Backend Developer

Role Overview As a Backend Engineer at Floq, you will build and maintain the services that connect our exchange to the outside world. Floq is an OJK-licensed cryptocurrency exchange, and the systems you work on sit at the seams where money and identity move between parties: payment gateways that bring rupiah in and out, the KYC engine that verifies who our users are, and the trade engine that executes their orders. Your mission is to write clean, reliable Go services on AWS that make these integrations behave predictably under real load and real failure. Third-party APIs will time out, webhooks will arrive twice or out of order, and vendors will change their contracts. Your job is to make sure none of that ever reaches a user's balance or a regulator's report. Core Responsibilities Integration Engineering: Design, build, and maintain Go services that integrate with payment gateways (virtual accounts, bank transfers, e-wallets), KYC and identity verification providers, and Floq's trade engine and liquidity connectors.Serverless & Event-Driven Systems: Build and operate services on AWS Lambda, API Gateway, SQS, SNS, EventBridge, and Step Functions, with a strong grasp of idempotency, retries, dead-letter queues, and cold-start trade-offs.Transactional Integrity: Implement deposit, withdrawal, and order lifecycles as explicit state machines with clear ownership of every transition, so a payment is never credited twice and never lost.Reconciliation & Observability: Build automated reconciliation jobs against gateway settlement reports and trade engine fills, and instrument services with CloudWatch, structured logging, and alerting so anomalies surface before users notice.Security & Compliance: Handle credentials and PII correctly (Secrets Manager, KMS, IAM least privilege, encrypted data at rest and in transit) and work with the security and compliance teams to meet OJK and data protection requirements.Collaboration: Partner with mobile and web engineers on API contracts, with Product on integration scope, and with QA on test environments and vendor sandboxes. Technical Requirements Experience: 3+ years of professional backend development, with production Go (Golang) as your primary language for at least 2 of them.Go Proficiency: Solid command of idiomatic Go, including goroutines and channels, context propagation, error handling patterns, interfaces for testability, and Go modules.AWS Stack: Hands-on experience deploying and operating services on AWS, ideally Lambda-first: API Gateway, SQS/SNS, EventBridge, DynamoDB, RDS (PostgreSQL), S3, CloudWatch, IAM. Familiarity with infrastructure-as-code (Terraform, CDK, or SAM) is expected.Integration Experience: You have built against at least one external API that mattered, such as a payment gateway, banking API, identity provider, or exchange/matching engine, and you understand webhooks, signature verification, idempotency keys, and rate limiting from the inside.Data & Storage: Comfortable with relational modeling and transaction semantics in PostgreSQL, plus practical use of DynamoDB or Redis for high-throughput access patterns.Testing & Tooling: Unit and integration testing in Go, contract or mock testing against vendor sandboxes, Git, and CI/CD pipelines (GitHub Actions, CodePipeline, or similar).Bonus: Experience with FIX or WebSocket-based trading APIs, gRPC, or building financial ledgers; exposure to Indonesian payment rails (BI-FAST, QRIS, virtual accounts from local banks) is a strong plus. Soft Skills & Experience Fintech Mindset: Prior experience in fintech, payments, banking, or crypto is a strong plus. If not, you understand why "eventually consistent" is not an acceptable answer when the question is about someone's money.Ownership: You take an integration from vendor documentation to production monitoring, including the unglamorous parts: sandbox quirks, certificate rotations, and vendor support tickets.Debugging Under Uncertainty: Ability to trace a failed deposit across our services, a gateway's logs, and a bank's settlement file, and explain exactly where and why it went wrong.Communication: Clear written communication in Bahasa Indonesia and working proficiency in English, enough to read vendor documentation, write design notes and PR descriptions, and coordinate with local payment partners. Strategic "North Star" Priorities Every Rupiah Accounted For: Deposits, withdrawals, and trades must reconcile to the last rupiah and satoshi, every day, without a human opening a spreadsheet to make the numbers match.Boring Integrations: The best integration is one nobody talks about. You aim for services that degrade gracefully, recover automatically, and page someone only when a human decision is required. Critical Challenges You Will Solve The Duplicate Webhook Problem: A payment gateway sends the same settlement notification three times, twice out of order, once after a 20-minute delay. How do you credit the user exactly once, instantly, and prove it?KYC at Scale: How do you orchestrate a multi-step verification flow across an external KYC provider, document checks, and internal risk rules so that thousands of onboarding users get a fast answer while every rejection is auditable?Trade Engine Handoff: How do you guarantee that an order accepted by the API is either fully placed in the trade engine or cleanly rejected, even if a Lambda times out halfway through?