None of these are open-source, unfortunately.

Atlantis has an issue open for OpenTofu support [1]. This might be something to look out for.

[1] https://github.com/runatlantis/atlantis/issues/3741

None of these are a replacement of Terraform Cloud (recently rebranded to HCP Terraform). For example, when you create a PR, it could affect multiple workspaces. The new experimental version of TFC/TFE (I refuse to call it HCP!) implements Stacks, which is something like a workflow, and links one workspace output to other workspace inputs. None of the open-source solutions, including the paid Digger [0], support this - only the paid one, such as Spacelift [1] (which is the closest to TFC if you ask me). Having a monorepo of Terraform is a common design pattern, so, if I change an embedded module, it could trigger changes it many workspaces. As far as I know, Atlantis [2] can't really help in this case.

By the way, the reason I singled-out Spacelift is due to its quality, and the great Terraform provider it has. Scalr [3], for example, has a really low-quality Terraform provider. I extensively use the hashicorp/tfe provider to manage TFC itself.

[0]: https://digger.dev/

[1]: https://spacelift.io/

[2]: https://www.runatlantis.io/

[3]: https://www.scalr.com/

Hey Nikolay, thanks for sharing your experience with Scalr. When did you last evaluate the provider? afaik it covers everything, but perhaps we missed something?

Right before our TFC renewal, i.e. between September and October 2023. I will try to recollect the details and will share them with you.