JSON2Video
Create and edit videos programmatically: watermarks,resizing,slideshows,voice-over,text animations
Create video, image, and interactive app outputs from prompts or source files.
KPainter API is a free Video API that requires apiKey authentication, is served over HTTPS and supports CORS, so it can be called from the browser.
Details from api.kpainter.ai.

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Create and edit videos programmatically: watermarks,resizing,slideshows,voice-over,text animations
API for receiving movie, serial and cast information
The KPainter API is provided by KPainter OpenAPI (api.kpainter.ai).
Yes. The KPainter API is listed in the Video category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The KPainter API uses apiKey authentication, so you need to register for credentials before making requests.
Yes. The KPainter API supports CORS, so front-end JavaScript can call it directly.
Yes. The KPainter API is served over HTTPS, so it's safe to use in production.