InfluxDB

InfluxDB is the time-series database you've probably already heard of. It's built for metrics, events, and IoT data — anything with a timestamp. The query language (Flux, now moving to SQL) and built-in downsampling make it the default choice for monitoring stacks.

If you're tracking server metrics, sensor data, or application performance, InfluxDB handles the write-heavy workload that regular databases choke on. TimescaleDB extends Postgres with time-series superpowers and lets you keep one database. Prometheus is the standard for pull-based metrics but isn't a general-purpose time-series DB. Datadog does it all as a service but costs a fortune.

Best for IoT projects, custom monitoring dashboards, or any system generating high-frequency timestamped data.

The catch: InfluxDB 3.0 was rewritten in Rust and dropped Flux for SQL — a massive breaking change from v2. The open source version of v3 is more limited than the commercial offering. If you built on Flux, you're looking at a migration. And TimescaleDB might be simpler if you already run Postgres.