StackOne raises $20m Series A Led by GV (Google Ventures) to reinvent SaaS and AI agent integrations

London, 2025 — StackOne — the next-gen, AI-powered platform fuelling the future of enterprise AI agents and SaaS integrations — has raised $20 million in a Series A round led by GV (Google Ventures). Workday Ventures, XTX Ventures, existing investors Episode 1 and Playfair, and angels from OpenAI, Deepmind, Microsoft and Mulesoft also participated.

The funding, which takes the total raised by StackOne to $24 million, will be used to continue building StackOne’s state-of-the-art tool-calling LLM, invest in R&D, and further expand the number of integrations and depth of actions available in the StackOne platform.

Integrations: From features to table stakes

Software platforms live or die by how well they integrate with other tools — whether it’s an AI recruitment agent sourcing candidates in Workday; a SaaS security platform raising a ticket on ServiceNow; or a BambooHR agent automating onboarding. Integrations are so important, they’re now a top priority for 83% of B2B buyers, yet 71% of SaaS firms still take three weeks or more to launch a single connection meaning engineering teams are losing valuable time and resources, and SaaS firms are losing out on contracts.

StackOne’s founders — Romain Sestier (CEO) and Guillaume Lebedel (CTO) — saw this first-hand during 10+ years of working together at multiple companies, building billion-dollar SaaS products for Google, Oracle and Yieldify. With the rise of AI agents demanding a new kind of integration interface, this challenge is only getting harder and while emerging standards, like Model Context Protocol (MCP), show where the market is heading, they lack the security, depth, and scalability needed for real enterprise use.

StackOne solves all of this by reinventing the way integrations are built — combining a proprietary AI agent and real-time engine to give teams the speed, coverage and reliability to finally connect SaaS and AI agents to the enterprise tech stack.

AI-first and Enterprise-ready

For StackOne, AI isn’t just an add-on, it’s at the heart of everything it does. Normally, developers spend weeks combing through messy enterprise APIs, writing custom logic just to get a single integration to work. StackOne’s proprietary AI agent takes on this heavy lifting. It automatically builds use-cases on top of even the most complex APIs, connecting AI and SaaS tools to their customers’ entire tech stack in a fraction of the time, and with higher accuracy than even the most precise, leading LLMs.

Through the platform, product teams get access to 10,000+ actions on 200+ connectors instantly, from Workday (HRIS) to HubSpot (CRM), Jira (Ticketing), and Okta (IAM). StackOne’s proprietary AI-first, enterprise-ready approach means integrations are secure and up-to-date by default, and all of this frees developers up to focus on core roadmap features and scale without sacrifice.

The new generation of future-proofed integrations

In this way, StackOne represents an entirely new generation of integration platforms. One that will finally fuel global adoption of enterprise AI Agents, and which is purpose-built to scale with even the largest organisations, while being future-proofed to stay at the forefront of AI’s rapid growth. This has seen StackOne become one of the fastest-moving players in the $17.5 billion integration space, having recently surpassed 1 billion API calls, and with customers including Drata, Attensi, Localyze and more across three continents.

Compliance leader Drata recently used the platform to rapidly launch 100 integrations, while management development leader Mindtools delivered a Workday integration in record time, securing a major contract.

For today and tomorrow

StackOne is also building a growing AI developer community, including its own AI Demo Days that bring together researchers, builders, and infrastructure teams, and its own open-source contributions. This is part of StackOne’s broader mission to create not just the best integration platform, but the go-to hub for the people building the future of AI-powered software.

Romain Sestier, Co-founder and CEO: “StackOne doesn’t just reinvent integration platforms — we deliver depth, accuracy and security by default.”

Guillaume Lebedel, Co-founder and CTO: “Integrations are table stakes for B2B SaaS success, especially for AI agents. Standards like MCP lack the enterprise-grade security and scale needed for real business use.”

Luna Schmid, Partner at GV: “Romain and Guillaume aren’t building another SaaS integration platform. They’re creating infrastructure for modern software and the AI agent ecosystem.”

Barbry McGann, Managing Director and SVP at Workday Ventures: “StackOne integrates deeply with complex enterprise systems, and their focus on agent interoperability unlocks more powerful use cases for customers.”

About StackOne

StackOne is the integration infrastructure for AI agents taking actions on B2B SaaS. The platform helps AI agents connect to any enterprise application and take fast, accurate, and secure action. With 200+ prebuilt integrations and 10,000+ out-of-the-box AI actions, teams can ship in hours. StackOne’s AI Builder lets developers extend or create any connector or action. Unlike unified APIs that break for agents, StackOne’s bidirectional, real-time platform stores no data by default, is fully compliant, and provides managed auth, AI execution, and permissions to ensure low-token execution and safe production operations. For more information, please visit: stackone.com.