Usability testing a prototype usually means a recording service, a consent form, and a data-handling question. This one skips all three.
Mount it in a React or vanilla app, open the app with ?test=1, and testers run scripted tasks while thinking aloud. When they’re done, they download a single HTML file with the replay, synced audio, and a summary an agent can read. No backend and no third-party services. The recorder only loads while testing is active, so everyone else pays about 1 KB.