Is a platform that is "built on" Apache 2.0 open source the same as one licensed under Apache 2.0?
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Apache 2.0 and 'Built On' Are Not the Same License
Open catalog, open license: what is verifiable without a sales call.
Databricks and Snowflake both use the word open. Databricks names an Apache 2.0 project with a public repository, a spec, and clients anyone can fork. Snowflake names a product built on an open-source project it does not itself publish under an open-source license.
What "open" should mean here
Not a marketing adjective. A specific, checkable fact: is the catalog's own source published under an open-source license, or is it a proprietary product sitting on top of one. Those are different claims, and only one is verifiable by anyone, without an account team.
| Fact | Unity Catalog | Horizon Catalog |
|---|---|---|
| License of the catalog itself | Apache 2.0, spec, server, and clients published, LF AI & Data Sandbox project | Not published under an open-source license |
| Underlying open-source project it names | Is the open-source project | Built on Apache Polaris, a separate project |
| Where to verify without a sales call | unitycatalog.io, public GitHub repository | No public repository named for Horizon Catalog itself |
What shipped, and when
Open-source Unity Catalog is Apache 2.0 licensed, including an OpenAPI specification, server, and clients, and is an LF AI & Data Sandbox project. Anyone can read the license, fork the repository, and run the server without a Databricks account.
Snowflake describes Horizon Catalog as built on Apache Polaris and using Iceberg REST and Scan APIs. The open-source component Snowflake names is Apache Polaris, not Horizon Catalog itself. Snowflake Open Catalog is described as a managed service for Apache Polaris, a separate offering from Horizon Catalog.
Where Snowflake wins, stated plainly
Apache Polaris is real, is genuinely open source, and Snowflake's contribution to it is a real fact worth crediting. That fact describes Polaris, not Horizon Catalog, and the distinction is the entire point of this piece.
The limits of this argument
Hosted Unity Catalog on Databricks has proprietary surface area beyond the open-source project. The license claim applies to Unity Catalog OSS specifically, not to every feature of the hosted product.
The verdict
Built on an open-source project and published as one are different claims, and the scorecard needs both vendors held to the second, harder one.
Sources
[1] Databricks, Unity Catalog open source project. https://www.unitycatalog.io/
[2] Snowflake, Horizon product page. https://www.snowflake.com/en/product/features/horizon/
[3] Snowflake, "Open Catalog overview." https://docs.snowflake.com/en/user-guide/opencatalog/overview