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It's a split decision.
Choose DuckDB for analytical SQL inside an application, local data work, or pipelines that read and write CSV, JSON, Parquet, and Iceberg. Its APIs cover Python, Go, Java, Node.js, and Rust. Choose PostgreSQL when your application needs a self-hosted object-relational database server with official documentation and community resources. Both are free and open source, but they have different deployment models: DuckDB runs in-process or on servers, while PostgreSQL is a database server your team operates.
01Side by side
| DuckDB | PostgreSQL | |
|---|---|---|
| Pricing model | Free MIT-licensed project; no paid plans published | Free open-source software; no paid plans |
| Free tier | Free for personal and commercial use | Free of charge for commercial and noncommercial users |
| Open source and licence | Open source under the MIT License | Open source under the PostgreSQL License |
| Self-hosting | Self-host on devices or servers | Self-host; teams supply hosting and operations |
| API and SDKs | Native APIs for Python, Go, Java, Node.js, Rust | Homepage does not enumerate language APIs or SDKs |
| CLI and docs | CLI plus language-specific installation options | Official installation and usage documentation |
| Integrations | Lists cloud, database, language, and format integrations | Homepage lists no specific integrations |
| Deployment model | In-process database; also deployable on servers | Open-source object-relational database server |
DuckDB Choose DuckDB if
- Choose DuckDB if you need in-process analytical SQL.
- Choose DuckDB if your data work uses CSV, JSON, Parquet, or Iceberg.
- Choose DuckDB if you want listed APIs for Python, Go, Java, Node.js, or Rust.
PostgreSQL Choose PostgreSQL if
- Choose PostgreSQL if your application needs a self-hosted database server.
- Choose PostgreSQL if you want an object-relational database with over 35 years of active development.
- Choose PostgreSQL if official documentation and community resources are central to your team.
02Pricing at real usage
DuckDB is free under the MIT License for personal and commercial use; PostgreSQL is free under the OSI-approved PostgreSQL License. Neither publishes a paid plan, so there is no software bill that scales by seats, queries, storage, or compute. DuckDB lists no usage limits; PostgreSQL lists no published seat or usage limits. Those terms do not remove infrastructure costs. With DuckDB embedded, your application’s host supplies CPU, memory, and storage; running it on servers still leaves you responsible for those resources. With PostgreSQL self-hosted, your team supplies server capacity and handles operations. Managed hosting or cloud infrastructure for either database adds a separate provider bill. Budget for hosting, storage, backups, and operational work, not a database licence charge.
03API, SDKs and integration
DuckDB runs in-process and offers native APIs for Python, Go, Java, Node.js, and Rust, alongside a CLI and ODBC. The homepage also lists integrations with AWS, Azure, Google Cloud, SQLite, MySQL, and PostgreSQL. For data access, DuckDB reads and writes CSV, JSON, Parquet, and Iceberg, locally or in object storage. Its Quack protocol supports remote access between DuckDB instances, with computations possible on the client side. PostgreSQL is an object-relational database server. Its homepage directs developers to official documentation for installation and use, and to community resources; it does not enumerate language SDKs or integrations. The architectural choice is the key integration difference: embed DuckDB in an application for analytical work, or connect an application to a PostgreSQL server. Check the documentation for the clients and deployment details your stack requires.
04Open source, self-hosting and lock-in
Both databases are open source and self-hostable. DuckDB uses the MIT License and runs in-process or on devices and servers. PostgreSQL uses the OSI-approved PostgreSQL License; teams supplying their own hosting also take on its operational work. DuckDB can read and write CSV, JSON, Parquet, and Iceberg, which gives teams options for moving data through supported formats. That does not guarantee that queries, types, or application behavior transfer unchanged between database systems. DuckDB’s SQL is PostgreSQL-inspired, but the homepage does not claim full compatibility. PostgreSQL’s homepage does not describe a data-export or migration workflow. Before choosing either, plan how your application will move data and validate SQL behavior if you later switch engines. Both are open source, but the work to change systems depends on how your code uses each database.
Questions people ask
Is DuckDB a replacement for PostgreSQL?
Not by default. DuckDB is an analytical database that can run inside an application; PostgreSQL is an object-relational database server. Pick DuckDB for embedded analytical SQL and file-based data work, and PostgreSQL when your application is built around a database server.
Can DuckDB work with PostgreSQL?
DuckDB’s homepage lists PostgreSQL among its database integrations. It also lists the Quack protocol for remote access between DuckDB instances. The homepage does not specify the exact PostgreSQL integration workflow, so check DuckDB’s documentation for the connection and data operations your application needs.
Which database is faster?
The published product pages do not provide a direct DuckDB-versus-PostgreSQL benchmark, so we can’t name a general performance winner. DuckDB is positioned for analytical SQL, while PostgreSQL is an object-relational database. Compare them with your own queries, data sizes, and deployment pattern before committing.
Do DuckDB and PostgreSQL charge per query or user?
Neither publishes a paid database plan or usage-based software pricing. DuckDB is free for personal and commercial use under the MIT License. PostgreSQL is free under the PostgreSQL License. Hosting and infrastructure can still cost money, especially when your team runs the database on servers.