How to Prepare Your Codebase for Technical Due Diligence

A technical due diligence review examines the codebase, infrastructure, security controls, and team practices behind a product. Prepare current documentation and evidence of known risks so reviewers can understand what exists, what needs work, and how the team plans to address it.

What Technical Due Diligence Covers

Before you prepare, you need to know what reviewers look for. A standard technical due diligence engagement covers:

• Architecture and system design — Is the system decomposed sensibly? Are there obvious single points of failure?
• Code quality and maintainability — Is the code readable, tested, and consistently structured?
• Technical debt — How much of the team's capacity is consumed by maintenance and firefighting?
• Security posture — Are there known vulnerabilities, exposed secrets, or missing controls?
• Infrastructure and deployment — How does the team ship? Is there CI/CD? Is infra defined as code?
• IP and licensing — Do you own your code? Are open-source licenses compatible with commercial use?
• Team capability — Can the existing team execute the post-deal roadmap without key-person risk?

Reviewers are not expecting perfection. They are assessing whether the risks are known, manageable, and priced into the deal correctly.

Step 1: Audit Your Repository Before Anyone Else Does

Run your own internal audit first. The goal is to identify and document issues before a third party finds them without context.

Start with automated scans:

• Run a static analysis tool (ESLint, SonarQube, Semgrep, or equivalents for your stack) and export the report.
• Run a dependency vulnerability scan (npm audit, snyk test, pip-audit, or similar).
• Scan for accidentally committed secrets using a tool like truffleHog or gitleaks.

For each category of finding, write a short paragraph explaining what it is, why it exists, and what the remediation plan looks like. Include an owner and target date so reviewers can assess the remediation plan.

Prioritize Critical and High Findings

You cannot fix everything before a review. Prioritize:

1. Any exposed credentials or secrets in version control history — rotate these immediately.
2. Critical and high-severity dependency vulnerabilities with known exploits.
3. Authentication or authorization logic that has never been reviewed externally.

Leave medium and low findings documented with planned remediation dates.

Step 2: Document What the Code Does

Document the critical paths and check that the instructions match the current system.

Write or update the following:

• A README.md in every service or repository that explains what the service does, how to run it locally, and how to deploy it.
• An architecture diagram showing how your services communicate, what databases they use, and what third-party integrations exist.
• A data flow diagram if you handle personally identifiable information (PII) or payment data.
• A runbook for your most common operational tasks (deployments, rollbacks, database migrations).

If your architecture has evolved significantly, document the current state — not the aspirational future state.

Step 3: Make Technical Debt Visible and Bounded

Create a simple technical debt register. A spreadsheet or a set of tagged GitHub issues works fine. For each item note:

• What the debt is (e.g., "authentication service does not support MFA")
• Why it was incurred (speed, team size, early pivot)
• What the estimated effort to remediate is
• Whether it blocks any post-deal initiative

Review the register with the engineering leads and identify which items affect the proposed roadmap.

Step 4: Clean Up Repository Hygiene

Check repository access, build status, and configuration before the review:

• Review branch access and protect the main branch; preserve history and evidence needed for the review.
• Make the change history understandable through release notes and pull request context; do not rewrite shared history to improve appearances.
• Confirm that your CI pipeline passes cleanly on the main branch.
• Remove any commented-out code blocks that are more than a few weeks old.
• Check that environment-specific configuration is stored outside the codebase (environment variables, secrets manager — not .env files checked in).

Step 5: Prepare for the Team Assessment

If the review includes interviews with engineering leads, prepare to explain:

• Why certain architectural decisions were made and what the trade-offs are.
• What the on-call and incident response process looks like.
• How new engineers get up to speed (onboarding documentation matters here).
• What the deployment frequency and rollback process are.

Support the discussion with examples from recent deployments, incidents, and architecture decisions.

Discuss technical due diligence preparation with LinkIT.