London-based deeptech startup StackOne has secured €17.6 million ($20 million) in a Series A funding round led by GV (formerly Google Ventures), with participation from Workday Ventures, XTX Ventures, Episode 1, Playfair, and angel investors from OpenAI, DeepMind, and Microsoft.
The raise brings StackOne’s total funding to $24 million.
The startup is building what it calls the foundational infrastructure for integrating AI agents and SaaS products into enterprise systems — solving a growing pain point in software interoperability.
Addressing the SaaS integration bottleneck
Founded by former Google, Oracle, and Yieldify product veterans Romain Sestier and Guillaume Lebedel, StackOne tackles the slow, error-prone integration processes common in B2B software. According to the company, over 70% of SaaS firms still take more than three weeks to launch a single integration — a major friction point as AI-powered tools proliferate.
StackOne’s platform already supports over 3,000 actions across more than 200 connectors, covering HR, CRM, identity, and ticketing systems. It uses a proprietary real-time engine and tool-calling language model to enable fast, accurate, and secure integration with enterprise software.
Sestier said, “We saw teams burning months rebuilding integrations or declining them entirely. So we built the platform we always wished we had — one built for the AI future of SaaS.”
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Unlocking AI-first workflows
With the rise of agent-based AI systems, StackOne positions itself as the connective tissue between AI tools and complex enterprise environments. Existing standards like Model Context Protocol (MCP), the company argues, lack the depth, security, and compatibility needed at scale.
“Our platform marks the birth of a new generation of integration infrastructure for an AI-first world,” said CTO Guillaume Lebedel.
The funding will be used to further develop StackOne’s real-time integration engine, scale its tool-calling AI models, and grow its library of connectors.
Building a community and platform for AI builders
Beyond the product, the company is also fostering an AI developer ecosystem through its AI Demo Days and open-source contributions. These initiatives aim to make the platform a hub for developers creating AI-native software products that require robust and flexible integrations.
Barbry McGann, Managing Director at Workday Ventures, said, “StackOne brings enterprise-grade performance, compliance, and reliability to the integration space — critical as AI reshapes the software stack.”
With this latest funding and strong traction in enterprise markets, StackOne is positioning itself to become a core infrastructure provider for the next wave of AI-first enterprise software.
