Back End Developer

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Minimum Qualification: Master’s degree in computer science

Number Of Opening: 3

**Job Overview**:

You’ll architect and build the core rails of a multi-channel messaging platform: ingest → preprocess → queue → dispatch → deliver → observe, at millions of messages/hour, across WhatsApp (Meta), Google RCS, and SMS operators.

Responsibilities:

·        Design & build microservices for message ingestion, validation/preprocessing, enrichment, routing, dispatch, delivery receipts, and retries.

·        Concurrency at scale: implement multi-process/async workers; tune throughput, back-pressure, and graceful shedding.

·        Queueing & orchestration: model queues, exchanges, routing keys, DLQs, TTLs, idempotency tokens in RabbitMQ (bonus: Kafka familiarity).

·        Channel adapters: production-grade connectors for WhatsApp Cloud API, Google RCS Business Messaging, SMPP/operator REST; handle webhooks, HSM/template policies, rate limits, and error taxonomies.

·        Reliability patterns: implement at-least-once semantics, retry with jitter, outbox/inbox patterns, dedupe, and exactly-once where feasible.

·        Observability: structured logging, tracing (OpenTelemetry), metrics (Prometheus), SLOs, red/black dashboards, and alerting.

·        Data & storage: design schemas for message states, audit trails, and compliance logs (Postgres); scalable analytics/time-series (e.g., ClickHouse/Timescale).

·        Security & compliance: secrets management, key rotation, PII handling, and alignment with TRAI/DLT & operator policies.

·        CI/CD & DevEx: Docker images, K8s manifests/Helm, GitHub Actions, canary/blue-green, migration discipline.

·        Performance ownership: load testing, capacity planning, cost/throughput tuning.

Required Qualifications & Skills

·        Language: Python 3.11+ (asyncio), FastAPI, Pydantic, aiohttp/httpx, uvicorn/gunicorn

·        Workers/Queues: RabbitMQ (mandatory), Celery/Dramatiq/Arq (your call), Redis (caching/locks)

·        Data: Postgres (+ SQL expertise), ClickHouse/Timescale (nice-to-have)

·        Cloud & Ops: Docker, Kubernetes, Helm, Prometheus/Grafana, OpenTelemetry

·        Protocols: Webhooks, REST, SMPP, OAuth/JWT, WebSockets (optional)

·        Open to Go candidates with strong concurrency + RabbitMQ; or Rust for high-perf dispatchers. But Python is preferred for velocity and our current stack.

Must-have qualifications

·        5–10 years backend experience; 3+ years in Python in production microservices.

·        Proven high-throughput systems experience (≥50k msgs/min or equivalent event workloads).

·        Deep knowledge of queues (RabbitMQ): exchanges, bindings, nack/requeue patterns, DLQ/TTL, priority queues.

·        Strong async + multiprocessing fundamentals; profiling & tuning (CPU vs I/O bound).

·        API design/maintenance at scale; webhook reliability (retries, signatures).

·        Solid DB design, query tuning, and idempotency strategies.

·        Observability mindset: traces, metrics, structured logs; incident response.

·        Nice-to-have

·        WhatsApp Cloud API / RBM (RCS) / SMPP operator integrations in production.

·        Rate-limiting algorithms (token/leaky bucket), distributed locks, and scheduler design.

·        Experience with Kafka, NATS, or ClickHouse.

·        Familiarity with TRAI DLT template flows & messaging compliance in India.