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Query String Parser & Builder
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This query string tool works both ways: paste a query string to parse it into readable key-value pairs, or enter individual parameters to build a properly URL-encoded query string from scratch. It's a practical url params tool for developers wiring up API requests, debugging redirect URLs, or constructing tracking links with UTM parameters. Because it handles encoding and decoding automatically, you don't need to remember which characters require percent-encoding or worry about malformed ampersands. It's useful for backend engineers, frontend developers, and marketers alike who need a reliable url query encoder without opening a code editor. As with every tool here, parsing and building happen instantly in your browser - nothing is uploaded, no signup required. Use the input below to parse an existing query string or assemble a new one parameter by parameter.
Features
- Parses query strings into individual key-value pairs
- Builds URL-encoded query strings from key-value input
- Handles duplicate keys and array-style parameters
- Automatically percent-encodes special characters
- Decodes encoded values for readability when parsing
- Supports both leading '?' and bare query string formats
- Instant two-way conversion with live updates
Why use this query string parser / builder?
- Fast, real-time parsing and building with no delay
- Fully client-side - your parameters are never sent anywhere
- Accurate encoding that follows standard URL encoding rules
- Simple interface usable without technical documentation
- Completely free with no usage caps
Frequently asked questions
What's the difference between this and the URL parser tool?
This tool focuses specifically on the query string portion and also lets you build one, while the URL parser breaks down a full URL into all its components.
Does it handle repeated parameter keys like ?id=1&id=2?
Yes, repeated keys are grouped and displayed as an array of values under that key.
Will it encode spaces as %20 or +?
It uses standard percent-encoding (%20) for spaces, matching the encodeURIComponent behavior in JavaScript.
Can I paste a full URL instead of just the query string?
Yes, the tool will detect and extract the query string portion automatically if a full URL is pasted.
Is nested data supported, like arrays or objects in params?
The tool supports common bracket-style array notation, but query strings are fundamentally flat key-value pairs by spec.
Does building a query string require a leading '?'?
No, the tool generates the raw query string and you can add the leading '?' when appending it to a URL.
Is this safe for building URLs with special characters?
Yes, all reserved and special characters are properly percent-encoded to keep the resulting URL valid.