Backend Engineer

AntarAI · Remote

Early-stage CRM/marketing SaaS. Primary backend engineer across a Node.js/Express + MySQL stack with RabbitMQ for async workflows and Azure OpenAI integration. Responsible for roughly 60–80% of backend code, owning design and implementation of several core systems.

• —Event-driven architecture: Designed the RabbitMQ topology: topic exchanges, wildcard routing, durable queues, manual ACKs, and dead-letter exchanges for retry and failure handling. Most async work in the system — notifications, AI scoring, activity ingestion — runs through this layer.
• —Materialized leads view: The main lead listing query joined 4 tables and was causing p95 latencies of 800ms–1.5s under modest load, with connection pool exhaustion. Redis caching wasn't viable due to complex filter combinations.
• —Scheduled campaigns via RabbitMQ TTL + DLX: Replaced a naive cron-based scheduler with a delay queue pattern: messages published with TTL equal to the wait time auto-route to the live queue on expiry. Eliminated the single-point-of-failure scheduler. Added token-bucket rate limiting on consumers to avoid hitting external API rate limits, and DLQs for failed sends.
• —AI signal pipeline: Built a lead intelligence subsystem:
• —Telephony and credit system: Integrated Plivo for VoIP. Built a credit system where tenants top up via Razorpay and call sessions decrement user balances with row-level locking to prevent overspend. Handled subaccount creation, SIP URL generation, call-to-lead linking, and transcript storage.
• —RBAC and multitenancy: Refactored permissions into scope-based model with record-level enforcement: scope_all, scope_owner, scope_assigned. Implemented in middleware and service logic. Tenant data isolation enforced across all endpoints.
• —Other: EAV model for tenant-defined custom fields with flattened JSON reads in materialized views. Recursive filter compiler translating frontend filter payloads to parameterised SQL. WhatsApp + email notification pipeline. Razorpay webhook handling. Data import scripts (idempotent, with upserts and foreign key resolution).

B.Tech, Computer Science

Vivekananda Global University