Backend Engineer at Wise: what they ask

UK fintech for low-cost international money transfers. Backend stack: Java/Kotlin, AWS/Kubernetes, PostgreSQL, Kafka.

Public reports + Wise’s official system-design guide. Add yours to keep it fresh.

The process

1. Take-home task, then reviewed: ~15-20m walkthrough (approach, tradeoffs, improvements) + live extension (the interviewer adds requirements, you evolve the code).
2. Pair programming: circuit-breaker-style problems with an OO skeleton to complete.
3. System design (~1h, 2 engineers): you get a product task, propose the high-level architecture, then flesh out data structures/logic. "We don’t expect a perfect solution."

What they ask

• Extend/refactor your own take-home in real time.
• OO pair programming (resilience: circuit breaker, retry).
• System design: build a performant, maintainable, extensible system for a real problem.

How they behave

Fewer algorithm puzzles, more: how you reason in production. They assess your reasoning, how you frame the problem, articulated tradeoffs, communication/collaboration. "Practical application, not memorization — no textbook questions."

How to prepare

• Microservices (design, deploy, tracing, monitoring) + distributed systems.
• Sync/async communication, eventual consistency, idempotency, concurrency, data consistency.
• High transaction volume, scalability/availability, storage/DB, error handling.
• Start simple and iterate; ask clarifying questions; state assumptions and how you’d test.