Job type: Full Time

Department: Engineering

Work type: On - Site

Remote(Bengaluru)

Why This Role Matters

JustCall is the communication layer for tens of thousands of revenue teams - calls, SMS, and increasingly AI voice agents that talk to customers in real time. Weve earned a decade of scale. Weve also inherited a decade of architecture: a large PHP/JavaScript surface area, an integrations layer thats hard to extend, and a voice stack built for a pre - LLM world.

We are not looking for people to staff a backlog. We are looking for a handful of engineers who have already built systems at scale, who can walk into a ten - year - old codebase and a green - field voice - agent problem in the same week, and who want the rare thing: full ownership of a hard problem, with the autonomy and the equity to match.

If you read the four problems below and feel the itch to start sketching the design, this is for you.

Tracks

Every Principal Engineer shares the bar above. Tracks describe where youll start and the depth well index on. Strong candidates often blur two tracks - thats welcome.

Track A - Voice Agent Platform Principal Engineer

Build the voice - agent platform: low latency, natural conversation, production - grade accuracy.

Your charter. Own the architecture of JustCalls next - generation voice agents end - to - end from the telephony edge to the model orchestration to the evaluation harness that tells us whether an agent is actually good.

What youll own in your first 6 12 months

- A streaming, cascaded voice pipeline (ASR LLM TTS) with end - to - end response latency under ~800ms and a credible path toward the ~PHONE_NUMBERms range where callers stop noticing theyre talking to AI.
- Turn - taking and barge - in that feel human - semantic endpointing, interruption handling, and full - duplex audio - not naive VAD silence timers.
- An evaluation and observability stack for voice: latency budgets per stage, transcription/WER tracking, hallucination and instruction - following evals, and replayable call traces.
- The orchestration layer:



tool/function calling, RAG over customer knowledge, guardrails, and graceful fallback when a model or vendor degrades.

Must - haves

- Deep, hands - on experience building real - time or streaming systems - voice, video, RTC, audio, or low - latency ML serving. You understand where milliseconds go.
- Working knowledge of the modern agent stack: LLM orchestration, function/tool calling, streaming token pipelines, ASR/TTS, and how to evaluate non - deterministic systems.
- Youve shipped something users talked to (or otherwise interacted with in real time) and made it quick and reliable.

Track B - Platform Integrations Principal Engineer

Turn the integrations module into a platform other teams (and partners) build on.

Your charter. Re - imagine how JustCall connects to the outside world - CRMs, helpdesks, dialers, webhooks, and the long tail of partner APIs - as a resilient, observable, self - serve platform rather than a pile of bespoke connectors.

What youll own in your first 6 12 months

- A redesigned integrations platform: a typed connector framework, a sync/eventing model that survives third - party rate limits and outages, idempotency and replay, and first - class observability per connector.
- A migration path off the current integrations module that doesnt break existing customers - incremental, measurable, reversible.
- The internal developer experience that lets a new integration go from spec to production in days, not quarters - SDKs, contracts, sandboxes, and tests.
- Patterns for API design, versioning, and backward compatibility that the rest of engineering adopts.

Must - haves





- Youve built platforms or developer - facing systems that other engineers built on top of - not just features.
- Deep experience with distributed systems fundamentals: queues, idempotency, eventual consistency, retries/backoff, webhook delivery, and failure isolation.
- A track record of large - scale migrations done safely, with rollback and zero - downtime cutovers.

Track C - Core Systems Scale Principal Engineer

Pay down a decade of debt and harden the core for the next decade of scale.

Your charter. Take the core JustCall platform - the PHP monolith and the Node services around it - and turn ten years of accreted complexity into a clean, observable, scalable foundation, without stopping the business.

What youll own in your first 6 12 months

- A decomposition strategy for the monolith: where to carve services, where to leave the monolith, and a strangler - fig plan that ships value every sprint.
- Reliability and performance wins on the hottest paths - p99 latency, database hotspots (MySQL/MongoDB), and the noisy - neighbor problems that come with a shared monolith.
- A migration of legacy surfaces (e. g. , PHP modern services / front - end) with safety nets: feature flags, shadow traffic, automated regression, and clean rollback.
- Raising the floor on engineering fundamentals: CI/CD, test strategy, observability (we run CubeAPM), and on - call health.

Must - haves

- Youve operated and evolved a large, high - traffic system in production and know what breaks at scale - and how to fix it without a big - bang rewrite.
- Strong instincts for incremental migration and risk management; youve led at least one multi - quarter modernization that actually landed.
- Fluency in the messy middle: profiling, query optimization, caching, queueing, and capacity planning.

Disclaimer : This job posting has been aggregated from external source. Role details, content, and availability are subject to change. Applicants are advised to confirm the latest information directly on the company website before applying.

📌 Staff / Principal Engineer (Karnataka)
🏢 Just Call
📍 Karnataka