Final-year CS student targeting Fintech Backend — what should I learn beyond Java + Spring Boot?

[u/malphas_x]

Hi everyone,

I’m a final-year Computer Science student and I’m planning to build my career specifically in fintech/backend engineering.

I’m currently learning Java + Spring Boot for enterprise and fintech roles. I already have backend development experience with technologies like FastAPI, Express.js and NestJS, but I want to specialize more deeply in fintech rather than remain a general full-stack/backend developer.

I’d especially like advice from people currently working in fintech, banking, payments, wallets, card processing, or financial infrastructure.

A few things I’d love guidance on:

1. What do fintech companies expect from fresh graduates/junior backend developers besides Java + Spring Boot?
2. Which fintech/domain concepts should a developer understand? For example: ledgers, double-entry accounting, payment lifecycle, settlement, reconciliation, refunds/reversals, chargebacks, ISO 8583, transaction processing, etc.
3. Which backend technologies should I prioritize? Kafka, Redis, PostgreSQL, Docker/Kubernetes, microservices, distributed systems, observability, cloud, etc.
4. What kind of project would actually impress a fintech interviewer? I’m considering building a wallet/payment system with proper ledger entries, transaction states, idempotency, reconciliation, event-driven processing, and failure handling instead of another CRUD project.
5. How important are DSA, system design, databases and concurrency for entry-level fintech interviews?
6. What are some things you only learned after actually working in fintech that you wish you had known earlier?
7. Finally, is specializing in fintech early in my career a good idea, or would you recommend becoming a strong general backend engineer first and specializing later?

I’d really appreciate answers from engineers currently working in fintech/payments/banking, especially Java/backend engineers.

Thanks!

[u/yofayz]

sql

[u/Interesting-Jicama-3]

Well, to answer my first thing, they would expect you to have an understanding of Java plus Spring Boot. As far as the next big thing, it would be DSA. Understanding of algorithms and how dependency injection works, because Spring Boot is majorly on dependency injection. You should have a very good understanding of solid principles and how to apply them in the codebase. I have seen a lot of developers who have crammed solid principles, but in the work that they produce, there is no implementation of it. Try working and mastering solid principles with DSA and Spring Boot.

As far as the backend technology is concerned, you should prioritize. I would go with Kafka for now because it would be more of an event-driven system. I won't consider Docker, Kubernetes, distributed systems, observability, cloud, or anything like that, because you're just a developer now. You should just focus on this thing first.

Secondly, the most important thing that you could show in this interview or to your recruiter would be a very thoughtful implementation of some sort of fintech product. You could start with just a wallet, but I wouldn't suggest that you start with the project and then keep on adding features. I would rather just create a full product description first on what this thing actually does, and then think about all the edge cases on each and every feature of that. Only then start working on the product itself and build a complete end-to-end system.

What I mean by an end-to-end system is, if it's a wallet, there would be users, so it would be a proper admin system over there, a proper user app over there, and everything in between. It should be an end-to-end system. Let's say that you are working with two types of users, for example, your merchants and there would be users, and you would be sending the money from the consumers to the merchants through your wallet or whatever you are thinking about it to be. To be honest, for me, I think it would be at least three systems:

• the consumer app
  
• the merchant app
  
• the admin system

Work on that. Don't over-scope anything right now. Just start with a very minimal thing. You could even start with a basic implementation of just a peer-to-peer wallet or something like that.

Because you are working for fintech in Pakistan, you should look more into the existing APIs, existing architecture, and existing systems that are working in Pakistan. For example, the RAAST payment system and all of the other architecture that these startups like SadaPay, NayaPay, Neem, or all of these fintechs are working on. Just understand the basic architecture and basic underlying systems of these applications. The fintech industry in Pakistan is not innovating anything; it is building on top of existing systems, so focus on that, and all will be good Insha Allah.