> ## Documentation Index
> Fetch the complete documentation index at: https://docs.abbyy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Database server

> Choose a database engine for the ABBYY FlexiCapture Application Server. SQL Server, Azure, Oracle, and PostgreSQL are supported; MS SQL needs Mixed Mode.

The Application Server requires Microsoft SQL Server, Azure server, Oracle, or PostgreSQL for its operation (for a list of supported versions, see the [System requirements for ABBYY FlexiCapture Distributed](/flexi-capture/admin-guide/ds-requirements) section). Mixed Mode must be enabled in Microsoft SQL Server ("SQL Server and Windows authentication").

<Note>
  The ABBYY FlexiCapture setup disk includes Microsoft SQL Server 2019 Express, which can be used only for demonstration purposes.
</Note>