MongoDB supports a combination of shards and replica sets. Each replica set uses a protocol similar to raft for strong consistency. The replicas are a lot better than just active-secondary mirroring

https://docs.mongodb.com/manual/replication/

There's also Atlas which is the hosted version and makes it very easy to scale up https://www.mongodb.com/cloud/atlas

They also just added a free tier if you want to play with that https://docs.mongodb.com/manual/tutorial/atlas-free-tier-set...