Practical debugging guides
Debug browser APIs, headers, cookies, and permissions.
Use these focused workflows to isolate browser-only failures and test the smallest possible change before fixing the underlying application or server configuration.
CORS & APIs · 8 min read
Why Does My API Work in Postman but Fail in the Browser?
Separate CORS, preflight, authentication, cookies, and real server errors when a browser request fails.
Read guide →CORS & APIs · 6 min readHow to Debug CORS Preflight Requests
Inspect OPTIONS requests and compare allowed origins, methods, headers, and credential settings.
Read guide →Authentication & Cookies · 8 min readWhy Does My API Return 401 After Login?
Trace bearer tokens, authentication cookies, refresh flows, browser credentials, and proxies.
Read guide →Authentication & Cookies · 6 min readHow to Test Admin Permissions Without Multiple Accounts
Reproduce role-based access and 403 problems with narrowly scoped test headers and safe local rules.
Read guide →Authentication & Cookies · 5 min readDebug with Header Profiles
Keep local, QA, and staging headers and cookies separate in repeatable browser debugging workflows.
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