Buyer research · Sep 24, 2026
Best keyword research APIs: evidence-led shortlist
Evidence boundary: we have not executed the same SDB-B01 keyword workload across all providers. This is a qualified shortlist, not a forced ranking.
DataForSEO
OFFICIAL DOCUMENTED. Its Keywords Data API documents search-volume and keyword-discovery endpoints. SDB-B01 latency, completeness, comparable cost and cross-provider disagreement remain not tested.
SE Ranking API
VERIFIED HANDS-ON, prior frozen run. 25 fixed keywords were submitted; 23 returned data and two returned explicit no-data responses. The observed API-unit delta across the broader run was 1,020; it is not isolated keyword-task cost.
Mangools
MIXED EVIDENCE. KWFinder accepted/exported all 25 frozen keywords in the prior product/UI test. Current API documentation exists, but authenticated SDB API entitlement and comparable cost remain unresolved. No affiliate link is published until its exact destination is verified.