Senior Backend Engineer - Communications Remote

Close moves 7 million minutes of call recordings, millions of sales emails, and a steady volume of SMS through our pipes every month. The Communications team owns that entire surface — and the job got trickier in the last year, because real‑time calling is now a real‑time AI problem. When a customer tells Chloe to make a call, everything that happens from that moment on — the live call, the conversation itself — is this team's responsibility.

• Seasoned engineer. Python is our backbone, but you may have worked across Go, Rust, or Type Script. Pick the right tool for the workload rather than retreating to what you know.
• Deeply experienced with email and calendar platforms: IMAP, sync protocols, calendar APIs, and the thousand edge cases of oddly configured enterprise mail servers. This experience makes someone successful on this team fastest.
• Fluent in real‑time and async distributed systems:
  WebRTC, Web Sockets, queues, streaming. Debugged a production incident where latency budgets didn’t hold.
• Opinionated about AI in real‑time workflows. Built or used live transcription, voice agents, or in‑the‑loop AI features. Have a view on what’s ready for production versus what’s still a demo.
• At home in the gnarly bits: telephony providers, codecs, retries, eventual consistency. Drawn to systems where edge cases actually matter. Deep Twilio or similar telephony experience is a big plus.
• Working with AI in day‑to‑day. Use AI tools in your own workflow to ship faster, write tighter code, and reason about unfamiliar parts of the codebase.
• A builder first. Prefer a sloppy v1 in front of fifty customers than spend three weeks on abstractions. Ship.

• Overhaul how Close syncs email and calendars. Our sync engine has run for a decade; we’re making a serious, ground‑up investment in its performance and reliability. Millions of sales emails and calendar events, and when it breaks, customers feel it within ten minutes. You’ll be in the middle of one of the biggest infrastructure rebuilds at Close.
• Take voice agents further into the call. Expand our voice agent capabilities and infrastructure — including custom models tuned for conversational edge cases like voicemail and automated phone‑tree detection (turns out “wait for the beep” is a hard AI problem).
• Solve inbound. Chloe currently makes calls; next she will answer them. An inbound conversation can go anywhere — which raises real questions about specialized agents, a receptionist layer, and seamless call routing between them. Largely unexplored territory.
• Build native scheduling. Core calendar scheduling capabilities inside Close, plus more powerful scheduling for our agents. Various projects landing over the next 6–12 months.
• Design human orchestration of an agentic workforce. Agents create work for humans too — things to review, approve, respond to. Surface what’s happening inside the CRM so each person engages with what actually needs them. A genuinely open product‑engineering problem.
• Push connect rates and answer rates. Phone number pooling, local presence, branded calling, reputation monitoring. Real revenue impact, real telephony plumbing.
• Move our streaming and event substrate forward. Kafka, Redis, pub/sub. The plumbing the rest of the product runs on.

• Python
• Twilio
• WebRTC
• Web Sockets
• AssemblyAI
• Eleven Labs
• Kafka
• Redis
• PostgreSQL
• MongoDB

• Build a house you want to live in — Examine long‑term thinking and action
• No BS — Practice transparency and honesty, especially when it’s hard
• Invest in each other — Build successful relationships with your coworkers and customers
• Discipline equals freedom — Keep your word to yourself and others
• Strive for greatness — Constantly challenge yourself and others