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StackOne

AI · London, United Kingdom · Founded 2023

Accelerate your SaaS growth with our unified API solution for HRIS, ATS, and CRM MoreLess

StackOne is a dynamic startup that specializes in providing a unified API (Application Programming Interface) platform designed to simplify and streamline the integration process for businesses. The company operates in the technology and software market, focusing on clients who need to connect various software tools and systems seamlessly. These clients typically include businesses that use multiple software solutions for HR (Human Resources), CRM (Customer Relationship Management), and marketing, among others.

StackOne's business model revolves around offering a single, unified API that allows businesses to integrate different software tools without the usual complexities and security concerns. This unified API supports a wide range of integrations, including popular tools like HaileyHR, BreatheHR, HR Cloud, Pipedrive, and Greenhouse. Recently, they have also introduced a marketing API with initial support for Klaviyo, a marketing automation platform.

The company makes money by charging businesses for access to its API platform. This can be through subscription models, where clients pay a recurring fee to use the service, or through usage-based pricing, where clients are charged based on the number of API calls or the volume of data processed. By providing a reliable and secure integration solution, StackOne helps businesses save time and resources, allowing them to focus on their core activities.

In summary, StackOne is a tech startup that offers a unified API platform to simplify software integrations for businesses, particularly in HR, CRM, and marketing. It operates on a subscription or usage-based revenue model, ensuring secure and efficient connections between various software tools.

Keywords: Unified API, Software Integration, HRIS, CRM, Marketing API, Klaviyo, Subscription Model, Usage-Based Pricing, Secure Integrations, Tech Startup.

Company overview

StackOne company information

The essential company record, classifications and operating signals in one place.

Status
Operational
Founded
2023
Headquarters
London, United Kingdom
Employees
54
Open positions
5
Dealroom signal
79.7
client focusb2btechnologyArtificial Intelligencebusiness modelSaaSsectorDeveloper ToolssectorAPIsectorCore AIsectorB2B IntegrationssectorMLopssectorAI Model Deployment and MonitoringsectorAI Agentssectoruk is8 digital and technologiesindustryEnterprise Software

Valuation & funding

StackOne funding history

Company financing events and reported valuations.

Deal typeDateAmountValuationInvestorsSource
SERIES AEquity / VC May 2025 $20M $80M Playfair Capital · Workday Ventures · GV · Episode 1 Ventures
SEEDEquity / VC Mar 2024 $3.6M $14M Playfair Capital · Sequoia · Charlie Songhurst · Portfolio Ventures
Showing 2 recorded eventsUnlock the complete deal history →

Financials

Workforce over time

Available workforce history. Financial fields without reported data are omitted.

YearEmployees
2026 56
2025 57
2024 33
Company filings, research estimates and Dealroom dataOpen the full financial model →

Growth signals

StackOne website traffic

Latest recorded traffic for StackOne is 34K monthly website visits, up 41.7% over the last three months. StackOne's team declined 5.3% over the past year.

Latest monthly visits34K 3-month web change+41.7% 1-year team growth-5.3%
Monthly website visits30 observations · Feb 2024–Jul 2026
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Comparisons

StackOne compared with similar companies

Dealroom’s weighted taxonomy model identifies the closest operating peers. Company identity and context stay open; selected comparison metrics preview what is available in the platform.

Showing 8 of the closest matchesCompare every metric →

Talent graph

StackOne's talent

Book a demo to see the people
Team profiled 15 named & role-tagged
Founders Hidden — book a demo/100 quality score
Key operators 3 quality Hidden — book a demo/100
Potential founders Hidden — book a demo likely future founders
Startup mafia Hidden — book a demo alumni-founded startups
Talent movements Hidden — book a demo in · Hidden — book a demo out past 12 months

Source: Dealroom Talent Intelligence.

Investors

15 investors on StackOne's cap table

Sourced from Dealroom's funding and investor records. Investor profile links are shown where available.

Seed 5 investors entered at this stage
Episode 1 Ventures
Playfair Capital
Sequoia
Charlie Songhurst
Portfolio Ventures
Series A 3 investors entered at this stage
GV
Workday Ventures
XTX Ventures
Other known 7 additional known investors
Edward Lando
Grow London
Neil Andrew
Oliver Molander
Richard Hadler
Rockman Law
Timoteo Rouchon

Global footprint

Where StackOne has talent and traffic

Workforce by country
10 countries with
team presence
🇬🇧 United Kingdom68.2%
🇺🇸 United States13.6%
🇫🇷 France2.3%
🇬🇭 Ghana2.3%
🇱🇺 Luxembourg2.3%
Top 5 of 10 shown

In the news

Latest news about StackOne

Recent press, funding announcements, and product moves mentioning StackOne — open to read from the original sources.

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Market sentiment

What the market is saying about StackOne

An AI-synthesized read of the highest-engagement posts about StackOne on X over the past 7 days. We rank by likes & retweets, ignore corporate channels, and surface the themes that broke out from real people.

Reading the room on X — pulling top posts and synthesizing themes…

Source: X recent search ranked by engagement (likes + retweets) · Synthesis by Claude · Cached for 1 hour

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