How to Pass a Technical Due Diligence Without Rewriting Your Stack

A founder called me in a panic last quarter. Their Series A was contingent on passing a technical due diligence, and the investor's assessor had sent over a 60-item checklist. The founder had two weeks. Their codebase was a typical seed-stage product — functional, shipping, and messy in the ways all early codebases are. They were convinced they needed a rewrite.

They did not need a rewrite. They needed two weeks of focused preparation. We prioritized the items that assessors actually care about, fixed the things that were fixable in the timeline, documented the things that were not, and framed the technical debt as a conscious product of shipping speed. They passed. The investors funded.

This is the prep guide I have used across a dozen DD preparations. The goal is not to pretend your codebase is perfect. The goal is to demonstrate that your technical team is competent, aware of the tradeoffs they have made, and capable of scaling.

What assessors actually look for

I do technical due diligence for investors (I wrote about the full framework in inside a technical due diligence), so I know what the other side of the table cares about. It is not what most founders expect.

They are not looking for perfect code. Every seed-stage codebase has rough edges. Assessors know this. What they are looking for is whether the team knows where the rough edges are and has a plan to address them.

They are looking for engineering competence. Can the team ship reliably? Is there CI/CD? Are there tests? Is the deployment process documented? These are proxies for whether the team can execute at the next stage.

They are looking for scaling risks. Is there anything in the architecture that will break at 10x the current load? Is the database schema sane? Are there single points of failure? The assessor is trying to estimate the cost of scaling, not the quality of the current code.

They are looking for security basics. Not SOC 2 compliance at seed stage — just the basics. Are secrets stored securely? Is authentication implemented correctly? Is there logging? Are dependencies up to date?

They are looking for IP risk. Is the code original? Are open-source licenses compatible with the business model? Is there any AI-generated code with unclear provenance?

The two-week prep checklist

If you have two weeks before a DD, here is where to spend the time:

Week 1: Documentation and hygiene

Write a technical architecture document. One to two pages. What the system does, how it is structured, what the major components are, what the data flow looks like. Include a simple diagram. This document should exist regardless of DD — it is useful for onboarding — but if it does not exist, write it now.

Write a known issues and tech debt document. List the things you know are wrong. For each one, note the impact (low/medium/high), the effort to fix, and when you plan to address it. This document is the single most important artifact in a DD. It says: "we know what the problems are, we made conscious tradeoffs, and we have a plan."

Ensure README files are current. Every major directory should have a brief explanation of what it contains. The assessor will browse the repo, and clear READMEs reduce the number of "what does this do?" questions.

Clean up the Git history. This does not mean rewriting history. It means ensuring the default branch is the main branch, stale branches are deleted, and recent commits have clear messages. The assessor will look at the commit history for patterns.

Week 2: Technical fixes

Run npm audit or equivalent and fix critical vulnerabilities. Do not fix everything — fix the criticals and high-severity issues. Document the remaining ones with a timeline.

Ensure CI runs on every PR. If you do not have CI, set it up. GitHub Actions with a basic test suite is a one-day effort. A codebase without CI is the most common red flag in a DD.

Add basic test coverage for the critical paths. You do not need 80% coverage. You need tests for authentication, payment processing, and whatever your core business logic is. Even 10 well-placed integration tests are better than no tests.

Review your secrets management. No hardcoded API keys in the code. Secrets in environment variables or a secrets manager. If any secrets are in the Git history, rotate them and note that you have done so.

Verify your backup strategy. Can you restore the database from a backup? Have you tested it? If not, test it now and document the process.

Review your deployment process. Can you describe it? Is it repeatable? Can another engineer deploy without the founder present? Write it down if it is not documented.

How to frame technical debt

The biggest mistake founders make in a DD is being defensive about technical debt. Do not hide it. Do not downplay it. Frame it.

The framing: "We chose shipping speed over code quality in these specific areas because we were validating product-market fit. Here is what we would improve in the next quarter, here is the estimated effort, and here is why we chose to defer it."

This framing works because it demonstrates three things assessors value: awareness (you know the problems), judgment (you made conscious tradeoffs), and planning (you have a path forward).

The framing that does not work: "We do not have much technical debt." Every seed-stage codebase has technical debt. Claiming otherwise signals either that the team does not recognize it or that they are hiding it. Both are red flags.

The questions you will get asked

Based on the dozens of DDs I have conducted and prepared for, these are the questions that come up most:

"Walk me through the architecture." Have the diagram ready. Explain the major components, the data flow, and the external dependencies. Keep it concise — the assessor wants to understand the system, not hear a lecture.

"What is your test strategy?" Describe what is tested, how it is tested, and what the coverage looks like. Be honest about gaps. "We have integration tests for auth and billing, unit tests for the business logic, and we know we need more coverage on the data pipeline."

"How do you deploy?" Describe the process from merged PR to production. CI, staging, production. Manual steps if any. Rollback process.

"What keeps you up at night?" This is the tech debt question in disguise. Answer it with your known issues document. Name the top three things you would fix if you had a free month.

"How would this scale to 10x?" Walk through the scaling path. What would need to change? What would stay the same? The assessor is not expecting you to have already built for 10x. They are expecting you to have thought about it.

"What is your security posture?" Authentication, authorization, secrets management, logging, dependency management. The basics from the startup security baseline.

What to stop worrying about

Code style inconsistencies. Nobody fails a DD because of inconsistent naming conventions.

Old patterns in old code. If the team has improved their practices and new code is better, the assessor will notice the trend and view it positively.

Missing documentation for every function. Assessors read code, not JSDoc comments. Clear code is better than commented code.

Not using the latest framework version. Being on Next.js 14 instead of 15 is not a risk. Being on a deprecated, unsupported framework is.

Imperfect test coverage. 30% coverage with well-placed tests is better than 80% coverage with trivial tests that do not catch real bugs.

Counterpoint: when a rewrite is the right answer

Rarely, the DD preparation reveals something fundamental. The architecture cannot scale without a rewrite. The security model is fundamentally broken. The codebase is built on a deprecated platform with no migration path. In these cases, the honest answer is better than a cover-up. Tell the investor: "Here is the problem, here is our rewrite plan, here is the timeline and cost." Investors fund teams, not codebases, and a team that can articulate a clear rewrite plan is a team worth funding.

Your next step

If you have a DD coming up, start with the known issues document this week. List every piece of technical debt you are aware of, categorize by impact, and draft a one-sentence plan for each. That single document will answer half the assessor's questions and set the tone for the entire review.

Where I come in

I do DD preparation from both sides — I conduct DDs for investors, and I prepare startups for DDs. The preparation engagement is typically 1–2 weeks of focused work: architecture documentation, risk identification, targeted fixes, and a practice run of the assessor's likely questions. Book a call if you have a DD coming up and want to walk in prepared.