Senior Full Stack / Backend Engineer

VoiceB | Fully Remote (Spain) | Engineering

What you'll do

• Design and build core systems behind our autonomous voice agent platform — real-time voice pipelines, LLM orchestration, telephony integrations and CRM connectors.
• Own the voice infrastructure layer: Twilio, SIP trunks, WebRTC, and the real-time audio plumbing that makes a sub-second AI conversation feel human.
• Ship full stack when needed — backend is your home, but you're comfortable touching the frontend to deliver end-to-end.
• Work directly with our CTO and a small, senior engineering team where every line of code matters.
• Integrate with Salesforce, HubSpot, ad platforms (Google, Meta) and enterprise CRMs.
• Contribute to architecture decisions that will define how voice AI scales over the next 5 years.

What we're looking for

• 5+ years building production backend systems (Node.js, Python, Go, or similar).
• Hands‑on experience with Twilio and voice infrastructure — SIP, WebRTC, RTP, codecs, real-time audio. This is non-negotiable.
• Experience integrating and working with LLMs, STT/TTS pipelines, or AI/ML systems in production.
• Full stack capability — you can move across the stack when the product needs it.
• Strong systems thinking: latency, concurrency, reliability at scale.
• Advanced English (C1+). You'll work daily with enterprise customers and a global team.
• Hard worker, ownership mindset, comfortable in a high‑velocity startup environment.

Nice to have

• Experience with conversational AI, IVR systems, or contact center platforms.
• Background in CRM integrations (Salesforce, HubSpot).
• Previous exposure to enterprise‑grade compliance (GDPR, ISO 27001, SOC 2).

What we offer

• Fully remote within Spain, with access to a coworking space if you want one.
• Reporting directly to Luis Miguel, our CTO.
• Market‑rate salary + equity compensation after your first year.
• A small, senior team working with some of the largest brands in Europe.
• Real ownership over critical product areas — no layers, no politics.
• A category‑defining product at a category‑defining moment for AI.

Location

Spain (fully remote)

If you want to build the infrastructure that's automating the world's last analog sales channel — and do it alongside a team that ships — let's talk.