Build vs buy: should you build it with AI or keep paying for it?

AI makes it easy to build your own version of the software you pay for. Answer 10 quick questions about one tool and get a straight answer: build it, use open source, or keep paying.

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Run this check inside Claude

A free Claude skill that asks the same ten questions, plots your answer on the same map, looks up real open-source and paid options for your job, and writes a decision brief you can forward. It can also sort your team's whole stack.

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How to make the build vs buy call

Most teams used to buy by default, because building took a team and months. AI coding agents made a working first version cheap, but someone still has to host it, fix it, update it and support the people using it. That ongoing cost is what the quiz weighs.

Build

Make your own version, often with an AI coding agent. It's worth it when you'd use it every day and someone owns the upkeep.

Borrow

Use a maintained open-source project. Run it yourself, or pay a host to run it for you.

Buy

Pay for a service that already does the job, and let them handle reliability, updates and support.

Five checks before you build anything

Make the custom benefit countBuild because a tool keeps getting in your way. Saving a subscription fee is rarely enough on its own.
Test the whole jobRun one real piece of work through it end to end: make it, change it, reopen it, export it, then restore a backup.
Check what already existsA free plan, an open-source project or a managed service may already do this.
Look past the interfaceA copy of the interface doesn't come with the tool's users, content library, edge-case handling or integrations.
Name who maintains itBefore anyone builds, name the person who'll fix it when it breaks. If there's nobody, pay a vendor to own it.

How the quiz decides

Payoff adds up how much better your version would be, how often you'd use it, and whether it's part of your edge (0–6).

Burden adds up the size of the job, the cost of it breaking, what it connects to, and how sensitive the data is (0–8).

Three answers override both scores. If you haven't checked what exists, check first. If a paid tool or an open-source project already fits, use it. If nobody will maintain it, pay for it, unless it's your edge and you'd use it daily, when building it with a partner fits. The scores show the reasoning so you can argue with it. They don't estimate savings.

Build vs buy for AI agents

Buying from specialized vendors and building partnerships succeeds about 67% of the time. Internal builds succeed about a third as often. MIT NANDA, The GenAI Divide (2025), as reported by Fortune

A working agent demo only takes an afternoon, so it's easy to start building before anyone asks whether you should. Build where the workflow is part of how you compete, keep the first version narrow, and name the owner before launch.

What we learned testing it

We built this quiz while making an episode about rebuilding apps with AI, then ran our own projects through it.

Build

A custom podcast link page

The job was small and stable, the custom design mattered to us, and we already had hosting, so building it was worth it and saved us a paid plan. Change the upkeep answer to “nobody” and the quiz says to pay instead.

Check first

A Canva-style design editor

We built one with Codex and an open-source portrait model. It passed our tests, including one that caught a real font-export bug. We haven't finished comparing it with existing tools, so the quiz says to check those first.

Borrow

An open-source photo editor

PhotoCraft, a community project, handled our editable-text test, but one complex Photoshop file came out visibly different. If you borrow, test it on your own files.

Buy

A blog CMS

Running a publishing system isn't where we want our time to go. WordPress is open source, but someone still has to host it, update it and keep it secure. For that job, paying for a managed plan wins.