Common gotchas when troubleshooting HTTP Request calls to external APIs

[furqanashraf]

Noticed a few threads here lately about HTTP Request issues (variables not expanding in v20+, connection errors with third-party systems, and general request failures). Ran into some of the same pain points myself while testing domain lookup calls, so I wanted to share what helped and get input from others who have debugged this more.

A few things that tripped me up early on:

Variable expansion inside headers vs inside the body behaves differently depending on the version. It's worth testing headers and body separately if a call silently fails, rather than assuming the whole request is broken.
Auth errors often look like connection errors at first glance. If a request "fails" with a vague message, checking the raw response body (not just the Switch log status) usually shows whether it is actually an auth problem.
Testing the same call in Postman first, before wiring it into Switch, saves a lot of back and forth. If Postman works and Switch does not, the issue is almost always in how the request is built inside the flow, not the API itself.

For anyone who wants a simple, free endpoint to practice this debugging process on, [WhoisFreaks](whoisfreaks.com) has a straightforward REST API for domain/WHOIS lookups with a fixed bearer token, no complex auth chain. Useful as a low-stakes way to test variable expansion and error handling before pointing the same setup at a more critical business system.

Curious what others have found. Anyone run into cases where a request worked fine in Postman but failed inside Switch and figured out why?