Binary media types for WebSocket APIs in API Gateway

API Gateway WebSocket APIs don't currently support binary frames in incoming message payloads. If a client app sends a binary frame, API Gateway rejects it and disconnects the client with code 1003.

There is a workaround for this behavior. If the client sends a text-encoded binary data (e.g., base64) as a text frame, you can set the integration's contentHandlingStrategy property to CONVERT_TO_BINARY to convert the payload from base64-encoded string to binary.

To return a route response for a binary payload in non-proxy integrations, you can set the integration response's contentHandlingStrategy property to CONVERT_TO_TEXT to convert the payload from binary to base64-encoded string.