URL Query String Inspector
The problem: Long API URLs with URL-encoded parameters are impossible to read or debug by hand — and forgetting to decode them wastes time.
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URL Query String Inspector: the complete guide
A URL query string inspector parses any URL into its structural components — base URL, path, and every query parameter — and displays them in a human-readable, editable table. It then rebuilds the URL live as you add, remove or change parameters, making it the fastest tool available for debugging API calls, building parameterized links, and decoding percent-encoded query values that are unreadable in their raw form. URL encoding turns spaces into %20 or + and reserved characters into two-hex-digit sequences, producing strings like %E2%80%94 that are visually opaque until decoded. This tool makes the structure explicit in one paste.
URL anatomy and percent-encoding
A URL is structured as scheme://host/path?query#fragment. The query component — everything after the ? — is a sequence of key=value pairs joined by & characters. Keys and values undergo percent-encoding to ensure that reserved characters (=, &, +, /, ?, #) can appear inside values without ambiguity. %20 and + both encode a space in query strings; %22 is a double quote; %E2%80%99 is a curly apostrophe in UTF-8. When parameters are nested (as in many analytics and redirect URLs), values themselves contain entire URL-encoded URLs, creating double-encoded sequences that are completely impenetrable without tooling. This inspector decodes all parameters using the URL constructor's searchParams API, which handles all edge cases correctly.
Practical uses: API debugging and link building
Front-end developers use query inspectors most often when debugging API calls copied from the Network tab in DevTools: the raw URL contains dozens of URL-encoded parameters that need to be read and sometimes modified before retrying the request. Marketing teams use them to build UTM-tagged campaign URLs and verify that source, medium, campaign and content parameters are correctly set. SEO professionals inspect redirect chains and canonical URL parameters. QA engineers parse OAuth callback URLs to extract authorization codes, state tokens and scope claims. Because the rebuilt URL updates in real time, changes are immediately visible and copyable.
Step by step: how to use URL Inspector
- 1
Paste any URL into the input field — with or without https:// prefix.
- 2
Click Parse to split the URL into base URL and query parameters.
- 3
Read each parameter key and decoded value in the table below.
- 4
Edit any key or value directly in the table — the Built URL updates in real time.
- 5
Add new parameters with the Add Param button or remove existing ones with the delete icon.
- 6
Copy the final rebuilt URL with the Copy button.
Security & privacy
All URL parsing and rebuilding runs inside your browser using the browser's native URL and URLSearchParams APIs. No URL, no parameter key, and no parameter value is ever sent to a server. URLs can contain authentication tokens, API keys, user IDs and other sensitive data — this tool is safe for all of them because the data never leaves your tab. Verify by opening DevTools Network tab: no requests carry your input.