Form Data Inspector
Paste query strings, application/x-www-form-urlencoded bodies, JSON objects, or key-value lines and inspect the exact form fields before shipping an API request. Detects duplicate names, blank values, encoded characters, and produces URLSearchParams, FormData, cURL, and a copyable request checklist in your browser.
Runs in your browser
Nothing uploaded
Free, no signup
Ctrl + Enter to run · Recent brings back your last inputs · Everything stays in this browser
Form Data Inspector: questions
What can I paste into Form Data Inspector?
Paste a query string, a URL with query parameters, an application/x-www-form-urlencoded request body, a JSON object, or one key=value pair per line.
Does it upload my payload?
No. Parsing and export generation run entirely in your browser.
Why do duplicate form fields matter?
Many APIs and frameworks treat duplicate field names differently. This tool shows every occurrence so you can decide whether arrays, repeated checkboxes, or accidental duplicates are safe.
How does this fit with cURL to Fetch?
Use cURL to Fetch to capture the whole request, then use Form Data Inspector when the body or query string needs review before turning it into URLSearchParams, FormData, or a test fixture.
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