Query String Parser
Parse any URL or query string into a table of key-value pairs. Handles repeated keys, plus-encoding and percent-encoding.
| Key | Value(s) |
|---|
Pure browser JavaScript — no external libraries.
How to use this tool
- Paste a full URL or just the query string (after ?).
- Click Parse or watch the table update live.
- Repeated keys appear as comma-separated values.
Parse any URL or query string into a table of key-value pairs. Handles repeated keys, plus-encoding and percent-encoding.
How it works
A URL query string is the portion after the '?' character that carries key-value parameters, for example ?page=2&sort=date&filter=active. This tool parses any URL or query string into a structured table of keys and values, making it easy to read all parameters at a glance.
Paste a full URL or just the query string (with or without the leading '?') and the tool decodes percent-encoded characters, handles plus signs as spaces (application/x-www-form-urlencoded), and groups repeated keys (e.g. tag=a&tag=b) into an array.
Common uses include debugging redirect URLs, understanding tracking parameters in marketing links, inspecting search engine result URLs, or auditing parameters sent by a form submission.
Everything runs in your browser -- paste URLs containing auth tokens, session IDs, or personal data without concern about server-side logging.
Worked example
Inspect a marketing link's UTM tracking parameters
- Copy the full URL from a marketing email: https://example.com/landing?utm_source=email&utm_medium=newsletter&utm_campaign=summer2025.
- Paste it into the Query String Parser.
- The tool displays a table: utm_source=email, utm_medium=newsletter, utm_campaign=summer2025.
- You can now see exactly which campaign, medium, and source are being tracked.
A clean table of all UTM parameters and their decoded values.
Common mistakes to avoid
- Expecting array behaviour for a key that appears only once -- single-instance keys return a plain string, not an array. Handle both types in your application code.
- Pasting only the path without the query string (e.g. /search instead of /search?q=hello) -- there is nothing to parse without the '?' and following parameters.
- Forgetting that parameter values can themselves contain encoded characters -- always decode values before processing them in your application.
Key terms
- Query string
- The portion of a URL after the '?' character, containing key-value pairs separated by '&'.
- Percent-encoding
- A URL encoding mechanism that represents special characters as '%' followed by their hex code, e.g. %20 for a space.
- UTM parameter
- Urchin Tracking Module parameters (utm_source, utm_medium, utm_campaign, etc.) added to URLs to track marketing campaign attribution in analytics tools.
Frequently asked questions
- Are + signs decoded?
- Yes — both + (space) and %XX percent-encoding are decoded automatically.