Spring Boot vs Elysia for Solo Developers

Quick Comparison

Spring Boot Overview

Spring Boot simplifies enterprise Java development by wrapping the Spring Framework with auto-configuration, embedded servers, and opinionated defaults. Pick your dependencies from Spring Initializr, and you get a production-ready application scaffold with security, database access, and monitoring configured automatically.

The framework's ecosystem depth is unmatched in backend development. Spring Security handles everything from basic auth to OAuth2 to SAML. Spring Data abstracts over a dozen database technologies. Spring Cloud provides service discovery, circuit breakers, and configuration servers. If an enterprise pattern exists, Spring has a maintained solution for it.

For complex domain-driven applications, Spring Boot provides the infrastructure to manage that complexity. Dependency injection, aspect-oriented programming, transaction management, and event handling all work together to keep business logic clean. The tooling support in IntelliJ IDEA makes navigating and refactoring large Spring applications practical.

Elysia Overview

Elysia is designed from the ground up for Bun and speed. It uses Bun's native HTTP handling and compilation to deliver throughput that rivals compiled language frameworks. The API surface is small, the learning curve is short, and the type safety is exceptional.

What makes Elysia remarkable is the type inference. Define your schemas, and types flow through your entire request pipeline automatically. Validators, middleware, guards, and handlers all share the same type context. The Eden Treaty feature generates a fully typed API client directly from your server code, creating end-to-end type safety between your frontend and backend.

The developer experience is refreshingly simple. Create an Elysia instance, define routes with schemas, add plugins for auth or CORS, and you have a working API. No XML configuration, no annotation scanning, no bean wiring. The framework does one thing and does it well.

Key Differences

Startup and resources. Elysia on Bun starts in milliseconds and runs in 30-80MB of RAM. Spring Boot takes 5-30 seconds to start and needs 200-500MB minimum. For local development, the difference means Elysia gives you instant feedback while Spring Boot has you waiting. For production, it means cheaper infrastructure.

Complexity capacity. Spring Boot is built for complexity. Distributed transactions, event-driven architectures, batch processing, complex security policies. Elysia handles HTTP request/response patterns well but doesn't provide tools for enterprise architectural patterns. If your application is genuinely complex, Spring Boot manages that complexity better.

Developer velocity. For a typical REST API, Elysia gets you from zero to deployed faster than Spring Boot by a significant margin. Fewer concepts to learn, less configuration to manage, faster iteration cycles. Spring Boot's velocity improves as application complexity increases and its built-in solutions save you from reinventing enterprise patterns.

Type safety philosophy. Elysia uses runtime schema validation with compile-time type inference. Spring Boot uses Java's type system with additional validation annotations. Elysia's approach requires less code for the same safety. Spring Boot's approach is more traditional and relies more on IDE support.

Deployment options. Elysia runs on Bun, which limits hosting options compared to Spring Boot's JVM. Spring Boot JARs run on any JVM, which is available virtually everywhere. Bun support in hosting platforms is growing but not universal. For deploying to Docker or VPS, both work fine.

Learning investment. Elysia takes hours to learn. Spring Boot takes weeks to months to be genuinely productive. The concepts in Spring (DI, AOP, bean lifecycle, auto-configuration) are powerful but have a significant upfront learning cost. For a solo developer who wants to ship today, Elysia's low barrier is a real advantage.

When to Choose Spring Boot

• Your application has genuine enterprise requirements (complex auth, batch processing, event streaming)
• You're experienced with Java/Kotlin and productive in the Spring ecosystem
• You need integration with enterprise systems (LDAP, messaging queues, legacy services)
• You're building a large application where Spring's patterns prevent technical debt
• Long-term commercial support and stability are important

When to Choose Elysia

• You want the fastest possible TypeScript API development
• You value end-to-end type safety with minimal boilerplate
• You're building a modern API consumed by a frontend you also control
• You want fast startup, low memory usage, and quick iteration cycles
• You prefer learning a framework in hours, not weeks

The Verdict

For solo developers, Elysia at 7/10 edges past Spring Boot at 6/10. The reasoning is practical: solo developer projects rarely need enterprise-grade features, but they always benefit from faster development cycles and lower operational overhead.

Spring Boot is a powerful framework designed for teams building complex enterprise systems. When you're a solo developer, much of that power goes unused while you still pay the costs of startup time, memory consumption, and configuration complexity. It's like driving a semi truck to the grocery store.

Elysia matches the scale of what most solo developers actually build. A TypeScript API that validates requests, handles auth, serves data, and runs cheaply. If your project genuinely needs Spring Boot's enterprise capabilities, use it. But if you're honest about your requirements, Elysia probably covers them with less friction and lower cost.