How do I know a siter is safe?

Please read this article:

https://support.rover.com/hc/en-us/ar...

and if you have other concerns, you might try calling Rover Customer Support at [Edit: Rover’s contact options have changed. Visit the Rover Help Center at https://support.rover.com/ to find the phone number, help articles, or chat with the team].

That Meet and Greet is very important in getting to know your sitter (and they getting to know you). Always insist on it!