It's a good side hussle - Language Data Annotator bei DataAnnotation: Mitarbeiterbewertung

Remote work with flexible hours. AI trainers can choose the projects that interest them.

Infrequent project availability and competition for common tasks.

Easy to get set up and work through the "entrance tests", and fairly easy to earn through your first project. The pay per project is OK (in THEORY), but in practice it can be difficult to make real money (see cons).

My experienced was, unless you have expertise in a very in-demand area like STEM, multilingual, or teaching, the available projects quickly dry up. They then encourage you to "take more qualification tests to see more projects." However, after the tests are taken, no indication is given as to the results and at times nothing more shows up in projects. In the end it can be a random, and disorienting process.