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? Query String Parser / Builder

Two modes: parse mode takes a query string (with or without leading ?) and produces JSON; build mode takes JSON and produces a URL-encoded query string. Handles arrays, nested keys, and URL encoding automatically.

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Examples

Parse
Input?name=Alice&age=30&tags=a&tags=b
Output{name: "Alice", age: "30", tags: ["a", "b"]}
Build
Input{user: "alice", filter: "active"}
Outputuser=alice&filter=active

Frequently asked questions

How are arrays encoded?

Repeated keys (?tags=a&tags=b). Some APIs use bracket notation (?tags[]=a) — we support both as parse input.

Are values URL-decoded?

Yes — %20 becomes space, %26 becomes &, etc. Build mode encodes back to safe URL characters.

About this tool

Query String Parser / Builder runs entirely in your browser using standard Web APIs. No data is sent to any server. The source for this tool is in our public GitHub repository.

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Why this tool

vs typical free web-tool sites

1vwTypical free site
PriceFreeFree
Signup requiredNoOften (for premium features)
Ads inside the toolNoYes (banner + video)
Data sent to serverNo (browser-only)Yes (inputs analyzed for ads)
Total tools96Often <20 or scattered across sites
Bookmarkable URL per toolYesMixed
Loads in under 1sYes (static)Often slow (ad tracking)
MultilingualEN / ES / PT / FR / DEUsually EN only
Open sourceYesNo