Full Stack / Backend Engineer

Voiceb
Cillorigo de Liébana, Spain
2 days ago

Role details

Contract type
Permanent contract
Employment type
Full-time (> 32 hours)
Working hours
Regular working hours
Languages
English
Experience level
Senior

Job location

Remote
Cillorigo de Liébana, Spain

Tech stack

Artificial Intelligence
Codecs
Python
Node.js
Salesforce
Systems Integration
Twilio
WebRTC
Real-Time Transport Protocol
Chatbots
Large Language Models
Concurrency
Backend
Build Management
Low Latency
Machine Learning Operations
Front End Software Development
Hubspot
Go

Job description

Senior Full Stack / Backend Engineer - Voice & AI Aumente sus posibilidades de llegar a la fase de entrevista leyendo la descripción completa del puesto y enviando su solicitud sin demora. VoiceB | Fully Remote (Spain) | Engineering

We're VoiceB. We're building the autonomous AI voice sales agent that's automating the last undigitized sales channel: the phone call. Top enterprise brands across telco, banking, insurance, energy and automotive are already using our platform to handle inbound B2C and B2B sales conversations end-to-end - qualifying, pitching, and closing without human agents. We're profitable, growing fast, and just getting started. Now we're hiring a Senior Engineer to help us scale the core platform that powers it all.

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.

Requirements

  • 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 *****, SOC 2).

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