It won’t make anyone choke on their gluhwein to hear that five of the 10 fastest-growing European startups this year, by headcount, are working on AI.
Some of the names on this list — much-hyped AI startups Mistral and Aleph Alpha — are now pretty well-known, but others have kept more under-the-radar, despite scaling up fast.
From AI-first legaltech platforms to nuclear fusion powerhouses and smart energy innovators, these startups are growing rapidly and redefining their industries — and they’re attracting top talent from companies like Tesla, Meta, and Google X.
Using Dealroom data, we focused on companies with at least $30m in funding and a minimum of 50 employees to ensure results weren’t skewed by early-stage hiring sprees.
Here are the 10 European startups which have seen the biggest growth in their teams over the last 12 months.
1/ Nscale
HQ: London, United Kingdom
Founded: 2023
Headcount growth over the last 12 months: 757% to 60 employees in December
Founded by serial entrepreneur Josh Payne — also the founder of Arkon Energy, a London-based data center infrastructure company, and cofounder of the $357m NASDAQ-listed battery metals SPAC, Battery Future Acquisition Corp — Nscale is designing AI-ready data centres with advanced direct liquid cooling technology to support hyperscalers and LLM platforms. Through vertical integration, Nscale maintains full control over power supply and capacity, enabling it to deliver AI-optimised superclusters. With plans to deploy 350,000 GPUs by 2027, the company says it is set to provide a 10% cost advantage over competitors.
2/ Mistral AI
HQ: Paris, France
Founded: 2023
Headcount growth over the last 12 months: 402% to 206 employees in December
Mistral AI, founded by ex-Meta and DeepMind researchers Arthur Mensch, Guillaume Lample and Timothée Lacroix, is building open-source large-language models to rival US giants like OpenAI. Launched just 18 months ago, the startup released its first flagship product, Mistral Large, in February — a commercial LLM accessible via a cloud-based API, offering developers flexible, open-source tools for their applications.
Sifted analysis of Mistral’s team found that two-thirds of the company work in science and engineering roles, while a fifth are in business and sales.
3/ Mylight150
HQ: Jonage, France
Founded: 2014
Headcount growth over the last 12 months: 353% to 213 employees in December
Operating in France, Spain, Switzerland and Romania, mylight150 provides smart solar energy systems for homes and businesses, including solar panels, energy management systems and virtual batteries. Following its €100m Series B in November 2023 Eiffel Investment Group, Azora Capital and Andera Partners, it scaled rapidly, completing over 30,000 installations in France alone. Mylight150 says it helps users cut energy costs by up to 50%.
4/ Lawhive
HQ: London, United Kingdom
Founded: 2021
Headcount growth over the last 12 months: 252% to 74 employees in November
UK-based Lawhive is bringing AI to legaltech, offering workflow tools for compliance and payments to lawyers specialising in consumer and small business law. Its platform doubles as a client-lawyer matchmaking marketplace, with lawyers paying a fee based on their billed services. It raised $40m in a Series A led by Google Ventures in December.
5/ Apron
HQ: London, United Kingdom
Founded: 2022
Headcount growth over the last 12 months: 194% to 53 employees in November
Founded by ex-Revolut product lead Bogdan Uzbekov, Apron is building an all-in-one financial platform for small businesses of up to 100 employees. Its platform consolidates invoices, enables instant payment reconciliation with accounting systems and plans to introduce expense cards and tools for seamless supplier interactions. It raised a $30m Series B led by Zinal Growth, the VC firm founded by Checkout founder Guillaume Pousaz, in September.
6/ Vespa
HQ: Trondheim, Norway
Founded: 2005
Headcount growth over the last 12 months: 194% to 53 employees in December
Vespa.ai, a spinout from Yahoo, provides a platform for building and running large-scale enterprise AI applications. Leveraging big data, machine learning, LLMs and vector search, it delivers fast, precise business decisions. Founded by industry veterans Jon Bratseth, Kim Johansen and Frode Lundgren, Vespa.ai counts Spotify, Yahoo and Farfetch among its clients. Although the company was founded in 2005, it open-sourced its platform in 2017 and began servicing external customers in 2021.
7/ Proxima Fusion
HQ: Munich, Germany
Founded: 2023
Headcount growth over the last 12 months: 182% to 62 employees in December
A spinout from the Max Planck Institute for Plasma Physics, Proxima Fusion is building fusion power plants with quasi-isodynamic (QI) stellarators and high-temperature superconductors. Having raised over €27m from top venture firms, the company is positioning Europe to lead the nuclear fusion industry; in an interview on the Sifted Podcast, CEO Francesco Sciortino said that fusion presents a rare opportunity to build a $100bn company.
8/ Aleph Alpha
HQ: Heidelberg, Germany
Founded: 2019
Headcount growth over the last 12 months: 178% to 217 employees in December
Aleph Alpha, a German AI startup, develops large language models (LLMs) for businesses rather than consumers. Founded by Jonas Andrulis and Samuel Weinbach, with backgrounds at Apple and Deloitte, it is now pivoting to create a “generative AI operating system” that empowers enterprises to leverage AI more effectively.
9/ Flatpay
HQ: Herlev, Denmark
Founded: 2022
Headcount growth over the last 12 months: 174% to 225 employees in November
Flatpay is a Danish point-of-sale solution tailored for small, owner-managed businesses like restaurants, cafes and independent shops. With its flat-fee model, it simplifies payment tracking for SMEs, giving them a hassle-free way to manage transactions. As the company scales across Denmark, Finland and Germany, it’s helping local businesses keep up with the growing demand for digital payment solutions.
10/ Filigran
HQ: Asnières-sur-Seine, France
Founded: 2022
Headcount growth over the last 12 months: 170% to 89 employees in November
Filigran offers an open-source platform that integrates threat intelligence, adversary simulation and crisis response to help organisations stay ahead of cyber threats. Founded by ex-ANSSI cyber expert Samuel Hassine, Filigran serves over 3,500 organisations globally, including Airbus, Hermès, SpaceX and security agencies like the FBI.
Read the orginal article: https://sifted.eu/articles/europe-fastest-growing-startup-teams-by-headcount-in-2024/
