> For the complete documentation index, see [llms.txt](https://documentation.immuta.com/2024.3/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://documentation.immuta.com/2024.3/secure-your-data/projects-and-purpose-based-access-control/masked-joins/enable-masked-joins.md). # Enable Masked Joins While masked joins are allowed, only project owners can add data sources to the project. Additionally, masked columns can only be joined if they are masked using hashing. In order to join mask columns across data sources, those data sources must be linked by a project. **Requirement**: You must own the project 1. [Create a project](/2024.3/secure-your-data/projects-and-purpose-based-access-control/projects-and-purpose-controls/how-to-guides/create-project-tutorial.md) or select an existing project. 2. Navigate to the **Overview** tab. 3. Click the **Allow Masked Joins toggle**. 4. Click **Confirm**. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://documentation.immuta.com/2024.3/secure-your-data/projects-and-purpose-based-access-control/masked-joins/enable-masked-joins.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.