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Query String Parser

Parse URL query parameters into readable JSON or rebuild a query string from JSON.

Tool input is processed locally in your browser and is not submitted to CodeNimbleTools. Avoid pasting production secrets into any device or website you do not fully trust.

Input
Result

About this tool

The query part of a URL carries key-value parameters after the question mark, using percent encoding and often repeated keys. The Query String Parser converts a full URL or raw query string into readable JSON and can rebuild a query string from a JSON object.

Repeated parameters such as tag=php&tag=seo may represent an array, while plus signs are commonly decoded as spaces in form-style encoding. The order of parameters usually should not affect server behavior, but signatures and caching systems can be sensitive to normalization. Do not place passwords or long-lived secrets in query strings because URLs are frequently stored in browser history, server logs and analytics systems. For general URL-safe text slugs, use the URL Slug Generator.

How to use it

  1. Select query-to-JSON mode and paste either a full URL or only the text after the question mark.
  2. Keep repeated keys as arrays when the receiving application treats them as multiple values.
  3. Convert and inspect decoded spaces, Unicode characters and empty values.
  4. Switch to JSON-to-query mode when building parameters from a simple object.
  5. Copy the result and test it against the exact framework or API that will parse it.

Useful ways to apply it

  • Inspecting tracking, filter and pagination parameters in a copied URL.
  • Turning an API query into JSON for easier debugging and comparison.
  • Building a correctly percent-encoded query from a small object.
  • Checking how repeated keys and blank values are represented.
  • Finding double-encoding or unexpected plus/space behavior.

Worked example

Example input

https://example.com/search?q=css+grid&tag=layout&tag=responsive

Expected output

{"q":"css grid","tag":["layout","responsive"]}

Edge cases to check

  • Repeated keys can represent arrays or application-specific semantics.
  • Plus is often decoded as a space in form-style query encoding.
  • Nested object conventions are framework-specific.

Known limitations

The parser handles common URL query semantics; it does not claim one universal format for nested query objects.

How this tool was reviewed

Reviewed with repeated keys, empty values, percent-encoding, plus signs and Unicode.

Last reviewed: September 3, 2026 · Maintainer: William

Standards and technical references

See the site-wide testing methodology for fixture categories, privacy checks and correction policy.

Frequently asked questions

What happens to repeated query keys?
With the array option enabled, repeated keys are collected in an array. Without it, a later value may replace the earlier one.
Why does a plus sign become a space?
Application/x-www-form-urlencoded conventions use plus for a space. A literal plus should normally be percent-encoded as %2B.
Can query strings contain nested objects?
There is no single universal nested-query standard. Frameworks use different bracket or dotted conventions, so this tool focuses on simple keys, values and repeated arrays.
Are query parameters safe for secrets?
No. URLs can appear in history, logs, referrer data and monitoring tools. Send secrets through secure headers or request bodies where appropriate.

Privacy

Tool input is processed locally in your browser and is not submitted to CodeNimbleTools. Avoid pasting production secrets into any device or website you do not fully trust.