Head of Customer Success

Callstack is a cross-platform and AI-native technology company working with some of the world’s leading brands to build better digital products and services. We’re known for pushing the React Native ecosystem forward - from co-founding the React Foundation and contributing to Open Source to organizing React Universe Conf, Agent Conf, and community events around the world. But Callstack is built by more than great engineers. Behind our technology is a team of people shaping how we grow, work with clients, build our brand, and create new opportunities. We give people the space to take ownership, bring ideas to the table, and make a real impact on how the company evolves. As Callstack grows into new technologies, markets, and ways of working, you’ll have the opportunity to grow with it. Join us and take the next step with Callstack! We are looking for an experienced Head of Customer Success who will own and scale a portfolio of 150–200M PLN in annual revenue, lead a team of 3–5 Account Managers, and act as a bridge between business value and technical innovation. The Head of Customer Success is responsible for maintaining strong client relationships, ensuring successful service delivery, and driving revenue growth through upselling, cross-selling, strategic account development, and team leadership. This role carries direct P&L accountability with ambitious year-over-year growth targets. You will work directly with the Head of Engineering to articulate deeply technical business value propositions and position Callstack as a strategic technology & business partner - not a delivery vendor. As a Head of Customer Success you will: - Own the full revenue target for a 150 - 200M PLN portfolio with ambitious YoY growth goals. You are the single point of accountability for top-line performance. - Drive upsells, account expansions, cross-sells, and end-to-end renewals to ensure consistent revenue growth across the entire portfolio. - Build and execute mid- and long-term key account plans, including stakeholder mapping, competitive positioning, and expanding into new client divisions to unlock incremental revenue. - Lead pricing strategy, contract negotiations, and commercial deal structuring for the largest and most complex engagements. - Develop account strategies and roadmaps to strengthen long-term partnerships and maximize lifetime value. - Personally own relationships with top-tier accounts. Lead regular executive-level 1:1s with key stakeholders and plan onsite visits to deepen partnerships. - Build and maintain long-term relationships with key client stakeholders across all levels of the organization. - Act as a bridge between clients and R&D, sharing technology trends and innovation insights to position Callstack as a strategic partner. - Partner closely with the Head of Engineering to develop technical value propositions that elevate conversations from operational delivery to strategic transformation. - Lead, coach, and develop a team of 3 - 5 Account Managers. Set performance expectations, run deal reviews, and build a high-performing commercial culture. - Establish scalable account management processes, playbooks, and reporting cadences that drive consistency and predictability across the team. - Monitor client financial situation monthly, map potential risks to current and future revenue, and execute churn prevention measures. - Manage sales forecasting, pipeline reporting, account reporting, legal contracts, and the acquisition of case study approvals. - Connect various client initiatives by providing cross-project context, market intelligence, and industry-level positioning. - Drive referrals and stakeholder introductions to expand account footprint organically. - Travel up to 25% of working time, including international travel (US, Europe, Asia), to build and deepen relationships with key clients and represent Callstack at industry events.