Build vs buy (and maintain)

Build vs buy was always a three-axis question, with maintain hidden inside both options. If you build, you’re maintaining your code. If you buy, you’re maintaining the integration into a vendor whose API will change, whose pricing will change, and whose roadmap will drift away from yours after a few years.

Buy mostly won because vendors amortize maintenance across thousands of customers. A small team can’t compete with a billing or auth vendor on that kind of math.

Maintenance was expensive mostly because of the reading and understanding involved, not the typing. Tracing bugs through someone else’s abstractions, decoding decisions made years ago by people who’ve since left. Vendors handled that for the parts of the stack you bought.

LLMs handle part of it now. A current model dropped into a codebase it has never seen can usually explain the architecture, follow a stack trace, suggest a fix that mostly works. Not perfect, but the distance between “code I wrote” and “code someone else wrote” is shrinking.

If maintaining unfamiliar code gets cheap, the build column gets more attractive. There’s a stronger version of this idea: ship software with a maintenance kit. Not a README in the usual sense. The actual context an LLM needs to keep the system running, like architecture decisions, invariants you depend on, failure modes you’ve already hit, the reasons specific shortcuts exist. The repo becomes its own operating manual for whoever (or whatever) maintains it next.

Open source already does some version of this, because the project only survives if strangers can read it. Most internal codebases don’t, because the people who wrote them are supposed to still be around three years later, and usually aren’t.

So the build vs buy question stops being about long-term staffing commitments. It becomes “did we leave the next maintainer enough context to keep this alive?”, and the next maintainer might not be a person.

The open question I keep coming back to: what does SaaS pricing look like when maintenance is close to free?