Selling a search whose negative result means nothing

The 402 layer is the family’s. The problem here is that the underlying question is fuzzy and the API returns something that looks crisp.

Trademark conflict turns on confusing similarity, not string equality. A mark that is not identical can still infringe if consumers would confuse the two, which means an exact-match query over a trademark database returns clean results answering a question nobody asked. Someone searching their proposed brand name and getting nothing reads that as “clear”, and it is not.

Doing better means phonetic matching, since marks that sound alike are confusable regardless of spelling, plus edit distance for near-misses, both of which bring false positives needing judgment to filter. Even a perfect text search misses design marks entirely, because a logo can be confusable with another logo sharing no text. Classification is the other layer: the same word can be registered by different parties in different Nice classes without conflict.

Which leaves the honest position. This can tell you what is definitely already registered and cannot tell you that you are clear. Returning a clean empty result sells false confidence about something with legal consequences, and communicating that uncertainty in a JSON response is the actual design problem.