Fractional CTO Due Diligence: Evidence to Request Before a Software Acquisition

A software business can present a polished product while leaving important operating questions unanswered. Can another team deploy it? Are the critical components maintained? What happens when its most experienced engineer leaves? Which claims have been demonstrated and which are still assumptions?

A fractional CTO can help a buyer structure technical due diligence and translate the findings into operational questions. The assignment needs a defined scope and access to evidence. A short conversation with the seller's engineering lead is useful context, but it is not a substitute for examining the systems and processes that support the product.

This article is a scoping framework for technical review, not transaction, valuation, or legal advice. The review should support the buyer's qualified legal, financial, and specialist advisers rather than replace them. For background on the role, see what a fractional CTO does.

Define the decision and the limits of access

Begin with the reason for the acquisition. A buyer seeking a standalone product needs a different assessment from one planning to integrate the software into an existing platform. Record the assumptions that matter: service continuity, integration effort, delivery capacity, operating costs, or the ability to maintain the code after a handover.

Define what the reviewer may inspect and what is outside the assignment. Agree read-only access where appropriate, confidentiality arrangements, and how sensitive data will be minimized. A due-diligence mandate should not silently authorize intrusive production testing or changes to the seller's systems.

Write the limitations into the final report. A conclusion based on selected documents and interviews has a different evidential basis from one supported by repository access, deployment observation, and operational records. The reader should not have to infer that distinction.

Build an evidence request around six areas

Request representative evidence rather than every file the seller possesses. Start with the components that support the core customer experience and expand where findings justify it. This keeps the review connected to the transaction's actual technical questions.

Examine architecture through a real customer journey

Ask the engineering team to walk through a core workflow from the customer's action to the systems that process and store the result. Identify third-party services, background jobs, integrations, and manual steps. A diagram becomes useful when the team can connect it to the running product.

Look for boundaries that affect maintainability. Which changes require coordinated releases? Which data is duplicated? Where do integrations rely on an undocumented format or one employee's knowledge? Complexity is not inherently a defect; the question is whether the team understands and can operate it.

Avoid using a technology's age as a verdict. An older stack with maintained dependencies and a repeatable release process may present fewer immediate operating problems than a fashionable stack with unclear ownership. Findings should explain the consequence for the intended operating model.

Observe how a change reaches production

Choose a representative recent change and trace it through review, tests, build, and release. Ask what evidence shows that the deployed version matches the reviewed code. Examine how configuration is managed and how the team would reverse a failed release.

Where the parties permit it, observe a demonstration in a suitable non-production environment. The objective is to understand the process, not to surprise the seller with a live experiment. Record whether the demonstration used the ordinary procedure or a specially prepared path.

Then examine the exceptions. Emergency changes, manual database updates, and skipped checks may reveal more than the ideal workflow. Ask how these events are recorded and reconciled. A team that can explain a controlled exception provides a stronger basis for assessment than one that claims exceptions never happen.

Review secure development as a process

NIST's Secure Software Development Framework, SP 800-218, provides a vocabulary for examining how software is prepared, protected, produced, and maintained in response to vulnerabilities. Use the practices relevant to the assignment as prompts for evidence, not as a claim that completing a checklist certifies the target company.

Ask who owns security decisions, how access changes when people leave, how dependencies are tracked, and how reported weaknesses are prioritized. Request examples of a resolved issue and the evidence that the change reached the affected environment. A policy document alone does not show that the process operates.

Separate a general CTO review from specialist testing. If the findings suggest a deeper security assessment, scope that work explicitly with authorization and appropriate expertise. A due-diligence report should never imply that limited inspection proves the absence of vulnerabilities.

Understand dependencies without confusing inventory and assurance

CISA's SBOM resources describe software component transparency and related practices. An inventory of components can help a reviewer understand what the product depends on. It does not by itself establish that those components are correctly configured, free of vulnerabilities, or legally suitable for every intended use.

Ask how the inventory is generated, which builds it represents, and how the team deals with unsupported components. Check whether important hosted services and commercial dependencies are documented separately. A package list will not necessarily describe every external service on which the business relies.

Flag licensing and ownership questions for qualified legal review. The CTO can identify where supporting evidence is missing and explain the operational dependency. That is different from issuing a legal conclusion about rights or transferability.

Test the continuity story with evidence

Ask the seller to explain a recent incident, including how it was detected, who responded, what customers experienced, and what changed afterward. Review the records behind that explanation. A useful review distinguishes the team's stated recovery plan from evidence that a recovery procedure has been exercised.

Investigate key-person dependencies. Can more than one authorized person deploy, investigate a failure, and manage critical accounts? Where are decisions and operating instructions recorded? Do the company's accounts actually control the repositories, domains, infrastructure, and monitoring services it relies on?

Do not ask the seller to expose passwords in a due-diligence folder. Verify ownership and access through appropriate evidence, and leave credential transfer to an agreed secure handover process if the transaction proceeds.

Write findings as decisions, not a list of complaints

Each material finding should state the observation, supporting evidence, business consequence, uncertainty, and proposed follow-up. Separate verified facts from the reviewer's interpretation. A concern supported only by an interview should not receive the same wording as one reproduced in the evidence.

For illustration, a product may have a reliable release process but no tested handover to a second operator. The useful finding is the continuity dependency and the evidence needed to reduce it. Describing the entire engineering function as poor would exceed what that observation supports.

Group follow-ups by when they matter: before the buyer can assess the issue, before an agreed handover, or during a later improvement program. Cost and effort estimates should include assumptions and confidence levels. Avoid presenting uncertain remediation work as a precise quote.

Appoint a reviewer who can explain the tradeoffs

The right fractional CTO should understand the product's business context and be comfortable identifying the limits of the review. Ask how they select samples, document evidence, handle conflicts of interest, and work with security and legal specialists. A provider that also wants the post-acquisition development work should make that potential incentive visible.

Compare fractional CTO providers and the distinction between CTO leadership and a development agency. When requesting an introduction, state the product type, intended operating model, available evidence, and review deadline. That gives a prospective reviewer enough context to propose a defensible scope.

Sources and scope

NIST and CISA primary sources were reviewed on September 25, 2026. The evidence-request structure is CHIEFORY's editorial framework. It is not a complete technical audit, certification, or substitute for specialist advice on a particular acquisition.