Runway API v1 added POST gen4/act-two-voice endpoint for AI voice swapping with Act-Two.

Example

• Runway Act-Two voice swap POST gen4/act-two-voice using Ragnar voice

Original video

curl --location 'https://api.useapi.net/v1/runwayml/gen4/act-two-voice' \
--header 'Authorization: Bearer user:12345-…' \
--header 'Content-Type: application/json' \
--data '{
    "video_assetId": "user:12345-runwayml:…-asset:…",
    "voiceId": "YOq2y2Up4RgXP2HyXjE5"
}'

Result