Open Source Database
A database is the last piece of your stack you can casually swap, because the data outlives the application and the schema becomes the real contract everything else is written against - which is why the engine you pick today quietly dictates your options for years. The open source databases here, whether relational, columnar, time-series, or vector, keep that storage format and query layer in the open, so migrating, replicating, or auditing your own data never depends on a vendor's permission or pricing.
Elasticsearch
Distributed RESTful search and analytics engine with vector search and near real-time indexing
NocoDB
Self-hostable no-code platform that turns any database into a spreadsheet interface
Meilisearch
Open-source search engine API for hybrid full-text and semantic search in apps and websites
ClickHouse
Open-source column-oriented OLAP database for real-time analytical reports with SQL
Milvus
Cloud-native vector database for scalable ANN search, hybrid search, and real-time updates
TiDB
Open-source distributed SQL database with ACID transactions, HTAP, MySQL compatibility, and vector search
DuckDB
In-process SQL OLAP database for analytical queries with CLI, language clients, and direct CSV and Parquet reads
Directus
Wraps any SQL database in instant REST and GraphQL APIs, a no-code admin app, and auth
Qdrant
Vector database and search engine for semantic search with payload filtering, hybrid search, and distributed deployment