URL-encode text
Percent-encode text so it is safe to put in a URL.
What to know
Characters that would otherwise have special meaning in a URL are replaced with percent-escapes. This uses the same rules as JavaScript's encodeURIComponent, which is correct for query-string values.
Note that it deliberately does not escape characters like / and : — if you are encoding an entire URL rather than one parameter value, that is what you want.
Questions
Is anything uploaded to a server?
No. Every tool on this site runs inside your browser using standard web APIs. There is no upload, no account, no logging and no server holding your data afterwards. You can confirm it by opening your browser's developer tools and watching the network tab stay empty while you work.