Software Development Engineer II - Multichannel Agents

About the role

Blue Machines AI builds a production AI agent platform that large enterprise customers use to automate customer conversations at scale. Today a single agent may take a phone call, answer a WhatsApp message, pick up a chat on a customer's website, or join a video session — and it has to behave like the same agent everywhere: same knowledge, same business rules, same memory of who the customer is and what they asked for five minutes ago on a different channel.

The Multichannel team owns that layer. We build the channel adapters, the session and conversation model that sits above them, and the media handling that lets an agent move between text, audio, video, images and documents. Every channel has its own protocol, its own constraints and its own way of failing: telephony cares about milliseconds and codecs, WhatsApp about template approvals, 24-hour session windows and delivery receipts, the web widget about reconnects, flaky mobile networks and embedding inside someone else's site. A bug here isn't a broken screen — it's an enterprise customer's support line going silent.

We're hiring an SDE II to help build this team's foundations. You'll design and ship channel integrations end to end, own them in production, and help define the abstractions that make adding the next channel a week of work instead of a quarter.

What you'll do

• Build and own channel integrations — WhatsApp Business Platform (Cloud API), telephony (SIP/PSTN via carriers and CPaaS providers), the embeddable web chat widget, and in-app/web voice and video over WebRTC — from API design through production on-call.
• Design the unified conversation layer: a channel-agnostic session, message and identity model so the agent runtime sees one conversation regardless of where it came from, with clean handling of channel switches (e.g., a call that continues on WhatsApp) and cross-channel context.
• Handle multimodal input and output: text, voice notes, live audio streams, video, images, documents, location, interactive messages (buttons, lists, carousels) — normalising inbound media for the agent and rendering agent responses correctly for each channel's capabilities and limits.
• Build the realtime plumbing: WebSockets/WebRTC for live audio and video, streaming responses to the widget, and the hooks into the voice pipeline (STT, TTS, turn detection, barge-in) owned with Team Orca.
• Make delivery reliable: idempotent webhook ingestion, retries and dead-letter handling, ordering guarantees, delivery/read-status tracking, rate-limit and quality-tier management on WhatsApp, and graceful degradation when a provider is down.
• Ship the web widget as a product: lightweight embeddable SDK, theming and configuration from our Console, reconnect and offline behaviour, attachment uploads, accessibility, and security for running inside third-party pages.
• Own it in production: instrument latency, delivery success and error rates per channel; build dashboards and alerts; debug live incidents across our services, carrier/BSP logs and customer networks.
• Write design docs, review code, and raise the bar on testing for asynchronous, event-driven systems. Use AI coding tools as a normal part of how you work — with no compromise on quality.

What we're looking for

• 3–6 years building and running backend or full-stack systems in production, with clear ownership of at least one service end to end.
• Strong in one of Python, Go, Node.js/TypeScript or Java, and comfortable reading the others.
• Solid fundamentals in distributed, event-driven systems: queues/streams (Kafka, Redis Streams, RabbitMQ, SQS or similar), async processing, idempotency, retries, and consistency trade-offs.
• Hands-on experience integrating at least one messaging or communication channel — WhatsApp Business API, SMS, telephony/CPaaS (Twilio, Plivo, Exotel, Vonage or similar), or a chat platform — including webhooks, signature verification and provider-specific quirks.
• Working knowledge of realtime protocols: WebSockets, and ideally WebRTC or streaming media.
• Comfortable designing APIs and data models (SQL and NoSQL) that will be used by other teams and by customers.
• Production instincts: you reach for logs, traces and metrics before guessing, and you design for failure because providers will fail.
• Clear written communication — your design docs and incident notes should stand on their own.

Nice to have

• Built a chat or voice widget/SDK embedded in third-party websites or mobile apps.
• Experience with SIP, RTP, media servers (FreeSWITCH, Asterisk, LiveKit, Janus, mediasoup) or codecs and audio processing.
• Familiarity with WhatsApp specifics: template messages, 24-hour customer-service window, interactive messages, Flows, BSP integrations, quality ratings and messaging limits.
• Experience with LLM-based or conversational AI products, especially streaming responses or voice agents.
• Exposure to additional channels: RCS, Instagram/Messenger, Telegram, email, or in-app chat.
• Performance and load-testing realtime systems at high concurrency.

Why Blue Machines

You'll be an early engineer on a new team with a broad charter — the abstractions you design will decide how every future channel gets built. You'll work on hard, visible problems at enterprise scale, close to the architects and the people who own the platform, with real ownership over what ships.