Senior Full Stack / Backend Engineer

VOICEB.ai; España; On-site; PHP 3,196,022 - 4,616,477; Full time

Benefits offered by this job

Fully remote work

Access to coworking space

Market-rate salary + equity compensation

Job summary

VOICEB.ai is seeking a fully remote Backend Engineer based in Spain to design and build core systems for their autonomous voice agent platform. The role requires over 5 years of experience in backend systems, strong expertise in Twilio and voice infrastructure, and capability in full stack development. The engineer will work directly with the CTO and contribute to key architecture decisions. VoiceB.ai offers market-rate salary and equity compensation after the first year, and a small, senior team atmosphere for impactful contributions.

Qualifications

• 5+ years of experience building production backend systems.
• Hands-on experience with Twilio, SIP, WebRTC, RTP, and real-time audio.
• Experience with LLMs and AI/ML systems in production.
• Capable of full stack development as needed.
• Strong understanding of latency, concurrency, and reliability.

Responsibilities

• Design and build core systems for the autonomous voice agent platform.
• Own the voice infrastructure layer including Twilio and WebRTC.
• Shipping full stack when necessary.
• Work closely with the CTO and senior engineering team.
• Integrate with Salesforce, HubSpot, and enterprise CRMs.
• Contribute to architecture decisions for voice AI.

Skills

Building production backend systems (Node.js, Python, Go)

Twilio and voice infrastructure

Integrating LLMs, STT/TTS pipelines

Full stack capability

Strong systems thinking

Advanced English (C1+)

Ownership mindset

Job description

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.