Use this free query string parser to decode URL parameters, group repeated keys, or build an encoded query string from one key-value pair per line.
{
"utm_source": "newsletter",
"tag": [
"a",
"b"
]
}3 parameters
URL query strings are useful for filters, tracking, and app state, but private tokens should not be shared in public URLs.
Decode URL parameters while debugging filters, search pages, or app links.
Group repeated keys so duplicate values are easy to spot.
Build a correctly encoded query string from plain key-value lines.
Compare UTM links, search URLs, and app-state URLs before sharing.
Turn search-filter URLs into readable JSON for support tickets, QA notes, or API tests.
4 parameters, 1 duplicate key, and tag shown as ["free", "calculator"]
3 parameters, name decoded as "Access Free Tools", and empty kept as a blank value
?q=calculator+tools&category=developer+tools&page=1
Need a slower walkthrough, a related tool, or the full library? These links keep you close to the task you started.
Plain-language answers about when to use the tool, what it does with your inputs, what to double-check, and how privacy works.
Use it when your task matches one of these common needs: Decode URL parameters while debugging filters, search pages, or app links. Group repeated keys so duplicate values are easy to spot. It works best when you already know the text, code, URL, mode, format, or technical setting the page asks for.
In plain language: Parse mode extracts the query part from a full URL, raw query string, or question-mark string, removes hash fragments from raw input, reads the parameters with URLSearchParams, and groups repeated keys as arrays. Build mode reads one key=value line at a time, appends each pair with URLSearchParams, and returns a copy-ready encoded query string. The examples on the page are there so you can compare your inputs with a filled-out example before copying the answer.
Parse query mode: Paste a full URL, a raw query string, or text that starts with a question mark. The tool works on the query part after the question mark. Build query mode: Enter one key=value pair per line. Blank values are allowed when the target app expects an empty parameter. Repeated keys: The parser keeps repeated parameter names visible as arrays in JSON, and build mode lets you repeat the same key on multiple lines. Encoded characters: URLSearchParams decodes query values in parse mode and encodes spaces and special characters when building the output. Private URL data: Treat query strings as shareable URL text, not as a secret place to put tokens, passwords, or customer identifiers.
Read the output next to your original input. If the tool changes format, units, encoding, spacing, or capitalization, compare a small sample before copying the whole result into another app.
Query strings can be logged, shared, or indexed. Do not place passwords, private tokens, or sensitive identifiers in public URLs. Also check the selected mode, input format, encoding, and whether the text includes private keys, passwords, or sensitive data.
Yes. In parse mode you can paste a full URL such as https://example.com/products?tag=free&page=2, a raw string such as tag=free&page=2, or the same string with a leading question mark. The tool extracts and parses the query part.
Repeated keys stay visible. For tag=free&tag=calculator&page=2, the JSON output shows tag as an array with both values, and the duplicate-key count warns you that the same parameter name appeared more than once.
URLSearchParams serializes spaces in query values as plus signs. That is normal for form-style query strings, so q=calculator tools becomes ?q=calculator+tools when the builder returns the URL-ready query.
No. It focuses on the query string: the part after the question mark. It does not break a URL into protocol, host, path, port, and hash fields except when it needs to extract the query section from a full URL.
It appends exactly the keys you enter. Use tag=free and tag=calculator on separate lines for repeated-key arrays, or enter bracket-style keys such as tag[]=free only when the target app expects that convention.
No. The tool runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.