Regex for URL query parameter
key=value query parameter.
The URL query parameter regex is (?:^|[?&])([^=&]+)=([^&]*) — copy it below, or open it in the explainer for a token-by-token breakdown.
The pattern
(?:^|[?&])([^=&]+)=([^&]*)
What it matches
?name=alice&age=30?q=hello&sort=date
What it doesn't match
plain text=novalue?key (no equals)
Notes & gotchas
Captures key in group 1 and value in group 2. Used to extract specific parameters from a URL. For full URL parsing, use a URL parser instead.
Code in your language
Use the explainer's Code tab to generate ready-to-paste snippets in JavaScript, Python, Java, .NET, Go, Ruby, and PHP for this pattern.
Open in explainer →Token-by-token breakdown
Every part of the pattern, left to right:
| Token | Meaning |
|---|---|
(?: | start of a non-capturing group |
^ | start of string (or line in multiline mode) |
| | OR — try the alternative |
[?&] | any of: “?”, “&” |
) | end of group |
( | start of a capturing group |
[^=&]+ | one or more: any character except “=”, “&” |
) | end of group |
= | literal text “=” |
( | start of a capturing group |
[^&]* | zero or more: any character except “&” |
) | end of group |
About this pattern
Developer-oriented patterns help with code analysis, log parsing, and data transformation. Use these in build scripts, CI tools, IDE search-and-replace, and code review utilities.
Quick usage in different languages
This exact pattern — with the correct escaping and idioms for each language:
- JavaScript:
/(?:^|[?&])([^=&]+)=([^&]*)/.test(value) - Python:
re.match(r"(?:^|[?&])([^=&]+)=([^&]*)", value) - Java:
Pattern.compile("(?:^|[?&])([^=&]+)=([^&]*)").matcher(value).matches() - C# / .NET:
Regex.IsMatch(value, @"(?:^|[?&])([^=&]+)=([^&]*)") - Go:
regexp.MustCompile(`(?:^|[?&])([^=&]+)=([^&]*)`).MatchString(value) - Ruby:
/(?:^|[?&])([^=&]+)=([^&]*)/.match?(value) - PHP:
preg_match('~(?:^|[?&])([^=&]+)=([^&]*)~', $value)
The explainer’s Code tab regenerates these for any pattern you paste, and the downloadable cheat sheet bundles the breakdown, all seven snippets, and the pitfalls below onto one printable page.
Common pitfalls
- Not anchored. Without ^ and $ this can match a substring anywhere in the input — add anchors if you need the whole value to conform.
- Validate beyond format. Matching the format doesn't guarantee the value is real. Confirm the url query parameter against a source of truth (database, API, or checksum) where it matters.
Standards & sources
This pattern is based on the following authoritative specification(s) and issuing authorities. Formats can change — always confirm against the primary source.
Related patterns
More patterns in the Developer category:
- HTTP 5xx (server error)
- Windows environment variable
- HTTP 4xx (client error)
- Linux username
- HTTP 3xx (redirect)
- Git branch name
See also
Browse all 300 patterns in the library, or open this regex in the interactive explainer to see a token-by-token breakdown, test against custom input, and generate code in seven languages.