London-based StackOne has raised $20M (nearly €17.67M) in a Series A funding round. This brings the company’s total raised capital to $24M.
The round was led by GV (Google Ventures). Workday Ventures, XTX Ventures, Episode 1, Playfair, and individual investors from OpenAI, DeepMind, Microsoft, and Mulesoft also joined the round.
Luna Schmid, Partner at GV, says, “What impressed us most about StackOne is its ambition and clarity. Romain and Guillaume aren’t building just another SaaS integration platform. They’re creating infrastructure that modern software and the entire AI agent ecosystem can rely on. The depth of secure integrations, the pace of delivery, and the team’s foresight into AI’s future uniquely position StackOne to redefine this category.”
The company will use the funds to develop its tool-calling language model, invest in research and development, and increase the number of integrations and available actions on its platform.
Fueling innovation by connecting software
StackOne is addressing integration challenges faced by software platforms, which depend on connections with other tools to operate.
Tasks such as recruitment, security alerts, and HR processes often rely on integrations between AI agents and enterprise systems. These connections are a top concern for 83 per cent of B2B buyers, but 71 per cent of SaaS companies still take over three weeks to launch a single integration, resulting in delays and lost opportunities.
Founders Romain Sestier and Guillaume Lebedel encountered these issues over a decade of building SaaS products at companies like Google, Oracle, and Yieldify.
As AI agents become more common, the need for new integration methods is increasing. Existing standards, such as Model Context Protocol, provide direction but fall short in areas required for enterprise use.
StackOne responds to this by introducing a new integration method using a proprietary AI agent and real-time engine. This approach helps teams link SaaS products and AI agents with enterprise systems more efficiently.
Co-founder, Romain Sestier, says, “For over a decade, Guillaume and I have felt the acute pain of integrations. We’d see teams burn months rebuilding or refusing requests and nothing on the market eased this pain. So we, alongside a super-talented and passionate team, built it ourselves.”
“StackOne doesn’t just reinvent how integration platforms can and should be built – with depth, accuracy and security by default – but we believe AI agents are the missing piece in finally delivering enterprise-grade integrations at scale.”
“It’s the platform we’d always dreamed of, built for the AI future of SaaS, and it’s a vision shared by the whole team. This shared experience has shaped a culture of innovation, collaboration and deep care for the product we’re building and it shows.”
Currently, the platform provides access to over 3,000 actions across 200+ connectors, streamlining integrations across various systems such as HR, CRM, ticketing, and identity access management. This approach ensures that integrations are secure and up-to-date, allowing developers to focus on scaling and product development.
Building an AI developer community
StackOne is also developing an AI developer community through initiatives like AI Demo Days, which bring together researchers, builders, and infrastructure teams, and by contributing to open-source projects.
This effort supports StackOne’s goal of becoming a central hub for those working on AI-powered software integration.
Co-founder and CTO, Guillaume Lebedel, says, “Integrations are now table stakes for winning and keeping customers in B2B SaaS, especially for the ever-growing swathe of AI agents.”
“You only need to look at the rise of standards like Model Context Protocol (MCP) to see the demand, but these protocols just aren’t fit for enterprise use by themselves – they’re a small piece of the puzzle. They lack security, accuracy and scale. They don’t work with multi-tenant systems, they’re too restrictive for the complex needs of big business, and they don’t go deep enough.”
“StackOne solves all of this in a single layer; one that marks the birth of a new generation of integrations platform for an AI-first world.”
Barbry McGann, Managing Director and SVP at Workday Ventures, adds, “We’ve been impressed by how quickly and deeply StackOne integrates with complex enterprise systems – and now, with their focus on agent-to-agent interoperability, they’re unlocking even more powerful use cases for customers.”
“In a space where speed and scale often trade off with reliability, compliance, and functionality, StackOne delivers all of the above in a universal layer – without compromise.”
