Senior Full Stack Engineer — AI Voice Platform - zaragoza
Summary
Senior full stack engineer building VOICEB.ai's autonomous AI voice-agent platform: backend services, APIs, integrations (Salesforce, HubSpot, Twilio, SIP/WebRTC) and internal tooling. Remote within Spain, owning features end to end on a small team with the CTO, using a modern JS/TS stack (React/Node) on AWS/GCP.
About VoiceB
We build autonomous AI voice agents that close and qualify sales for large B2C enterprises — telcos, energy providers, insurers, banks. Our agents already run live inside companies like Vodafone España and Holaluz, and we're mid-rollout across an 8-market European deployment with Alpega/Teleroute. We're a small team moving fast, and we're building the commercial engine to match the product.
The role
We're looking for a senior full stack engineer to join a small, high-ownership engineering team building the core VoiceB platform — the systems behind SuperVoice, SuperQualification, Memory, and our outcome tracking. This is a remote role for someone based in Spain, working closely with our CTO and the rest of engineering.
What you'll do
- Build and ship features across the platform: backend services, APIs, third-party integrations (Salesforce, HubSpot, Twilio, SIP/WebRTC), and internal tooling
- Own features end to end — design, build, test, deploy, monitor
- Partner directly with the CTO and founders on architecture decisions as the platform scales
- Contribute to security and compliance hardening for enterprise clients
What we're looking for
- 4+ years of full stack experience, comfortable owning features end to end on a small, fast-moving team
- Strong in a modern JS/TS stack (React/Node or similar); comfortable with cloud infrastructure (AWS/GCP)
- Based in Spain, fully remote, able to overlap with Barcelona working hours
- Product-minded — you care about what gets built, not just how
Nice to have
- Experience with real-time or telephony systems (SIP, WebRTC, Twilio)
- Experience integrating LLMs or other AI/voice tooling into production systems
- Early-stage startup experience
What we offer
- Competitive salary + equity
- Fully remote (Spain-based)
- Direct influence over the architecture of a product still being defined
We're hiring deliberately, not urgently — we'd rather find the right person than fill the seat fast. If this sounds like your kind of problem, we'd love to hear from you.