Minimum required tools for a fully functional CI/CD

At work we have tfs 2015 update 3 and we develop in .net c#. Today we decided to explore what's possible for us to achieve a complete (also on production) automated testing and deployment pipeline and with possibility to rollback versions. We prefer to stay on-premise. We have following environments: dev, uat, release.

A colleague proposed Octopus Deploy. But I'm asking myself if this product is really necessary for CI/CD? Can't we just keep using Microsoft products? What brings Octopus Deploy on top of TFS or Azure DevOps server?

Other questions I have:

• Can I get advice about what the most used tools are today?
• Are there free alternatives for enterprise usage?
• Can we achieve CI/CD with only TFS (or the newest name: Azure DevOps server).
• Do we have to upgrade to Azure DevOps server?

Some other necessities are that we should have a solution with minimal expenses. In other words, it must be as cheap as possible.

Thanks for any input.

Minimum required tools for a fully functional CI/CD Click here