More of a major infastructure provider in vein of Amazon Web Services than a toolkit for building out an app like Firebase is.
Google Firebase is very powerful while being very easy to use. For example, you can run cloud functions, but you don't even need to for most data storage and retrieval or auth. It might be expensive to scale on though.
Netlify is an all-in-one workflow that combines global deployment, continuous integration, and automatic HTTPS. Netlify allows you to build, deploy, and manage, modern web projects with local development, functions and smooth development experience.
Now is a global deployment network built on top of all existing cloud providers. It makes teams productive by removing servers and configuration, giving you a seamless developer experience to build modern scalable web apps.