URL Encoder and Decoder for Query String Values

What is URL encoding?

URLs can only carry a limited set of characters. Everything else — spaces, &, ?, =, #, /, non-ASCII text — must be percent-encoded: each byte becomes % followed by two hex digits, so a space becomes %20 and é becomes %C3%A9. Without it, a & inside a query value splits the parameter in two and a # silently truncates everything after it.

This tool wraps JavaScript's encodeURIComponent and decodeURIComponent — the strict component-level functions that encode every reserved character, which is what you want for a single query-string value or path segment. Both directions run entirely in your browser; nothing you paste is uploaded or logged.

When to use it

Encode when you're building a URL by hand and a value contains reserved characters: a redirect_uri for an OAuth flow, a search query with spaces and ampersands, a callback URL nested inside another URL. Decode when you're doing the reverse — reading a %-riddled query string out of an access log, a Referer header, or a tracking link and trying to see the actual values.

Decoding is also the fast way to unwrap layered redirects: marketing and SSO links often encode a URL inside a URL inside a URL, and each pass through the decoder peels off one layer. Once you have a result worth discussing, the "Copy link to this result" button gives you a permalink that restores the exact input and mode for whoever opens it.

Example

Say you need to pass https://app.example.com/callback?next=/dashboard as a redirect_uri parameter. Paste it in encode mode and you get https%3A%2F%2Fapp.example.com%2Fcallback%3Fnext%3D%2Fdashboard — safe to drop into another URL because the ?, = and / can no longer be misread as structure of the outer URL. Paste that blob back in decode mode and the original returns, confirming nothing was mangled.