Senior Full-Stack Engineer – Founding Team – Vertical AI B2B SaaS

About Antai Ventures

Antai Ventures is a Barcelona-based venture studio with presence across Southern Europe and Latin America. Since 2012, we have co-founded 35+ companies including Glovo, Wallapop, Piper, PlatanoMelon, and Vitaance. Our ventures have raised over $1.5B in funding, generated more than $3B in shareholder value, and currently employ more than 3,000 people.

The Company & Vision

You'll join the founding team of one of our portfolio companies — a B2B SaaS platform that helps service companies manage complex, day-to-day operations of their distributed frontline workforce. The platform powers scheduling, real-time coordination, coverage resolution, time tracking, and client communication — all powered by an AI agent capable of making phone calls, contacting workers, and taking autonomous action to keep operations running smoothly.

The vision is ambitious: build the operating system for an entire industry, starting with day-to-day operations, then expanding into deeper integrations across finance, HR, and beyond. AI is embedded from day one as a core capability, not bolted on as an afterthought.

The Role

As one of the first engineers on a small, high-ownership team, you'll build a product from the ground up. This is not a ticket-driven role. You will research customer problems, craft detailed specs, design solutions, write code, and ship features end-to-end. You'll work directly with founders and bring strong judgment about what to build, how to build it, and when to keep things simple.

We need someone genuinely full-stack: comfortable across backend, database, frontend, mobile (web-based via Capacitor), and cloud infrastructure. You don't need expertise in every layer, but you need confidence and curiosity to work through problems across the entire stack, learn what's needed, and find the right solutions.

Key Responsibilities

• Study customer problems deeply and translate insights into detailed functional and technical specs, then turn those specs into working software
• Design and build core backend systems powering workforce scheduling, real-time coordination, and operational workflows
• Develop frontend and mobile interfaces that make complex operations intuitive for end users
• Architect cloud infrastructure and databases that scale reliably
• Collaborate with founders on product strategy and technical direction
• Own end-to-end feature delivery from conception to production

About You

• Strong full-stack engineering fundamentals across backend, frontend, databases, and infrastructure
• Proven experience shipping products end-to-end in early-stage environments
• Comfortable with ambiguity and able to make good technical decisions with incomplete information
• Customer-obsessed: you understand the value of deeply understanding user problems
• Proficient English required; basic Spanish is a plus

What We Offer

• Compensation: €50–70K + equity
• Location: Barcelona, hybrid (some office days)
• Employment: Full-time
• Impact: Join a founding team at a venture studio with a proven track record of scaling companies to billion-dollar valuations