Spring Boot + Angular

The Angular + NestJS stack keeps the entire codebase in TypeScript: one language, one package ecosystem, shared types between frontend and backend. Spring Boot + Angular trades that uniformity for Java's deeper enterprise ecosystem: decades of library maturity, Spring Security's depth, and teams that are already standardized on JVM tooling. If the team is all-TypeScript or building a new product from scratch, NestJS removes the context-switching cost. If the organization already runs Java in production and has existing Spring expertise, Spring Boot is the natural backend choice.

Spring Boot starts with a baseline heap of roughly 256 MB to 512 MB even for a modest API, and the JVM process itself carries more overhead than a comparable Node.js service. On metered hosting (Railway, Fly.io), memory usage directly affects the monthly bill, so a busy Spring Boot app can cost noticeably more than the same workload on a Node backend. Flat-rate VPS hosting (Hetzner) absorbs this difference: a 4 GB VPS runs the JVM comfortably at a fixed monthly price regardless of heap fluctuations. For production workloads, plan for at least 1 GB of RAM dedicated to the Spring Boot process.

Because the frontend and backend run as independent services on different origins, browsers enforce CORS on every API call. Spring Security needs an explicit CORS configuration listing the Angular deployment URL as an allowed origin, and Angular's HttpClient needs withCredentials set to true if the API uses cookie-based sessions. The two configurations must agree on exact origins and credential handling; a mismatch shows up as opaque 403 errors in the browser console rather than clear server-side messages. This is the most common integration issue teams hit when first deploying the pair independently.

Yes. The decoupled architecture is the main reason this stack deploys the two services independently: Spring Boot exposes a REST API that any frontend can consume, so replacing Angular with React, Vue, or a mobile app means building a new client against the same endpoints. The deeper commitment is Spring Boot itself. Migrating off Spring means rewriting the backend in another framework (NestJS, Django, Rails), which is a full rewrite of the API layer, the database access patterns, and the security configuration. The frontend is the swappable side of this pairing; the backend is the load-bearing one.

Spring Security handles authentication and authorization within the Spring Boot app itself: form login, JWT tokens, role-based access, and OAuth2 resource server configuration all work without an external identity provider. Keycloak adds value when you need single sign-on across multiple applications, social login federation, or a standalone user management console that lives outside the app. For a single web app with standard user accounts, Spring Security paired with a managed provider (Auth0 or Clerk) is simpler and faster to set up. Keycloak earns its place when the organization already runs multiple apps that share an identity layer, or when self-hosted SSO is a requirement.