VoisX
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EngineeringBangalore, India (Hybrid)Full-time

Backend Engineer

VoisX's platform runs live voice agents that handle real phone calls end to end — routing, tool use, knowledge retrieval, and billing all have to hold up under real call traffic. You'll work on the FastAPI backend and the LangGraph agent-orchestration layer that powers it.

  • Python
  • FastAPI
  • PostgreSQL
  • LangGraph
  • Redis
  • Qdrant
  • Kubernetes
  • Twilio / Plivo

What you’ll do

  • Build and extend FastAPI services that back the agent platform: organizations, projects, billing, telephony, and the admin console
  • Work on the LangGraph agent-execution engine — tool calling, escalation, conversation state, and the config-driven graph builder
  • Design PostgreSQL schemas and write Alembic migrations that hold up under multi-tenant load
  • Integrate voice carriers (Twilio, Plivo) and LLM providers (OpenAI, Anthropic, Gemini) behind consistent internal interfaces
  • Wire up RAG retrieval over Qdrant and analytical queries against BigQuery/Snowflake for customer-facing analytics
  • Add timeouts, retries, and observability (Prometheus, OpenTelemetry) so failures in one dependency don't take down a call
  • Ship changes to a Kubernetes-deployed service with real on-call implications — you'll own what you build in production

What we’re looking for

  • 3+ years building production backend services in Python
  • Solid experience with FastAPI or a comparable async web framework, plus SQLAlchemy/Alembic or similar ORM + migration tooling
  • Comfortable designing relational schemas and writing migrations you'd trust against a live, multi-tenant database
  • Working knowledge of Docker and Kubernetes-based deployment
  • Experience integrating third-party/webhook-based APIs (payment, telephony, or similar) and handling their failure modes
  • You reason about concurrency, timeouts, and retries by default, not as an afterthought

Nice to have

  • Experience with LLM-based agent frameworks (LangGraph, LangChain) or building tool-calling agents
  • Familiarity with vector databases (Qdrant, pgvector) and RAG pipelines
  • Experience with real-time/streaming systems — WebSockets, telephony media streams, or similar
  • Exposure to Terraform, Vault, or infrastructure-as-code in a cloud environment (Azure/AKS)

Apply for Backend Engineer

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