Whether you are an investor writing a check, a founder acquiring a small product, or a CEO who inherited an engineering team you did not build, technical due diligence answers one question: can this team and this codebase actually deliver what the story says they can? Most non-technical leaders skip it or outsource it entirely, and then discover the truth the expensive way. You do not need to be an engineer to run a good diligence process. You need to know what to look at and which answers should worry you.
Key Takeaways
- Diligence covers three things: the code, the team, and the process that connects them.
- You are looking for risk, not perfection. Every real codebase has debt.
- The worst findings are usually about people and process, not lines of code.
- Bring in a trusted senior engineer to read the parts you cannot, and tell them what to flag.
The Three Things You Are Assessing
Good technical due diligence looks at the codebase, the team, and the process, because a weakness in any one of them undermines the other two. The code question is not "is it perfect" but "how much risk is buried here": security holes, fragile architecture, a dependency on one irreplaceable person, or debt so deep that every new feature costs triple. The team question is whether the people who built it understand it and will stay. The process question is whether they can ship reliably, or whether releases are heroics. A clean codebase with a team about to quit is still a bad bet.
What to Actually Look At
You can gather most of the signal with a short list of concrete asks, even without reading the code yourself.
| Area | Ask for | Red flag |
|---|---|---|
| Code health | A walkthrough of the architecture | Nobody can explain it clearly |
| Bus factor | Who is the only person who knows X | Several critical systems, one owner |
| Security | How they handle secrets, access, and data | No answer, or "we should do that" |
| Delivery | How a change gets to production | Manual, slow, and scary |
| Debt | What they would fix with a free month | No awareness of their own debt |
The most revealing question is the last one. A team that can name its own technical debt clearly is in control of it. A team that says everything is fine either does not know their system or is not telling you.
A Concrete Version
An operator acquiring a small SaaS product almost skipped the technical review because the demo was smooth and the revenue was real. On a two-hour walkthrough, a trusted senior engineer asked who could deploy the app, and the answer was one contractor who had left three months earlier. The deploy process lived in his head, the last release had been done by copying files to a server by hand, and the entire payment flow had no tests. The revenue was real and the product was one bad deploy from an outage nobody could fix. That single question changed the price and the plan, and it cost two hours to ask.
The Honest Counterpoint
Diligence can tip into theater, where you generate a hundred-page report full of findings that do not matter and miss the two that do. Every real codebase has debt, ugly corners, and things the team would do differently. The job is to find the risks that would actually break the thesis, not to fail a team for being imperfect. Those risks are the single point of failure, the security hole, the team that is about to walk, and the process that cannot ship. Grade on the risks that matter, and do not confuse a long list of nits with a real assessment.
Frequently Asked Questions
Can I do this if I am not technical?
Partly. You can run the interviews and ask the structured questions yourself, but bring in a trusted senior engineer to read the code and judge the architecture. Tell them exactly what to flag.
What is the single most useful question?
Ask the team what they would fix with a free month. The clarity of the answer tells you whether they understand and control their own technical debt.
What findings should actually kill a deal?
The ones that break the thesis: a critical system only one departed person understands, an unaddressed security or data risk, or a team signaling they will leave. Nits and normal debt should not.
The Bottom Line
Technical due diligence is about finding the risks that matter, across the code, the team, and the process, not about grading a codebase for perfection. Ask the structured questions yourself, bring a trusted senior engineer for the parts you cannot read, and focus on what would actually break the plan. For related reads, see how to audit code a contractor wrote and how to verify a senior engineer. See available engineers.
Roberto Espinoza is CEO of Ruzora, which helps US startups hire pre-vetted senior LATAM engineers, with a vetted shortlist in 72 hours. See available engineers.
