I'm a bit surprised at the negativity here. I have used Firebase for 11 projects and have had no issues at all. I love that I can quickly and easily set up services that work well together.

For most projects I use the realtime database and authentication. The database is very fast and the realtime feature is essential for some of my projects. Authentication is free no matter how many monthly users I have.

I also use storage and hosting, where I get excellent performance.

All but one of my projects work within the free tier. The one project that sometimes exceeds the free tier is generally less than $1 per month. My projects are fairly small, but I know that for large projects, there might be more economical solutions somewhere else.

For me, I would highly recommend Firebase to other developers.