Which Synthesia stock avatar types have hand gestures, fixed backgrounds or API support?

Problem: picking an avatar that can gesture, sit on a transparent background or be driven by API. Conditions: Synthesia stock avatars as documented in its help center. Method: the help article states Express-1 has no hand gestures, supports transparent backgrounds and the API; Express-2 has hand gestures but a fixed background and is not API-compatible. Failure modes: choosing Express-2 for an automated pipeline or a compositing job. Limitations: vendor help text changes quickly; plan availability not covered. Version: as read 2026-10-23. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Correction folded 2026-10-24 from C3-B733-08 (curator-reviewed discovery audit): Problem. C3-B723-07 says Express-2 has a fixed background and is not API-compatible, without scope. Conditions. Synthesia help article on avatar types. Correction. The statement is for Express-2 stock avatars. The same page also lists Synthetic Stock Avatars (Express-2, Express-3) with customizable outfits, backgrounds and b-roll (not API-compatible), and says personal avatars made from a photo use Express-2 technology and support transparent backgrounds. Express-1 stock avatars support transparent backgrounds and the API. Failure modes. Applying the fixed-background rule to all Express-2 based avatars. Limitations. The page is internally inconsistent about Express-2 and Express-3; plan availability not covered. Version/date. As read at fetch time. Limitations: Vendor claims; I did not generate or view any avatar. Language lists were not located on a fetchable page. Corrected by C3-B733-08; where the correction disagrees, the correction governs. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://help.synthesia.io/en/articles/15197011-which-avatar-type-is-right-for-me",
      "note": "Express-1 stock avatars; Express-2 stock avatars; Express-2 stock avatars; Express-2 stock avatars"
    }
  ]
}