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Frequently asked questions

What Java skills matter most for payment and ledger systems?

Prioritize reasoning about correctness: BigDecimal scale and rounding, database isolation, idempotency, and durable audit records. Ask candidates to walk through a timeout that occurs after a payment provider accepts a request. For ledger work, discuss balanced postings, reversal entries, and invariant testing. Framework knowledge matters, but it should support explicit financial rules rather than substitute for them.

How should a Spring Boot payment API prevent duplicate charges?

Use a persisted idempotency key with a defined scope, request validation, and a stored outcome. Database constraints should help enforce uniqueness under concurrent requests. Coordinate the design with the payment provider's own idempotency behavior and timeout semantics. A transactional outbox can reliably publish local state changes, but it does not make an external charge part of your database transaction.

Is Kafka exactly-once processing enough for financial transactions?

Kafka's exactly-once features apply within defined Kafka processing boundaries; they do not automatically cover database writes or external payment calls. Financial workflows still need deduplication, durable state transitions, and reconciliation. Ask how consumer retries, offset commits, and out-of-order events interact with your ledger. Test replay scenarios where a crash happens between an external side effect and local confirmation.

How can a Java engineer work within our SOC 2 controls?

We're comfortable working inside a client's SOC 2 security controls. Describe your access approval process, repository permissions, change reviews, and evidence requirements before onboarding. For a Spring application, clarify secrets handling, production access, and rules for logging transaction data. An NDA and full IP assignment are signed before code access; your organization retains its own control procedures.

What should we prepare before hiring Java developers for reconciliation?

Bring sample file schemas with sensitive data removed, matching rules, cutoff times, and exception workflows. Include your Spring Batch version, job restart requirements, and how corrected source files are handled. Book a 15-minute call to discuss that scope. Most teams interview matched engineers within a week of the first call, and engineers work your team's hours.

Are your developers really based in the US?

Yes. Every engineer lives and works in the United States. No offshore subcontracting and no hand-offs to another team. That's written into the contract.

How fast can someone start?

Most teams interview matched engineers within a week of the first call. Start dates depend on your interview process.