A promising product can hide a difficult engineering reality. The demo works, customers are using it, and the roadmap sounds sensible – but the codebase may depend on one contractor, lack backups, expose personal data, or make every small change risky. Software technical due diligence is how investors, acquirers and founders find out what they are really taking on before a deal, fundraise or major build decision. This guide works as a practical technical due diligence checklist you can run against any product.
It is not a hunt for perfection. Most established products contain compromises, particularly where a team has been moving quickly. The useful question is whether those compromises are understood, proportionate and fixable, or whether they threaten delivery, security or the value of the business.
What software technical due diligence should answer
A good review turns a vague concern – “is the technology any good?” – into clear, decision-ready answers. It should establish whether the product can be maintained and developed at a reasonable pace, whether critical risks are being managed, and how much engineering work is likely to be needed after the transaction or investment.
That means looking beyond the user interface. A polished application can be built on fragile foundations, while an unglamorous codebase may be well structured, tested and easy for a new team to understand.
The findings should distinguish between immediate problems and normal technical debt. A missing automated test for a low-risk internal screen is not comparable to production credentials stored in source control. Treating every issue as equally serious is one of the fastest ways to produce an alarming but unhelpful report.
Start with the business and product context
Technical findings only make sense in context. Before reviewing repositories or cloud accounts, an assessor should understand what the software does, who uses it, where it is expected to go next and which parts of the product matter most.
For example, a marketing website and a multi-tenant SaaS platform have very different risk profiles. For the website, technical SEO, Core Web Vitals, content management and deployment reliability may be central. For a SaaS platform, access controls, the way tenant data is isolated, audit trails, background jobs and billing integrations may deserve much closer attention.
Ask the product team about the roadmap as well. A system that works well for its current users may need architectural changes before it can support a mobile app, enterprise single sign-on, international expansion or materially higher usage. That is not necessarily a reason to walk away. It is a reason to plan honestly.
Review the codebase, not just the technology names
A technology list tells you very little on its own. React, Node.js, PostgreSQL and AWS can support excellent products, but they can also be assembled carelessly. The quality of implementation, documentation and operational discipline matters more than whether the stack is fashionable.
Structure, ownership and maintainability
A code review should examine whether the application has a clear structure, sensible boundaries between features and services, and enough documentation for another experienced engineer to work safely. Look for consistent conventions, understandable naming, dependency management and a reasonable approach to configuration. This is the same ground covered by a code audit for startup teams before they scale, and running one ahead of a raise or sale often surfaces issues while they are still cheap to fix.
Ownership is equally important. Confirm that the company controls the source-code repositories, deployment accounts, domains, package registries and third-party service accounts. Access held only in an individual’s personal account creates a practical and commercial risk, even if the code itself is sound.
It is also worth checking the project history. Regular commits, peer review and meaningful pull requests can indicate a healthy delivery process. A repository with a single contributor, unclear changes and no documented release process may still be recoverable, but it needs closer scrutiny.
Tests and release confidence
Tests are not a badge of honour. They are evidence that a team can change important behaviour without relying entirely on manual checking. The right level varies by product, but high-risk workflows such as authentication, payments, permissions, calculations and data migrations should have meaningful automated coverage.
Review the delivery pipeline too. Can the team deploy predictably? Are there separate environments for development, testing and production? Is there a rollback route if a release causes an incident? A manual deployment process is not automatically unacceptable for a small product, but it becomes a constraint as the pace of change increases.
Assess security and data handling realistically
Security due diligence should focus first on the paths that could cause real harm: unauthorised access, data loss, service disruption and exposure of sensitive information. It should cover the application, infrastructure and the way people access both.
At a minimum, examine authentication and authorisation, password handling, multi-factor authentication for administrative systems, secret storage, encryption in transit, dependency updates, logging and alerting. For products handling personal or commercially sensitive information, check who can access production data and whether that access is controlled and recorded.
Backups deserve more than a tick in a spreadsheet. The key question is whether restoration has been tested. A backup that cannot be restored during an incident is only a theory. Similarly, an incident plan need not be a lengthy document, but the team should know who responds, how users are informed and how the cause is investigated.
A short security review cannot prove that software has no vulnerabilities. It can, however, identify obvious exposure, weak controls and areas where specialist testing is warranted.
Check architecture against the real scale of the product
“Will it scale?” is often asked too broadly. Scale might mean more users, more data, more integrations, more countries, more teams working on the code, or higher expectations for uptime. Each places different demands on the architecture.
A useful review maps the main request paths and data flows. Where does information enter the system? What happens when an external service is slow or unavailable? Which database queries are becoming expensive? Are background tasks isolated from user-facing work? Is the application monitored well enough to spot deterioration before users report it? The database layer is worth particular attention – our guide to designing databases that survive growth covers the schema and indexing decisions that tend to cause pain later.
Avoid assuming that a distributed architecture is inherently better. Splitting a modest product into many services can increase operational overhead and make it harder to diagnose failures. A well-organised monolith is often the right choice. The concern is not simplicity; it is whether the chosen design can support the next stage of the business without creating avoidable bottlenecks.
Look at performance, accessibility and search foundations
For customer-facing software, quality is not confined to the backend. Slow pages, inaccessible journeys and poor technical SEO can limit acquisition and conversion even when the underlying application is reliable.
The review should check page-weight discipline, image handling, rendering strategy, caching and Core Web Vitals where relevant. It should also assess semantic markup, keyboard use, colour contrast, form errors and screen-reader basics against the practical expectations laid out in a WCAG 2.2 AA compliance checklist. These are easier to build into a product than to retrofit under pressure.
For public websites, confirm that pages can be crawled and indexed appropriately, metadata is managed sensibly, redirects are controlled and no development settings accidentally block search engines. Technical SEO is not a substitute for useful content, but preventable implementation mistakes should not stand in the way of it.
Evaluate the team and operating model
Software risk is often people risk. A product can have clean code but still be vulnerable if only one person understands the deployment process, customer integrations or infrastructure decisions.
Ask how work is planned, reviewed and prioritised. Find out whether documentation is current, whether operational knowledge is shared, and whether there is a realistic handover path if key people leave. A small senior team can be highly effective, but it needs enough transparency that the business is not dependent on memory and goodwill.
Third-party dependencies need the same attention. Identify services for hosting, analytics, communications, payments, identity and monitoring, then understand their purpose, account ownership and fallback options. The goal is not to remove every dependency. It is to avoid discovering a critical one after it fails or becomes inaccessible.
Turn findings into a prioritised plan
The final output of software technical due diligence should be concise enough for decision-makers to use. Each finding should explain the issue, its likely impact, the evidence behind it and the recommended next step. Prioritise by severity and urgency rather than producing a long, undifferentiated list of improvements.
The most useful reports usually separate actions into three groups: issues to resolve before a transaction or launch, work to schedule in the first delivery period, and longer-term improvements that can be managed through normal product planning. Where the evidence is incomplete, say so plainly. Certainty invented for the sake of a report is worse than an explicit limitation.
A due diligence review should leave you with a realistic view of the product, not a generic score or a false sense of safety. If you are assessing an existing platform, planning a rebuild, or need a senior engineering view before a major decision, book a free consultation and we can help turn the code, infrastructure and delivery process into a practical plan.
