Who Should Do Technical Due Diligence on a Code Acquisition?

The right answer to who should do your technical due diligence is usually a mix: a neutral tooling pass, a third-party reviewer for independence, and your own engineers for fit. What you should never do is let the people who want the deal to close be the only ones judging the code. That is the conflict that sinks deals after signing. The champion inside your company, the one whose bonus or reputation rides on the acquisition, is exactly the wrong person to also be the one deciding the codebase is fine. Separate the enthusiasm from the assessment.

The conflict of interest nobody names

Every acquisition has a champion, an executive or team lead who sourced it, pushed for it, and now wants it done. That energy is useful, right up until the champion is also the technical reviewer. Then every finding gets minimized, because a serious problem threatens the thing they have been fighting for. The review becomes a search for reasons to proceed, not an honest assessment.

This is not about bad faith. It is about incentives, and incentives bend judgment quietly. The fix is structural: whoever owns the outcome of the deal should not be the sole voice on whether the code is acceptable. Build the review so at least one assessor has no stake in the answer.

Your own engineers: essential for fit, wrong for independence

Your engineers know what you are going to build on this code, which makes them irreplaceable for judging fit. They can look at the architecture and say whether it supports your roadmap or fights it, a judgment that an audit alone cannot make because it does not know your plans. Nobody outside your company can answer the fit question as well.

But they have two limits. They may be too busy to do a real review while shipping their own work, so the audit gets rushed. And if they will inherit and operate the code, they can be biased in either direction, either talking themselves into it because they are excited, or trashing it because they would rather build their own. Use them for fit, and pair them with someone whose judgment on quality is not colored by having to live with the result.

The third party: independence you cannot manufacture internally

A neutral outside reviewer has one thing your team cannot have: no stake in the outcome. They get paid the same whether the deal closes or dies, so their findings are not bent by hope or fear. That independence is the whole point, and it is why serious acquisitions bring in an outside technical review even when they have strong internal engineers.

The third party also brings pattern memory, because they have audited many codebases and know what the common rot looks like, where the git history red flags hide, and how to run the scan-then-review sequence efficiently under a deal clock. Their weakness mirrors your team's strength: they do not know your roadmap, so they cannot judge fit. Which is exactly why you want both.

Tooling first, as the neutral baseline

Before either set of humans, run the tooling, because a scan has no opinion about the deal. A repo intelligence pass produces the coupling map, hotspots, ownership concentration, and dependency health as raw facts that no champion can spin, and it gives both the third party and your engineers the same starting map. Facts everyone shares are harder to argue away than impressions, and the tooling supplies the facts.

The scan also makes the human hours efficient, which matters when your engineers are borrowed from real work and the third party is billing by the day. Point them at what the repo due diligence checklist says matters, aimed by the scan, and you get depth where it counts instead of a random walk through the files.

The setup I would insist on

For a deal that matters: tooling produces the neutral map, a third party does the independent quality assessment with no stake in closing, and your own engineers judge fit against the roadmap. Three views, and critically, the person who wants the deal is not the only one grading the code. If someone pushes to skip the third party because the internal team already looked, ask who on that team gets hurt if the deal falls through. That person's optimism is not diligence, and treating it as diligence is how buyers end up owning problems they were told did not exist.