Technical Due Diligence: The Complete Guide

What is technical due diligence?

Technical due diligence is a systematic evaluation of a company's technology, codebase, architecture and engineering practices, used by investors and acquirers to assess technical risk before committing capital. It normally covers security, code quality and architecture, technical debt, testing and CI/CD, and team practices, and it typically runs after a term sheet and before close.

What do investors actually check?

Investors examine seven things: exposed secrets and credentials, dependency vulnerabilities, architecture and scalability, test coverage and CI/CD, a technical debt inventory, security practices, and documentation and onboarding. The finding that damages a deal is rarely messy code — it is a problem the founders did not know they had.

What makes a deal fall apart?

Deals are repriced or abandoned over discoveries, not imperfections. Exposed production credentials, a licence obligation that threatens the product's IP position, a dependency surface nobody can account for, or a codebase only one departing person understands — each of these turns a valuation conversation into a risk conversation.

How to prepare before diligence starts

Audit yourself first. Running your own review and disclosing known issues alongside a prioritized plan builds credibility and protects the valuation; letting an investor's analyst find the same issues mid-process is what damages a deal. Preparation also means having an SBOM, a dependency inventory and current documentation ready before they are requested.

Reading the report you get back

A diligence report is written for decisions, not for engineers. Work from the executive summary to the prioritized fix plan, and treat severity ratings as a queue rather than a verdict. A list of problems is only useful once it has an order, an owner and a cost attached to each item.

Frequently asked questions

When does technical due diligence happen?

Usually after a term sheet is signed and before the deal closes. It is standard from Series A onward, in most acquisitions, and whenever a buyer is taking a majority stake in a technology company. Earlier-stage rounds sometimes skip it, though that is changing as more products are built with AI assistance.

Can you fail technical due diligence?

Yes. A severe enough finding — a serious unaddressed security exposure, a licence problem affecting the core product, or a codebase that would need rebuilding to scale — can end a deal. More often it does not kill the deal outright but reduces the valuation or adds protective terms.

Who performs technical due diligence?

Either the investor's in-house technical team, a third-party firm they engage, or increasingly an automated assessment that the company runs on itself and shares. Many processes now combine them: an automated scan establishes the baseline, and human review focuses on what it flags.

What if my code is messy but works?

That is normal for an early-stage company and rarely fatal on its own. What matters is demonstrated awareness: showing you know where the weak points are, what they would cost to address, and why you deprioritised them is a stronger position than a codebase that looks tidy and hides surprises.

Audit your own codebase

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