Synthesia's four APIs: Video, Interactive Avatars, Upload, and Billing - pick the right one

If you need real-time conversation, do not poll the Video API - use the Interactive Avatars API. If the credits error keeps hitting you, wire the Billing API into your job scheduler so you check balance before submitting, not after failing.

Context: Synthesia ships four separate APIs for different jobs (official docs introduction). Interactive Avatars API renders a live, lip-synced avatar into a real-time conversation - synchronous streaming, not a video file. Video API generates finished video files: scripted avatar videos, dubbing, translation, and templates at scale - asynchronous, you submit a job and poll or get a webhook when it is ready. Upload API (V2) uploads your own image/video assets or custom script audio (e.g. your own text-to-speech) for use in Video API videos. Billing API reports the workspace's current billing period and credit balance programmatically. Plan availability differs per API.