Thumbnail A/B testing (Test & compare)

Thumbnail A/B testing shows versions of a video's packaging to different viewers and keeps the winner. YouTube Studio's Test & compare tests up to three titles, thumbnails or combinations on one video, on desktop, and picks the winner by watch time share rather than CTR alone (YouTube Help). Shorts can't be tested this way.

There is no API for it, so tools prepare the variants and you upload them in Studio. SceneGen's packaging pack builds three distinct title + thumbnail pairs and a ready ZIP — see YouTube Test & compare with 3 pairs.