We don’t have published SLAs for uptime. If you need SLAs because your workplace or a customer requires them, we can guaranty them as part of an enterprise agreement. Almost no one needs that though!
If you’re just trying to get an idea of how reliable the service is, you can dig through our status page: https://status.flyio.net
I expect we’ll start adding things like uptime SLAs as we start targeting bigger customers. I personally think they’re not very useful, but we do a good job keeping things available so we may as well show our work!