The API requires (or localhost for development) and must be triggered by a user gesture (e.g., button click).
"Support" is not just about the browser; it is also about the operating system and hardware. Here is how each platform affects the API: web serial api browser support
Before analyzing support matrices, let's establish a baseline. The Web Serial API is a JavaScript interface that allows a secure web application (served over HTTPS or from localhost) to request access to a serial port connected to the user's machine. The API requires (or localhost for development) and
Mozilla has made its position clear. In a well-known bug tracker discussion, Mozilla developers marked the Web Serial API as "WONTFIX" (will not fix). Their stated reasoning includes: web serial api browser support