Query String Parser

What Is a Query String Parser?

A query string parser extracts the parameters from the part of a URL after ? and displays each key and value in a readable form. It can also decode percent-encoded values and represent repeated parameters as structured data.

https://example.com/search?q=shoes&page=2 contains q = shoes and page = 2. How do I parse URL parameters? Paste the URL or the raw query; this tool lists every occurrence without uploading the string.

What Is a Query String?

In https://example.com/search?q=shoes&page=2#results, the path is https://example.com/search, the query string is ?q=shoes&page=2, and the fragment is #results. ? starts the query. & separates parameters. = separates a key from a value when a value is present. A parameter does not have to include =.

How to Use the Query String Parser

1. Paste a full URL or raw query string.
2. The parser extracts the query component and stops before any fragment.
3. Review decoded key/value pairs in original order.
4. Inspect repeated keys, empty values, and flags that have no =.
5. Switch to JSON when you need an object with arrays for duplicates.
6. Copy JSON, the original query, or a normalized query if you need that form.

How Query String Parsing Works

Input is classified as a full URL or a raw query. The query component is taken from URL.search when the input is a URL, otherwise from the text after an optional ?. Pairs are split on unencoded &, the first unencoded = separates key and value, then keys and values are decoded. + becomes a space when the URLSearchParams-style option is on. Repeated names stay as separate rows. JSON is a convenience view: one value stays a string; two or more become an array.

Real examples

API-style: https://api.example.com/users?status=active&limit=20&offset=40&sort=name yields status, limit, offset, and sort as strings. Callback-style: https://example.com/callback?code=abc123&state=xyz is a dummy example—do not paste live OAuth codes into shared screenshots.

What Happens When a Query Parameter Appears More Than Once?

?tag=js&tag=react contains two occurrences. This parser keeps both. Languages and frameworks may collapse duplicates, last-write-win, or build arrays. Bracket forms such as tags[]=javascript are shown as the literal key tags[]; that notation is not a universal array standard. The table is the safest record of what the URL actually contained.

URL Encoding and Decoding

Spaces often appear as hello%20world or, in form-encoded queries, hello+world. / is %2F, ? is %3F, & is %26, and = is %3D. How do I decode URL parameters? The default here follows URLSearchParams: + is a space. Turn that option off if a plus must stay literal.

Query String Parser vs URL Parser

Query String Parsing in JavaScript

URLSearchParams is the browser-native API for query strings:

const url = new URL("https://example.com/search?q=tools&page=2");
const params = url.searchParams;
for (const [key, value] of params) {
  console.log(key, value);
}

That logs q → tools and page → 2.

Common Uses for a Query String Parser

• Debugging API query parameters and frontend-generated search or filter URLs.
• Inspecting pagination, sort, and callback URLs during QA.
• Reading UTM and other tracking links without treating this page as analytics software.
• Converting query parameters to JSON for a ticket or a test fixture.
• Comparing raw and decoded values when a redirect looks wrong.

Common Query String Parsing Mistakes

• Splitting on & after decoding, which can break encoded values.
• Splitting on every = instead of the first separator in a pair.
• Dropping repeated keys or empty values.
• Treating a fragment as part of the query.
• Forgetting percent-decoding, or assuming + is always a literal plus.
• Assuming every framework interprets duplicates the same way.
• Reordering or re-encoding signed URLs.
• Sharing tokens or API keys that were sitting in the query.

Query string parser FAQ