%3F is the URL-encoded question mark (?).
In a URL, %3F stands for the question mark (?). Here is when to encode it, what it does in each part of a URL, and what every major language outputs.
Quick facts
| Character | ? |
|---|---|
| Name | Question mark |
| Unicode | U+003F |
| UTF-8 bytes | 3F (1 byte) |
| Percent-encoded | %3F |
| Lowercase form | %3f — identical meaning |
| Double-encoded | %253F |
| HTML form encoding | %3F |
| RFC 3986 class | Reserved — general delimiter |
What it means in a URL
The first raw ? starts the query string. A question mark inside a path segment or inside a parameter value must be encoded as %3F; after the query has started, further raw ? characters are allowed by RFC 3986 but are safer encoded.
RFC 3986 class: Reserved — general delimiter. It marks the structure of a URL (scheme, authority, path, query, fragment), so as data it must be encoded.
When to encode it
| Where it appears | What to do |
|---|---|
| Path segment | Encode |
| Query value | Allowed raw (encoding is also fine) |
| Fragment | Allowed raw |
| Form body | Encode |
The mistake to watch for
A file or page name containing ? (/faq/why?.html): the server sees the path end at why.
What each language produces
Left as-is by JavaScript encodeURI(s); every other function in the table encodes it. Output for the single character, UTF-8 input, tested against the real runtimes (see the encoding comparator for your own strings).
| Function | Output | |
|---|---|---|
| JavaScript encodeURIComponent(s) | %3F | encoded |
| JavaScript encodeURI(s) | ? | kept |
| JavaScript URLSearchParams | %3F | encoded |
| Python urllib.parse.quote(s) | %3F | encoded |
| Python quote(s, safe="") | %3F | encoded |
| Python urllib.parse.quote_plus(s) | %3F | encoded |
| PHP rawurlencode($s) | %3F | encoded |
| PHP urlencode($s) | %3F | encoded |
| Java URLEncoder.encode(s, UTF_8) | %3F | encoded |
| Go url.QueryEscape(s) | %3F | encoded |
| Go url.PathEscape(s) | %3F | encoded |
| Ruby URI.encode_www_form_component(s) | %3F | encoded |
| Ruby ERB::Util.url_encode(s) | %3F | encoded |
| C# / .NET Uri.EscapeDataString(s) | %3F | encoded |
Decoding it
decodeURIComponent('%3F') returns the question mark (?). Python: urllib.parse.unquote('%3F'); PHP: rawurldecode('%3F'). Paste any string into the URL decoder to decode it in your browser.
← %3E Greater-than sign · Full URL encoding table · %40 At sign →
Common questions.
%3F is the percent-encoded form of the question mark (?), whose byte value is 0x3F. Decoding the URL turns it back into the character.
Yes. Hex digits in percent-encoding are case-insensitive, so %3f and %3F mean the same thing. RFC 3986 recommends uppercase, and mixing cases can make caches and analytics count one URL as two.
Use your language’s encoder on the value: encodeURIComponent in JavaScript gives %3F, Python’s quote(s, safe="") gives %3F, PHP’s rawurlencode gives %3F.
More from the toolkit.
About this page. Written and maintained by Sri Murugan Systems, the developer of urlencodedecode.com. Character classes follow RFC 3986 §2; language outputs were generated by running each function in its real runtime.