Guides JP

Query String Converter Tool

Parse a URL query string (after ?) into a key/value table and JSON, and build it back from JSON. Supports arrays and duplicate keys.

Last updated: 2026/10/16 Developer Feedback & bug reports
Query String to Table / JSON

You can paste a full URL. The part after ? is extracted and URL-decoded automatically.

Enter a query string to see the table and JSON here.
JSON to Query String

Array values produce repeated keys (e.g. tag=php&tag=web).

Enter JSON to generate a query string here.

How to Use

1

Paste a Query String

Paste a full URL or the query string after ? into the input above.

2

Review Table and JSON

Keys and values are split into a table and JSON automatically. Duplicate keys become arrays.

3

Copy or Reverse

Copy the results, or use the section below to rebuild a query string from JSON.

About the Query String Converter

A web tool that converts the query string (parameters after ? in a URL) into a readable key/value table and JSON, and builds a query string back from JSON. It handles URL decoding, arrays, and duplicate keys, making it useful for debugging APIs, generating links, and inspecting tracking parameters. All processing happens entirely in your browser.

Features

  • Two-way ConversionConvert query string to table/JSON and JSON back to query string.
  • Table & JSON ViewSee keys and values as a clear table and as copyable JSON at once.
  • Arrays & Duplicate KeysRepeated keys are grouped into arrays and expanded correctly on rebuild.
  • Runs in Your BrowserPowered by URLSearchParams. Your input is never sent to a server.

Use Cases

  • Inspect and debug API request URL parameters
  • Check UTM and other tracking parameters
  • Generate link URLs from JSON config
  • Verify URL decoding of non-ASCII queries
  • Design search form and filter parameters

FAQ

Can I paste a full URL?
Yes. When you paste a full URL, only the query string after ? is extracted and parsed. The path before ? and any fragment after # are ignored.
What happens with duplicate keys?
Duplicate keys are grouped into an array. For example, tag=php&tag=web becomes "tag": ["php", "web"] in JSON. On reverse conversion, array values are expanded back into repeated keys.
Are URL-encoded characters decoded?
Yes. Encoded values such as %2F or non-ASCII characters are decoded for display. When building a query string from JSON, characters are encoded automatically as needed.
Can JSON values be numbers or objects?
Numbers and booleans are output as strings. Array values repeat the key, and nested objects are embedded as JSON strings. The top level must be a { } object.
Is my URL or data sent to a server?
No. All conversion runs entirely in your browser (using JavaScript URLSearchParams), and your input is never sent to or stored on any server, so internal URLs and links with tokens are safe to use.

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Related Guides

What Is a Query String? The ?key=value Structure, Multiple Values, and Percent-Encoding Learn what a query string (query parameters) is from the ground up: the ?key=value&... structure, how to express multiple values and arrays, percent-encoding, how it is used with GET, and design pitfalls such as order, duplication, and length.