Technical Due Diligence: What Investors Actually Check Before Funding Your Startup

You have the traction. You have the pitch deck. Then an investor says the four words that make founders' hearts sink: "We'd like to do technical due diligence."

Most founders have never been through technical DD, so they treat it as a mystery. It is not. Technical due diligence is a structured review of your product's codebase, architecture, and technical team — and the investor's real question is always the same: what breaks and what do we own if this goes wrong?

This guide is the other side of the table. I have written about technical due diligence before building — the framework a founder uses to assess their own project and the people building it. This guide flips that perspective: what happens when the investor runs the same kind of review on you. Knowing what they check is the difference between walking into DD confident and watching a deal die over a codebase you never looked at.

Why Investors Do Technical Due Diligence

Investors are not looking for a reason to say no. They are looking for a reason to say yes without surprises. A successful DD is one that finds no fatal issues, not one that finds no issues at all — every early-stage product has rough edges, and investors know it.

What they are really assessing is risk:

• Build risk: can this team turn this codebase into the company the pitch deck describes?
• Ownership risk: does the startup actually own what it thinks it owns?
• Exit risk: can this be sold, acquired, or scaled without a technical landmine going off?

DD firms and technical consultants who run these reviews consistently look at the same short list of areas. Knowing the list lets you prepare for it instead of being caught flat-footed.

What Investors Actually Check

1. Architecture and Scalability

The first question is not "does it work?" — it is "can this grow?" Investors want to know whether the architecture supports the roadmap they are being pitched.

They will look at how the system is structured: whether there is a real separation of concerns, how the data model is designed, whether the app is a monolith or uses services, and how it will behave when users multiply by ten. They are not expecting a Google-scale system in a seed-stage startup. They are checking for signs that the architecture will force a rewrite at exactly the wrong time — a single database that will choke, a client-side app with no backend, no way to add the features the roadmap promises.

The signal they react to is simple: does the architecture make the roadmap easier or harder?

2. Code Quality and Test Coverage

Investors rarely read your code line by line — but a technical reviewer absolutely will. They look for whether the codebase is maintainable, whether it has automated tests, and whether a new engineer could get productive in it without a rewrite.

A rule of thumb used by technical DD practitioners like uxcontinuum: test coverage below roughly 30% is a red flag, because it means most of the app's behavior has no safety net. More important than the percentage is the critical path — the payment flow, the auth flow, the core algorithm. Investors want to see the business-critical code covered by tests, not just utility functions.

3. Security Posture

For any startup handling user data, security is a deal-breaker category. The reviewer checks how authentication and authorization work, how sensitive data is stored and encrypted, and how secrets and credentials are handled.

One of the fastest deal-killers in any DD: secrets committed to the repository. A hardcoded API key in a public GitHub repo is not a fixable annoyance — it is evidence of how the team handles risk, and it costs real money to remediate. The Black Duck 2025 OSSRA report found that a staggering 86% of audited codebases contained outdated or vulnerable components — meaning dependency hygiene is one of the most common, and most avoidable, findings in technical DD.

4. Dependencies and Licenses

Reviewers scan your dependency tree for two things: vulnerabilities and licensing risk.

Vulnerable packages are the low-hanging fruit of DD — tools like npm audit, pip-audit, or GitHub's Dependabot surface them in minutes. If an investor finds a critical CVE in a dependency you use in production, they will ask why it was not updated. Licensing matters just as much: if you have copied code that uses a restrictive license, or your product depends on something that conflicts with your business model, that is ownership risk.

5. Intellectual Property and Ownership

This is the most common reason a deal stalls. The investor's lawyer wants to confirm the startup owns what it is selling.

They check: who wrote the code (employees? contractors?), whether IP assignment agreements exist for every contributor, whether third-party code is licensed correctly, and whether the founder's prior employer could have a claim on the work. Startups built on an agency's codebase have burned deals here — if the agency holds the rights, the startup is building on borrowed land. This is exactly why the agency contract needs a clean IP clause, and why the pre-build due diligence framework checks ownership from day one.

6. Team and Key-Person Risk

Technical DD is as much about people as code. If the entire product lives in one person's head, the investor is funding a single point of failure.

The reviewer wants to know: who are the technical people, how much does the business depend on them, and what happens if they leave? Documentation matters here — a codebase with written architecture notes and onboarding docs is a team that can survive changes. A codebase that only its creator can understand is a hostage situation.

7. How Much of the Code Was Written by AI

A newer item that has joined the checklist. With AI-assisted development now standard, investors are no longer asking whether you use AI tools — they want to understand how. Unexamined, AI-generated code with no review, no tests, and no one who understands it is a maintenance liability. Code written with AI-assisted review and test coverage is a productivity win. The difference is process, and DD will notice the difference.

How to Prepare for Technical DD as a Founder

You do not need a flawless codebase — you need a defensible one. Here is what moves the needle before the review starts.

• Run the vulnerability scans yourself first. npm audit, pip-audit, Dependabot, Snyk — whatever your stack uses. Fix the criticals before an investor finds them. The finding is cheaper to fix now than in the middle of a term sheet.
• Write down the architecture. Even a two-page document explaining the system, the data model, and the key decisions makes an enormous difference. Investors are not judging the document's length; they are judging whether the team understands its own system.
• Check the IP paperwork. IP assignment for every contributor, contractor agreements, and clean licensing. If this is messy, fix it before DD, not after the deal is on the table.
• Remove secrets from the repo — and from git history. git log still shows deleted secrets. Tools like git-filter-repo can clean history, but the safer move is rotating the exposed credentials entirely.
• Cover the critical path with tests. You do not need 90% coverage. You need the payment flow, auth, and core algorithm to have tests.
• Document how the code was built. A short note on your AI-assisted development workflow — review, testing, human oversight — turns a liability into a positive signal.

What Is a Deal-Killer vs. What Is Negotiable

Not every finding kills a deal. Understanding the difference keeps you calm when the DD report comes back.

Deal-killers (fix or fail):

• No IP ownership — the code belongs to someone else
• Secrets and credentials exposed in public repos or live systems
• Critical vulnerabilities in the dependency tree with no plan
• No way to scale the system to support the roadmap

Fixable findings (negotiable, common in every seed deal):

• Low test coverage
• Documentation gaps
• Messy code in non-critical areas
• A hard-to-maintain section that will be rewritten anyway

Investors fund messy startups every day. They do not fund startups that don't own their own software or that leave the keys to the kingdom in a public repo.

Get the Checklist

I have packaged all of this into a free, practical Technical Due Diligence Checklist — a fill-in-the-blank readiness review covering architecture, code quality, security, dependencies, IP, and team risk. Run it before you take investor calls and you will walk into DD knowing exactly where you stand.

And if the checklist surfaces a mess you cannot untangle alone, that is exactly the situation I work in as a technical partner — auditing a codebase, cleaning up ownership and security issues, and getting a startup to the point where technical DD stops being a fear and starts being a formality.

FAQ

What is technical due diligence?

Technical due diligence is the process where an investor — usually with a technical consultant — reviews a startup's codebase, architecture, security, intellectual property, and team to assess technical risk before funding. The goal is to confirm the startup owns its software and can build the roadmap it pitches.

How long does technical due diligence take?

A typical technical DD review takes one to three weeks, depending on the codebase size and the depth of the review. Founders can shorten it dramatically by having architecture documentation, clean IP paperwork, and fixed dependency vulnerabilities ready in advance.

How much does technical due diligence cost?

For startups, the cost is usually borne by the investor and ranges from a few thousand to tens of thousands of dollars depending on the scope and firm. Founders rarely pay for it directly — but they pay in deal risk if they are unprepared.

What do investors look for in technical due diligence?

Seven areas: architecture and scalability, code quality and test coverage, security posture, dependencies and licenses, intellectual property ownership, team and key-person risk, and how AI-generated code is handled. The unifying question is what could break — and what the startup actually owns.

What can kill a deal in technical due diligence?

Fatal findings are almost always about ownership and exposure: the startup does not own its code, secrets are committed to public repos, critical vulnerabilities are unaddressed, or the architecture cannot support the pitched roadmap. Low test coverage and documentation gaps are common but rarely fatal.

How do I prepare for technical due diligence as a startup?

Run the security scans yourself and fix criticals, write a short architecture document, verify IP assignment for all contributors, remove and rotate any exposed secrets, cover the critical path with tests, and document your development process. The technical DD checklist walks through all of it.

Related Reading

• Technical Due Diligence Before Building — the pre-build framework for assessing a project and its team
• Startup Tech Stack 2026 — architecture decisions that hold up in DD
• SaaS Architecture Guide — what scalable SaaS architecture actually looks like
• When to Hire a Technical Partner — who prepares your technical package when you are too busy raising to do it
• SaaS Development Cost 2026 — what the roadmap you are pitching actually costs