redirect_uri
Decoded Value 1
https://example.com/done?step=2
Web
Overview
URL Query Parameter Inspector
Inspect a full URL, decode query values, group duplicate keys, and flag suspicious tracking parameters directly in your browser.
URL Query Parameter Inspector
Inspect a full URL, decode query values, surface duplicate keys, and flag suspicious tracking parameters before they confuse redirects, analytics, or API callbacks.
Tip: press Ctrl/Cmd + Enter to copy normalized output.149 chars
Base URL
https://app.aistacker.dev/callback
Duplicate Keys
1
Risk Signals
2
Normalized Query Output
redirect_uri=https%3A%2F%2Fexample.com%2Fdone%3Fstep%3D2&utm_source=newsletter&utm_source=ads&fbclid=&state=abc123
Parameter Analysis
utm_source
duplicate valuestracking key
Decoded Value 1
newsletter
Decoded Value 2
ads
fbclid
tracking keyempty value
Decoded Value 1
(empty)
state
Decoded Value 1
abc123
What you can solve
How do I find duplicate query parameters in a URL?
Use a query parameter inspector that groups values by key instead of showing the raw query string as one long line. That makes it obvious when the same parameter appears more than once and helps you see whether the duplicate values actually conflict.
How can I decode URL parameter values without breaking the original link?
Decode the values for inspection, but keep a normalized output that preserves the original query structure. That lets you read nested or encoded values clearly while still copying a stable version back into logs or test cases.
Why should I care about empty tracking parameters like fbclid or utm values?
Empty tracking parameters are often a sign that attribution data was appended incorrectly or that a redirect chain stripped the value while leaving the key behind. They may not break the page directly, but they can pollute analytics, make links look suspicious, and hide where the real problem started.
When should I normalize a query string before debugging a redirect issue?
Normalize the query string as soon as you need a clean reference version for logs, support tickets, or side-by-side comparisons. A normalized output removes visual noise and makes it easier to compare what the user clicked with what the app or proxy actually received.
How do I inspect a nested redirect URL inside another query parameter?
Start by parsing the outer URL, then decode the specific parameter that contains the nested link. That sequence helps you avoid double-decoding mistakes and makes it easier to see whether the nested redirect already contains its own query string or tracking baggage.
Typical workflow
Guides for this workflow
Supporting guides that connect this tool to the broader category workflow.
Web guide
encodeURI vs encodeURIComponent for redirect_uri and Query Params
A practical guide to choosing the right encoding boundary for redirect_uri, nested URLs, and query parameter values before a small encoding mistake turns into a redirect bug.
Web guide
Nested Redirect URL Debugging Checklist: Duplicate Params, Empty Trackers, and Decode Boundaries
A practical workflow for debugging redirect URLs that hide duplicate query keys, empty tracking params, and half-decoded nested values.
Web guide
400 vs 401 vs 403 vs 422: A Practical API Error Triage Workflow
A concrete debugging workflow for separating malformed requests, authentication failures, permission issues, and validation errors before your team fixes the wrong thing.
Web guide
Why Access-Control-Allow-Origin Star Fails with Credentials
A practical browser-first guide to diagnosing the most common credentialed CORS mistake: returning wildcard Allow-Origin while the frontend sends cookies or auth-bound credentials.
What is
What is URL Query Parameter Inspector?
A URL Query Parameter Inspector helps developers understand what is really inside a query string before a redirect, callback, or analytics handoff goes wrong. Instead of manually splitting `?foo=bar&foo=baz&utm_source=ads`, you can see duplicate keys, decoded values, empty parameters, and suspicious tracking signals in one pass.
This matters most when a URL looks valid at a glance but still behaves strangely in production. A duplicate `redirect_uri`, an empty `fbclid`, or a half-decoded nested parameter can change routing behavior, pollute attribution data, or hide the actual source of a bug.
How to use
How to use URL Query Parameter Inspector
Paste a complete absolute URL into the input field and let the inspector parse it locally in the browser. Review the decoded parameter values, then check the issue badges for duplicate keys, empty values, and tracking-related signals.
If the URL is valid, use the normalized query output as your clean reference point for debugging logs, support tickets, or documentation. Press Ctrl or Cmd plus Enter when you want to quickly copy the normalized query string.
Example
Example
Input:
https://app.aistacker.dev/callback?redirect_uri=https%3A%2F%2Fexample.com%2Fdone%3Fstep%3D2&utm_source=newsletter&utm_source=ads&fbclid=&state=abc123
Output:
redirect_uri=https%3A%2F%2Fexample.com%2Fdone%3Fstep%3D2&utm_source=newsletter&utm_source=ads&fbclid=&state=abc123Common use cases
Common use cases
1. Debugging redirect and callback URLs that contain nested encoded parameters.
2. Identifying duplicate query keys that change application behavior unexpectedly.
3. Cleaning tracking-heavy URLs before sharing them in docs or support threads.
4. Checking whether empty analytics parameters are leaking into production links.
Frequently asked questions
Frequently asked questions
Does this tool send my URL to a server?v
No. The inspection flow is designed to run entirely in the browser. That makes it safer for internal callback URLs, temporary debug links, and other values you do not want to upload.
Why are duplicate query parameters important?v
Duplicate keys can change how a framework, backend, or third-party service interprets the request. Some runtimes keep the first value, others keep the last, and some preserve the full list, so duplicates are often a hidden source of inconsistent behavior.
Why does the tool mark some parameters as suspicious?v
Suspicious does not always mean malicious. In this inspector it usually means a parameter looks like a tracking key such as `utm_*`, `fbclid`, or another value that is often noisy, empty, or accidentally carried into places where it no longer belongs.