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TeamCity does not provide out of the box support for HTTPS access (see TW-12976) and it is recommended to setup a reverse proxy like Nginx or Apache in front of TeamCity which would handle HTTPS and use HTTP TeamCity server port as the upstream. HTTPS-related configuration of the proxy is not specific for TeamCity and is generic as for any Web application. Make sure to configure the reverse proxy per our recommendations below.
For small servers you can set up HTTPS via the internal Tomcat means, but this is not recommended as it can significantly increase CPU load.
For configuring clients to access TeamCity server via HTTPS while using self-signed certificate, check related instructions.
Configure TeamCity to Use Proxy Server for Outgoing Connections
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