What an architecture review actually covers
An architecture review is not a code review. We are not reading your codebase line by line looking for SQL injection. We are evaluating the structural decisions that determine whether your application can be secured at all. The review examines four interconnected layers of your system.
Authentication and authorisation flows
How does a user prove their identity? How does your system decide what that user can access? These are the two most consequential security decisions in any fintech application, and they are often made early in development when the team is small and moving fast. We evaluate: whether your authentication chain has gaps (OTP verification that can be skipped, session tokens that do not expire, password reset flows that leak account existence), whether your authorisation model enforces object-level ownership checks consistently across every endpoint, and whether privilege escalation paths exist between user roles.
An authentication model that works for 500 users often breaks at 50,000. If your auth architecture does not scale securely, a pentest six months from now will surface the same classes of findings you will be forced to fix by restructuring, not patching.
Data flows and storage
Where does sensitive data enter your system? Where does it travel? Where does it rest? We map the complete lifecycle of your most sensitive data types: BVN and KYC data, payment credentials, transaction records, and personal information subject to NDPA requirements. We identify: data that is encrypted in transit but stored in plaintext, logging configurations that capture sensitive fields, third-party integrations that receive more data than they need, and backup strategies that create unencrypted copies of regulated data.
API design and integration patterns
Your API surface is your attack surface. We review: endpoint naming conventions and whether they expose internal architecture, request/response schemas for data over-exposure, rate limiting and throttling implementation, webhook verification mechanisms, and how your API handles partial failures in multi-step operations like payment processing. For payment platforms specifically, we evaluate whether your API design supports the transactional consistency required for financial operations or whether edge cases (timeout during disbursement, duplicate webhook delivery, partial refund processing) can produce inconsistent states.
Infrastructure and deployment
We review your cloud infrastructure configuration, network segmentation, secrets management, CI/CD pipeline security, and environment isolation. A staging environment that shares a database with production is an architecture flaw, not a vulnerability. A scanner will not find it. A pentest might stumble across it. An architecture review will identify it deliberately and recommend the structural change needed.
How it differs from a penetration test
A penetration test answers: "Can an attacker exploit your current application?" An architecture review answers: "Is your application designed in a way that makes exploitation difficult by default?" The penetration test finds symptoms. The architecture review finds root causes.
Consider a concrete example. A pentest discovers that your transfer API has a BOLA vulnerability. You fix that specific endpoint. An architecture review discovers that your API framework has no centralised authorisation middleware, which means every new endpoint your team builds will need manual authorisation logic. Fix the architecture, and the entire class of vulnerability becomes unlikely across your application.
Pentests find what is broken. Architecture reviews fix why it broke.
If your pentest findings follow a pattern (multiple BOLA findings, repeated authentication gaps, inconsistent input validation), the root cause is almost always architectural. The most cost-effective path is often an architecture review followed by a pentest to verify the structural changes.
When to get an architecture review
Before launch
If your fintech is six to twelve weeks from a public launch, an architecture review identifies structural weaknesses while they are still cheap to fix. Restructuring your authorisation model costs one sprint in pre-launch. It costs a quarter post-launch when you have live users, active transactions, and backward compatibility constraints. See our guide on security audits before launch.
Before fundraising
Sophisticated investors, particularly at Series A and beyond, conduct technical due diligence. An architecture review report demonstrates that your security posture is not just tested but designed. It signals engineering maturity in a way that a pentest report alone does not. For more, see our guide on security before fundraising.
After an incident
If you have experienced a breach or near-miss, a pentest alone tells you whether the specific attack vector is closed. An architecture review tells you whether the structural conditions that enabled the incident still exist in other parts of your application. Post-incident, the question is not just "is the hole patched?" but "why did the hole exist, and where else does the same pattern appear?" For incident response guidance, see our after a breach guide.
Want to know if your architecture needs a review before your next pentest?
Discuss an Architecture ReviewWhat you receive
The architecture review deliverable is a structured report covering: a system architecture assessment with annotated diagrams of your current design, identified structural weaknesses categorised by risk and remediation effort, specific recommendations with implementation guidance for each weakness, a prioritised roadmap that sequences changes by risk reduction and engineering effort, and compliance alignment notes mapping architectural decisions to CBN, PCI DSS, and NDPA requirements.
This is not a theoretical document. It is a technical brief your engineering team can execute against. Each recommendation includes enough specificity that a senior developer can estimate the implementation effort and scope it into sprint planning.
Related reading
Blog: How a Simpa Labs pentest works · Zero trust architecture for fintechs · Microservices security
Guides: Security before fundraising · OWASP for fintech · Security checklist
Services: Architecture review · Penetration testing · API security