becomes %26. It's essential when passing data in query strings, form submissions, and API requests.

When to use encoding: API parameters ("?q=hello world" must become "?q=hello%20world"), form data in URLs, constructing safe URLs with user input, embedding special characters in hyperlinks, and preparing data for application/x-www-form-urlencoded payloads.

encode vs encodeURI vs encodeURIComponent — encodeURI() preserves URL structure characters like :/?#[]@!$&'()*+,;= and is meant for full URLs. encodeURIComponent() encodes all special characters including those, making it safe for individual query parameter values. This tool uses encodeURIComponent for maximum safety.

This tool also supports Base64 encoding/decoding (binary-to-text for data URIs, email attachments, API tokens) and HTML entity encoding/decoding (converting < to < for safe HTML rendering). Everything runs client-side — nothing leaves your browser.