CTO & Co-Founder - Agentic AI (LegalTech)

Antai Ventures

🌍 ABOUT ANTAI VENTURES Antai Ventures is a Barcelona-based venture studio with presence across Southern Europe and LatAm. We partner-up and invest in the best co-founders to build global companies willing to disrupt multi-billion dollar industries. Since 2012 we have co-founded +30 companies including Glovo, Wallapop, PlatanoMelon, and Piper. Our ventures have raised more than $1.5B in funding, have generated more than $3B in shareholders value and currently employ more than 3000 people. 💡ABOUT THE VENTURE We are building an AI-native platform for the real estate sector in Spain — one of the most fragmented, relationship-driven, and underdigitised industries in Southern Europe. We have a validated product thesis, a clear go-to-market, and we're now looking for a co-founder & CTO to build it. 🎯 WHAT YOU’LL DO * Build, launch and scale a disruptive product from scratch. * Own the technical architecture — define the stack, set the engineering standards, and make the hard trade-offs between speed and scalability from day one. * Design and implement a multi-agent orchestration layer — persistent state management, agent-to-agent handoffs, tool-calling pipelines, and context windows that don't collapse under real usage. * Build and maintain LLM-powered workflows in production. * Integrate third-party infrastructure (voice providers, CRMs, payment and signing APIs, document verification) into a coherent, maintainable system. * Ship code daily — from prototype to production, you are hands-on throughout. * Drive a culture of excellence through continuous delivery, rapid experimentation, and customer-obsessed iteration. 🔍 WHAT WE’RE LOOKING FOR * Proven track record as a hands-on engineer, tech lead, or CTO in an early-stage environment. * Hands-on builder. You prototype fast and turn ideas into working features in days, not weeks. * Practical AI experience. You have built production systems with LLMs — agent orchestration, multi-agent workflows, conversational AI — and know what actually works outside a demo. * Architectural thinking. You design systems that are simple enough to ship fast today and solid enough to scale tomorrow. * Ownership mindset. You take responsibility for outcomes and think long-term about product and company value. * Clear communicator. You can explain technical trade-offs to engineers and non-technical co-founders alike. * Fluency in Spanish and English. 🤝 WHAT WE OFFER * Day-1 founding seat. Join an ambitious venture from the ground up, with a validated concept and Antai's full backing. * Significant equity. Own a meaningful stake in the venture, plus optional carry in other Antai portfolio companies. * Full-stack operator support. Access Antai's expert teams in Product, Engineering, Design, GTM, Legal, Talent, and Fundraising whenever you need them. * Founder community and investors. Join a tight network of serial entrepreneurs and top-tier backers who have scaled category leaders. * Based in Barcelona, hybrid.

fonio

We build AI phone assistants for small and medium-sized businesses – so they never miss a call again and can focus on what matters most. Our AI answers every call automatically. But voice is just the beginning. Our vision is to build the first fully automated CRM system in the world. 8,000+ customers. >€5M ARR. ~30% monthly growth. Target by EOY: €30M. We live ownership. You own your projects and tasks end-to-end. No politics, few meetings, direct feedback. At fonio, you'll build alongside the smartest and most ambitious people around. Apply now and become part of one of Europe's most insane growth stories! YOUR ROLE As a Forward Deployment Engineer for our Spanish and Italian markets, you work directly at the intersection of product and customer setups. You capture requirements, translate them into robust implementations, and take fonio live at customers – including integrations, automations, and ongoing optimization. You work closely with Product/Engineering and Go-to-Market, making sure deployments are fast, stable, and repeatable across both the Spanish and Italian markets. This is a Barcelona-based role, ideally suited to someone who can operate natively in both Spanish and Italian. WHAT YOU'LL DO * Capture customer requirements and translate them into concrete implementation plans * Build and roll out fonio setups in production: workflows, logic, prompts, guardrails * Implement integrations with third-party systems (APIs, webhooks, CRM, calendar, ticketing, etc.) * Develop smaller features and glue code to cleanly map customer cases * Debug under production conditions: calls, flows, edge cases, fast fixes * Build reusable templates and deployment playbooks to make setups scalable * Deliver product feedback: bring pain points and feature gaps to the team, prioritized and concrete WHO WE'RE LOOKING FOR * Solid coding skills: you can implement independently, not just configure * Strong understanding of AI systems and LLMs (prompting, tool-use, RAG, failure modes) * Workflow thinking: translate complex processes into robust, testable flows * Experience with APIs, webhooks, auth, and common integration patterns * Cloud fundamentals: deployments, observability, debugging in production * Highly pragmatic working style: ship fast, make it stable, iterate * Bonus: Voice/Telephony, n8n, TypeScript/Python, SQL, monitoring/tracing, GDPR * Spanish and Italian at native or near-native level & English fluent WHAT WE OFFER * Competitive salary: €65,000–€95,000 per year * Barcelona-based role, with relocation to Vienna for onboarding; we also have one of the coolest offices in Vienna's 7th district (lunch & dinner included) * 100% Focus Time (no regular meetings) * Unlimited budget when the ROI is right * Extreme speed (we ship almost daily) * Thousands of enthusiastic customers building the product together with us HIRING PROCESS * 15 min intro * 30 min deep dive with CTO & Co-Founder Matthias * 90 min technical interview with case study / live coding * 20 min culture fit with both founders

Tandem Health

BUILD SOMETHING MONUMENTAL FOR HEALTHCARE! At Tandem Health we’re reimagining healthcare by putting clinicians first. Our platform - designed by clinicians, for clinicians - is built on deep insight into real-world pain points, with intuitive medical notes and workflows that truly support patient care. We’re a fast-scaling health-tech company backed by top investors and expanding globally. We move fast, stay curious, and believe building something that matters starts with an extraordinary team. If you're passionate about impact and innovation, we'd love to meet you! ABOUT THE ROLE We’re looking for an exceptional Senior AI Engineer to join us in building the future of healthcare in Europe. This is not a traditional ML role. We’re looking for someone who has spent the last few years deeply immersed in building real-world, LLM-native products - someone who has moved beyond prototypes and understands what it takes to ship fast, reliable, production-grade AI systems that users depend on every day. Today, our AI products are already used daily by thousands of healthcare professionals across Europe. Our AI scribe is live in production at significant scale, and we’re now expanding far beyond documentation into a broader suite of AI-native workflows and products across the healthcare experience. You’ll join a small, highly ambitious team building some of the most advanced applied AI systems in European healthcare. We believe AI will fundamentally reshape healthcare over the coming decade, and we’re building products that meaningfully improve how care is delivered at scale. This role comes with substantial ownership, not only over technical execution, but also over shaping new AI initiatives, product directions, and how AI gets deployed across the company. We’re still early enough that the right person will have enormous impact on both the product and the organization, while working alongside an unusually strong team of engineers, builders, and operators. This role is ideal for someone currently building AI-heavy products at a startup or fast-moving tech company, and who wants to work even closer to the frontier of applied AI. WHAT YOU WILL DO * Build and scale deeply integrated LLM-powered product experiences used daily by healthcare professionals across Europe * Lead new AI initiatives from concept to production, helping define both technical direction and product strategy * Design robust systems around prompting, orchestration, evaluation, retrieval, agents, speech, and model infrastructure * Own projects end-to-end - from early product thinking and architecture decisions to deployment and iteration in production * Work closely with product, design, and engineering to create AI experiences that feel magical while remaining reliable and practical * Continuously evaluate and integrate new models, tooling, and infrastructure as the ecosystem evolves * Improve performance, latency, reliability, and cost-efficiency across our AI stack * Help shape how we work with AI across the company as we continue scaling our platform and team WHAT YOU BRING * 5+ years of engineering experience, with at least 2–4 years spent primarily building and shipping LLM-powered products * Strong hands-on experience applying modern LLMs in production environments - not just experimentation or research * Experience building agentic workflows or complex multi-step LLM systems * Experience leading technical initiatives or owning major AI product areas with high autonomy * Experience working with evaluation pipelines, model monitoring, or AI reliability systems * A strong product mindset and intuition for building AI experiences that create real user value * Experience operating in fast-moving startup environments with high ownership and ambiguity * Strong software engineering fundamentals and ability to build high-quality systems end-to-end * Experience with technologies such as Python, TypeScript, React, Kubernetes, or similar modern tooling * Deep curiosity about the rapidly evolving AI landscape, and excitement to stay at the frontier of applied AI * A collaborative, low-ego approach and desire to work with exceptionally talented teammates Bonus Points * Experience with speech-to-text, voice AI, or multimodal models * Experience in healthcare or other regulated industries * Experience with fine-tuning and training LLMs LOCATION We believe the best ideas happen when we’re together. This role is based in our vibrant HQ in the Epicenter building in the heart of Stockholm where you will work primarily from our office to collaborate, connect, and build our culture. HOW TO APPLY We adopt a continuous selection process, so please make sure to apply with your CV in English. Our interview process consists of 4 stages: 1. Screening interview with Talent Acquisition 2. Technical interviews with some of our Engineering team 3. System Design Interview at our office - Join us in the Stockholm office for a lunch and a Product focused System Design interview to experience our culture firsthand, collaborate with our team, and see how you work in action. 4. Follow-up interview with our CTO & Co-Founder We're currently in the middle of vacation season, which means it may take us a little longer to review applications and get back to you. Thanks for your patience - we're looking forward to reading your application! BENEFITS * Competitive salary & company stock options * 30 days/year of paid vacation * 5,000 SEK wellness allowance (friskvårdsbidrag) plus an additional 6,000 SEK yearly to spend on other health related initiatives * Generous Parental leave top-up for new parents * Private Medical Insurance to stay healthy * Mental health support through our partner Mindler * Pension program * Social and team-building activities (off-sites, after works, winter/summer parties) * An opportunity to make a real positive impact in the world of healthcare * Work with some of the best minds in AI, healthcare, and engineering. We review our benefits packages on a regular basis and might modify our benefits from time to time.   CULTURE AT TANDEM At Tandem, we move fast, think big, and take ownership. We're a high-performing, diverse team with a shared drive to change the future of healthcare - and we’re just getting started. Our culture is built on action, ambition, and learning. You'll be trusted to take the lead, challenge yourself, and make an impact from day one. We believe real growth happens when you're stretched, supported, and surrounded by smart, passionate teammates who want to win together. Even though we’re spread across countries, we come together often in Sweden for team meetings, social events, and offsites - blending global reach with real human connection. We hire for talent, potential, and attitude - valuing different backgrounds and fresh perspectives. Great ideas come from everywhere, and we’re building a team that reflects the world we want to change. Tandem handles sensitive patient data and will conduct a background check before hiring any candidate.