●Next.js + Fintech

Next.js has become the framework of choice for fintech applications because it uniquely addresses the tension between performance requirements and security constraints. Trading platforms need sub-100ms response times—users make split-second decisions based on price movements, and latency erodes trust. But financial applications also face the most stringent security requirements in software: PCI-DSS, SOC 2, and often industry-specific regulations. Next.js 14's architecture resolves this tension elegantly. Server Components keep sensitive business logic and data transformations on the server, dramatically reducing the attack surface compared to traditional SPAs where financial calculations might run client-side. The middleware layer provides a single enforcement point for authentication, authorization, and audit logging—critical for compliance audits where you need to demonstrate consistent security controls. Edge Functions position your application within 50ms of users globally while Server Actions handle mutations with built-in CSRF protection. For fintech specifically, the streaming architecture is transformative. A trading dashboard can serve its navigation and layout shell instantly from the edge, then stream in real-time price data from origin servers in compliant regions. Users see a responsive interface immediately while live data populates—no loading spinners that make traders anxious. This isn't just UX polish; it's a competitive advantage when users choose platforms based on perceived speed and reliability.

Fintech projects demand security-first architecture from day one—retrofitting compliance is expensive and risky. I begin every engagement by mapping the regulatory landscape: Which data is considered sensitive? What are the audit requirements? Where can data reside geographically? These constraints shape every technical decision. The Next.js application structure encodes security boundaries explicitly. Middleware handles authentication and authorization before any route handler executes. Sensitive routes are grouped into protected segments with explicit access control. Server Components ensure that financial calculations and sensitive data transformations never execute in the browser. For payment processing, I implement Stripe Elements from the start—there's no scenario where handling raw card data yourself is worth the PCI burden. The architecture assumes you'll need MFA, session timeouts, and re-authentication flows, building these into the authentication layer rather than bolting them on later. Every financial application needs comprehensive audit logging, so I implement structured logging middleware that captures user context, request details, and response status for every operation. These logs ship to immutable storage (S3 with Object Lock, for example) meeting the 7-year retention requirements common in financial regulations. Testing strategy emphasizes integration tests that verify complete user flows—not just unit tests that might miss security gaps. A test that verifies 'user can transfer funds' must also verify that audit logs were created, session was validated, and amount limits were enforced.