Technical Due Diligence: Evaluating Codebases and Architecture for Acquisitions

The Hidden Factor in Deal Valuation

Merger and acquisition transactions in the technology sector reached $1.4 trillion globally in 2025, yet post-acquisition integrations fail to meet expected synergies in roughly 50% of deals according to post-merger audit data from major consultancy firms. While financial, legal, and commercial due diligence are standard, technical due diligence often receives compressed timelines and superficial coverage.

Technical due diligence is the systematic evaluation of an acquisition target's software assets: codebase quality, system architecture, infrastructure posture, security controls, engineering capability, and operational maturity. The findings directly impact valuation multiples, earn-out structure, and post-close integration cost.

The Four Pillars of Technical Due Diligence

1. Codebase Quality and Architecture

The codebase tells a story about engineering discipline, team velocity, and accumulated technical debt. A structured review examines:

• Repository structure and modularity. Monolithic repositories with no module boundaries indicate poor separation of concerns. A target with five well-defined microservices versus one with thirty loosely coupled services both can be fine—but the reasoning behind the architecture matters.
• Dependency hygiene. Count the number of direct and transitive dependencies, particularly abandoned or unmaintained packages. A project with more than 500 unresolved npm audit or pip-audit findings signals weak dependency governance.
• Test coverage and quality. Line coverage under 30% on critical paths is a red flag. More important than raw percentage is whether the tests actually guard against regressions—mutation testing scores provide better signal than line coverage numbers.

# Example: Dependency audit command output to review
# Run these during the codebase evaluation phase

# Count outdated production dependencies
npm outdated --production --long | wc -l
# 142 outdated packages identified

# Known vulnerabilities in production
npm audit --production --json | jq '.metadata.vulnerabilities.high'
# 18 high-severity vulnerabilities

# Test coverage report
npx jest --coverage --coverageReporters=json-summary
# Lines: 34.2% | Branches: 28.1% | Functions: 41.7%

2. Infrastructure and Cloud Posture

Review the target's infrastructure as code, deployment pipeline, and operational runbooks. Key evaluation areas:

• IaC maturity. Is infrastructure defined in Terraform, Pulumi, or CloudFormation, or manually provisioned through a web console? Manual infrastructure is a material risk; rebuilding from scratch may cost 8–12 engineering-weeks.
• CI/CD pipeline quality. Deployment frequency, change failure rate, and mean time to recovery are the DORA metrics that predict long-term engineering velocity. A team deploying once per month with a 25% failure rate will struggle to integrate into the acquirer's release cadence.
• Disaster recovery and backup validation. Does the target have documented DR procedures? When were backups last restored and tested? A gap here can turn a $50 million acquisition into a liability within the first quarter.

3. Security Posture

Security findings represent the highest-impact risk in technical due diligence. A comprehensive review should include:

• Third-party penetration test reports. Review the last two years of penetration test results. Recurring findings—especially in OWASP Top 10 categories like broken access control or injection flaws—indicate a systemic security culture problem rather than isolated bugs.
• Authentication and authorisation architecture. Multi-tenant SaaS applications must demonstrate robust tenant isolation. A misconfigured row-level security policy that allows cross-tenant data access is a deal-critical finding.
• Secrets management. Scan for hardcoded API keys, database credentials, or access tokens in source code repositories, container images, and CI logs. Tools like truffleHog and git-secrets can surface historical leaks even if recent commits are clean.

4. Engineering Organisation and Culture

The team building the software is as important as the software itself. Evaluate:

• Team composition and retention. High turnover in engineering—especially among senior staff—signals cultural or management problems that persist post-acquisition.
• Process maturity. Do teams use structured agile ceremonies, code review requirements, and change management processes? Ad-hoc engineering cultures that ship on hero effort are brittle and difficult to scale.
• Documentation norms. Architecture decision records, onboarding guides, runbooks, and API documentation are leading indicators of engineering rigour. Their absence is a predictor of integration friction.

| Risk Category | Low Risk | Moderate Risk | High Risk | |--------------|----------|--------------|-----------| | Code Quality | >60% coverage, modular | 30–60%, some tech debt | <30%, monolithic | | Infrastructure | Full IaC, automated CICD | Partial IaC, manual steps | Fully manual provisioning | | Security | 0 critical vulns, 3rd-party tested | 1–5 critical, remediation plan | >5 critical, no plan | | Team Health | <10% turnover, strong leads | 10–25% turnover, gaps | >25% turnover |

Translating Findings into Deal Terms

Technical due diligence findings should map directly to valuation adjustments. A target requiring six months of post-close remediation work to bring the architecture to acceptable standards implies a lower valuation or a longer earn-out period structured around remediation milestones.

Common financial adjustments based on technical findings include:

• Escrow holdbacks tied to security vulnerability remediation
• Earn-out multipliers conditioned on infrastructure migration completion
• Working capital adjustments for identified technical debt remediation costs

Quantify findings in engineering-weeks of effort. A $150,000 per month engineering team requiring eight weeks of remediation work represents $300,000 in post-close investment. That figure belongs in the deal negotiation, not the post-close surprise budget.

Making Technical Diligence a Deal Enabler

Strong technical due diligence does not kill deals—it enables informed decisions. Acquirers who invest in thorough technical assessment close transactions with confidence, know the true integration cost, and structure earn-outs that align incentives. In an environment where technology assets are core to deal thesis, skipping technical diligence is the highest-risk move of all.

Preparing for an acquisition or evaluating a target? Our technical due diligence practice delivers structured assessments across codebase quality, architecture, security, and team readiness. Explore our technical due diligence services to learn how we protect your transaction.