I am building a web application in which I intend to keep the source code private and proprietary. The web application would be used by end users for personal profit. I plan on using Turborepo (https://turbo.build/repo) by Vercel in order to speed up builds of my monorepo and using Terraform (https://www.terraform.io/) by Hashicorp for automating my infrastructure. Turbo is under the MPL 2.0 and Terraform is under the BSL. All of the other packages I intend to use are under the MIT or ISC license. I am confused about the constraints this puts on me. I am not going to make any changes to their source code at all, and don't even plan on distributing it, but both of these tools would be used in the build and deploy pipeline of my web app. Is there a difference between using these as build and development tools in my pipeline versus using them as packages in my own source code? Would this mean I need to reveal the source code or can I keep the project proprietary?
Is there a difference between using these as build and development tools in my pipeline versus using them as packages in my own source code?
Yes there is a difference. From a copyright perspective, your software is unlikely to be a derived work of your build tools.
As your software is not a derived work of your build tools, you can also license your software completely independently from the licenses of your build tools.