About URL Decoder

Decode percent-encoded URL strings. Part of the DevTools Surf developer suite. Browse more tools in the Text / String collection.

Use Cases

• Reading encoded redirect chains in OAuth error debugging
• Inspecting UTM tracking parameters in marketing campaign URLs
• Decoding API error messages containing percent-encoded paths
• Understanding encoded deep link URLs from mobile applications

Tips

• Paste encoded URLs from browser address bars to read them
• Decode multiple layers if the URL was double-encoded
• Use this to inspect tracking parameters in marketing URLs

Fun Facts

• Browser address bars automatically decode percent-encoded URLs for display, but send the encoded version to servers.
• The longest valid URL varies by browser: Chrome supports up to 2,083 characters, while most servers limit to 8,192 bytes.
• Punycode, used for internationalized domain names, converts Unicode to ASCII and was standardized in RFC 3492 in 2003.

FAQ

What's percent-encoding?

RFC 3986: each non-ASCII or reserved character is represented as `%` followed by two hex digits of its UTF-8 byte value. `hello world` becomes `hello%20world`.

Does it decode + as space?

Toggle — form-encoded URLs use `+` for spaces (application/x-www-form-urlencoded). Standard URLs use `%20`. The tool handles both.

What about double-encoding?

Detected — if the input is `%2520`, decoding once gives `%20` (still encoded). Run the tool twice or toggle 'aggressive decode' to unwrap all layers.

Are emoji decoded correctly?

Yes — multi-byte UTF-8 sequences (emoji, CJK) reassemble into the original characters. The tool handles 1-, 2-, 3-, and 4-byte encodings.