How to Trim MP4 Video Locally in Browser Without Re-encoding (Zero Uploads)

Traditional cloud converters for MP4 video trimming and JWT signature verification introduce significant latency and security risks. Users often face bandwidth waste and privacy exposure when uploading confidential recordings or sensitive backend signing secrets to third-party servers. These cloud tools may log inbound HTTP payloads, potentially archiving live session tokens. To mitigate these risks, architectural alternatives like in-browser Stream Copying and local memory inspection allow developers to process data without server uploads, ensuring better compliance and privacy.