Should you build or buy software? This Wall Street firm has a new tool to decide.

The build-versus-buy debate around business software has a new calculator.

Last year, I wrote about how AI coding tools were making it easier for companies to create their own internal apps instead of paying an outside software provider.

That shift raised a tempting question: Why keep buying expensive software when employees can now vibe code a custom version themselves?

The enterprising analysts at RBC Capital Markets recently built an interactive tool to test that idea.

Companies and investors can plug in the cost of a software subscription, then compare it with the full cost of building and running an in-house alternative.

The tool goes beyond the initial coding bill.

It also includes maintenance, security risks, repairs, and the cost of employees using a tool that may be less reliable or capable.

RBC’s conclusion is sobering: Building your own version of business software is usually more expensive than buying it.

The math can work for simpler, less important tools, but rarely for core systems such as payroll, customer records, or office software.

The biggest hidden cost may be talent.

Even when a custom app is possible, companies must ask whether their best AI workers should rebuild existing software or create something genuinely new.

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Reach out to me via email at abarr@businessinsider.com.