How it works
Each platform has a profile endpoint (bluesky/profile, hackernews/user, devto/profile and so on). Their upstream answers look nothing alike, but every one of them comes back with the same canonical names: author.username, author.followers, content.text for the bio. The table under the result lists exactly the fields that platform returned, and the ones it returned as null because the source does not publish them. Nothing is filled in or estimated. See the unified schema and the response envelope.
Each lookup costs one credit and nothing when the profile does not exist. Repeat lookups are answered from cache for free, and the tool tells you when that happened. This viewer runs nine sources; the API has profile endpoints for many more, including ones that need paid data routes and so are not offered in a free tool.