Package termination byte in Mavlink

I am trying to parse Mavlink serial messages and I’m having trouble differentiating individual packages. Does Mavlink have a termination byte I can use to identify the end of a package?

Note: I am having to manually build the parser because I am building a Flutter application to received status messages from a Flight Controller. Flutter uses Dart and is, unfortunately, not one of the supported languages: https://mavlink.io/en/#supported_languages