Senior Back End Developer

About Blostem

Blostem is the banking infrastructure layer for India's fintechs. We power Fixed Deposits, Recurring Deposits, Bonds, and UPI credit-line products through a single SDK that lets platforms like MobiKwik, Upstox, Jupiter, Zerodha (27+ partners) plug into 10+ partner banks (Suryoday, Unity, Shivalik, Utkarsh) and NBFCs (Bajaj, Shriram, Mahindra) live in 7 days, no upfront cost, revenue-share model. We replace the 35 engineers and 35 crore that fintechs would otherwise spend building bank integrations, KYC, and reconciliation themselves.

About the role

The backend is where the money actually moves. You'll own the partner API that fintechs hit, the bank and NBFC integration layer abstracting 10+ heterogeneous partners (REST, SOAP, SFTP file-drops whatever the bank exposes), the KYC orchestration that ties together Digio / IDfy / Hyperverge and bureau checks, and the ledger, reconciliation, and settlement pipelines that have to balance to the paisa, every day, audited by partners, banks, and regulators. We need someone who's built systems where correctness beats cleverness, who can debug a reconciliation mismatch as confidently as a 5xx spike, and who's seen what breaks at scale in regulated workloads.

What you'll do

• Build and own backend services in Node.js 22 + TypeScript (strict) the public partner API, the bank integration layer, KYC orchestration, payment rails, reconciliation, settlement, and reporting jobs.
• Design and evolve Postgres schemas for ledgers, bookings, mandates, and audit logs. Idempotency, immutability, and EXPLAIN ANALYZE are daily tools.
• Integrate with 10+ banks and NBFCs (Suryoday, Unity, Shivalik, Utkarsh, Bajaj, Shriram, Mahindra and others) across REST, SOAP, and SFTP. Abstract them behind a clean internal contract so partner-facing APIs stay consistent.
• Integrate KYC / eKYC providers (Digio, IDfy, Hyperverge), payment rails (UPI / NPCI, NEFT, IMPS, eNACH), Account Aggregator (AA), CKYC, and bureau APIs.
• Build event-driven pipelines for booking, reconciliation, settlement, EOD/SOD reports, regulatory filings with Redis, BullMQ, Kafka, NATS, or SQS pick the right primitive per problem.
• Write services using modern frameworks Fastify, Hono, NestJS, tRPC and know why you picked one over another.
• Instrument everything for SLA, audit, and regulator-friendly observability OpenTelemetry, structured logs, Prometheus / Grafana, Sentry. Logs are an evidence trail, not just a debugging aid.
• Own deployment Docker, Kubernetes / ECS, GitHub Actions, Terraform / Pulumi. AWS primarily.
• Use Claude Code, Cursor, GitHub Copilot as daily tools for codebase navigation, test generation, refactors, debugging stack traces, generating migrations.

Must have

• 58 years writing production Node.js. At least 3+ years in TypeScript (strict).
• Production experience in fintech, payments, lending, deposits, or banking you've shipped systems where money correctness, idempotency, audit trails, and reconciliation were table stakes.
• Strong API design REST conventions, idempotency keys, pagination, versioning, contractual error responses, partner-facing SLAs. You've broken APIs before and learned from it.
• Deep Postgres indexes, query planning, transactions, isolation levels, connection pooling, double-entry-friendly schemas. You don't reach for an ORM to hide your SQL gaps.
• Async / event-driven systems queues, workers, retries, idempotency, exactly-once vs at-least-once tradeoffs, dead-letter handling.
• Experience integrating with multiple external partners (banks, KYC, payment, bureau) handling heterogeneous APIs, flaky partner uptime, and SLA mismatches.
• Comfort with Docker, CI/CD, at least one cloud (AWS preferred).
• AI tooling in daily workflow Claude Code, Cursor, Copilot. You should be able to describe how you use them on real backend tasks (e.g. "Claude Code generated and ran the migration for the multi-tenant rewrite, I reviewed the diff").
• Strong debugging you can read a flamegraph, a heap snapshot, or a pg_stat_activity dump without panic.

Nice to have

• Direct experience with Indian banking rails UPI / NPCI, NEFT, IMPS, AA (Account Aggregator), CKYC, eNACH, eSign.
• Worked with Indian SFBs / NBFC API ecosystems Suryoday, Unity, Shivalik, Utkarsh, Bajaj, Shriram, Mahindra, or similar.
• Familiarity with RBI / SEBI / NPCI regulatory expectations audit logs, data residency, retention, reporting cadence.
• Double-entry ledger experience bookings, accruals, reversals, settlements, daily balance proofs.
• Python for data / ML / regulatory-reporting paths FastAPI, asyncio, Pydantic, Pandas.
• Background in Go or Rust for hot paths.
• Vector DBs pgvector, Pinecone, Weaviate, Qdrant (for internal search / support tooling).
• IaC Terraform, Pulumi, CDK.
• Built and operated services at >1k RPS sustained.
• OSS contributions to Node, Fastify, Hono, Drizzle, or related ecosystem.

How we work

• Ship to prod multiple times a day. Feature flags over long-lived branches.
• AI-first Claude Code, Cursor, Copilot are baseline tools, not perks. We expect you to be 23x faster than a non-AI engineer on routine work.
• Money-correctness is non-negotiable. Speed is for everything else.
• On-call is shared and respected. We fix root causes, not just incidents.
• Strong opinions, weakly held. Argue in PRs, not in meetings.