MongoDB - MongoDB (from "humongous") is a scalable, high-performance, open source NoSQL database.
TimescaleDB - TimescaleDB is a time-series SQL database providing fast analytics, scalability, with automated data management on a proven storage engine.
PostgreSQL - PostgreSQL is a powerful, open source object-relational database system.
OpenTSDB - OpenTSDB is a distributed, scalable Time Series Database (TSDB) written on top of HBase.
Beringei - High performance, in-memory storage engine for time series data (by Facebook)
CouchDB - HTTP + JSON document database with Map Reduce views and peer-based replication