QuestDB

QuestDB is an open-source time-series database designed for high-performance, low-latency data ingestion and querying, capable of ingesting up to 20 million rows per second. It offers a SQL-native interface with time-series extensions such as SAMPLE BY and ASOF JOIN, multi-tier storage that moves data from a hot WAL tier through real-time columnar storage to cold Parquet object storage, and native Parquet and Iceberg support with a REST API for LLM and agent integration. The core database is released under the Apache 2.0 license and built by the QuestDB team with contributions from more than 170 open-source community members; a proprietary Enterprise tier adds high availability, RBAC/TLS/SSO security, 24/7 support, and a 99.9% uptime SLA. It is used by firms including B3, Airbus, and HDFC Bank.