Top Series A companies in the United Kingdom

Companies that have closed a Series A - product-market fit confirmed and scaling. Filtered to companies headquartered in the United Kingdom.

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Built from a search like: “Top Series A companies in the United Kingdom”

Ranked by current headcount across Series A companies headquartered in the United Kingdom. Refreshed daily.

1
Asda· Leeds, England, United Kingdom
It’s hard for anyone to imagine just how many different career possibilities there are at Asda. Ours is a big business, and beyond the roles you might be familiar with on the shop floor (or on your doorstep), there are hundreds of others you don’t get to see. In fact, because our business is changing so rapidly, there are new roles being created at Asda all the time. Technology is changing how we do things every day, helping us to reimagine retail to make life better for our customers, in-store and online. For those with imagination, can-do, integrity and a willingness to embrace change, the possibilities at Asda are limitless. Take a look around and see where a career at Asda could take you.
- Series A
- 52.7k employees
- Founded 2024
2
Google DeepMind· London, England, United Kingdom
We’re a team of scientists, engineers, machine learning experts and more, working together to advance the state of the art in artificial intelligence. We use our technologies for widespread public benefit and scientific discovery, and collaborate with others on critical challenges, ensuring safety and ethics are the highest priority.Our long term aim is to solve intelligence, developing more general and capable problem-solving systems, known as artificial general intelligence (AGI). Guided by safety and ethics, this invention could help society find answers to some of the world’s most pressing and fundamental scientific challenges. We have a track record of breakthroughs in fundamental AI research, published in journals like Nature, Science, and more.Our programs have learned to diagnose eye diseases as effectively as the world’s top doctors, to save 30% of the energy used to keep data centres cool, and to predict the complex 3D shapes of proteins - which could one day transform how drugs are invented.
- Series A
- 10.3k employees
- Founded 2010
3
Zenith· London, England, United Kingdom
Zenith is the ROI Agency. Our more than 6,000 specialists across 95 markets offer unparalleled capabilities in Media, Data, Technology, Commerce and Content. We put effectiveness at the heart of our work to solve complex challenges, drive successful business outcomes, and grow our clients’ businesses. Zenith is part of Publicis Media, the media arm of Publicis Groupe [Euronext Paris Fr0000130577, CAC40].
- Series A
- 5.4k employees
- Founded 1988
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4
Mind· Stratford, England, United Kingdom
We’re Mind, the mental health charity.We believe no one should have to face a mental health problem alone. We’re here for you. Today. Now. We’re on your doorstep, on the end of a phone or online. Whether you’re stressed, depressed or in crisis. We’ll listen, give you support and advice, and fight your corner. And we’ll push for a better deal and respect for everyone experiencing a mental health problem.Please note our LinkedIn page is moderated 10am-6pm Mon-Fri and is not a crisis support service. If you need urgent support for your mental health please contact NHS 111 or the Samaritans on 116 123. Mind's Infoline provides information and support to people experiencing a mental health problem and is open 9am-6pm Mon-Friday except Bank Holidays. The number is 0300 123 3393
- Series A
- 3.3k employees
- Founded 1946
5
Jellyfish· London, England, United Kingdom
Jellyfish | Move Faster. Smarter. Together. We’re an integrated global digital marketing business, reinventing marketing for progressive brands. Powered by human genius, cutting-edge tech and Generative AI, we create campaigns that move at the speed of digital. #MoveFaster #MoveSmarter #MoveTogether
- Series A
- 2.2k employees
- Founded 2005

6
We Are Social· London, England, United Kingdom
We are a global socially-led creative agency, with unrivaled social media expertise.With over 1,300 people in 19 offices around the world, we deliver a global perspective to our clients in a time when social media is shaping culture.We make ideas worth talking about. We understand social behaviours within online communities, cultures and subcultures, spanning the social and gaming landscape.We work with the world’s biggest brands, including adidas, Samsung, Netflix and Google, to reach the right people in a strategic, relevant and effective way.We Are Social is part of Plus Company.
- Series A
- 1.9k employees
- Founded 2008
7
Kodland· London, England, United Kingdom
Kodland is an international online school of digital skills for children and teenagers from 6 to 17 years old. We teach programming, digital creativity and basic computer knowledge. The company started in 2018 and grew quickly throughout the years. Today, Kodland has 16,000 students and 1,000 teachers. The geography of the site is constantly expanding and includes over 40 countries. Our courses’ syllabuses are developed by teachers with extensive professional experience in Computer Science and are taught by qualified instructors. We are working on an international goal: to create the best educational content on the EdTech market, which will help our students to study effectively and gain the necessary knowledge to implement their own projects. Our team values: We enjoy what we do We value our colleagues and mark their positive results We feel our own contribution to the development of the company. If you feel that our values and goals are close to you, join our team to contribute to the education of children!
- Series A
- 1.6k employees
- Founded 2018
8
Influencer· London, England, United Kingdom
Influencer is a global creator marketing agency on a mission to shape the future of marketing by humanizing brands. By placing creators at the center, the agency delivers creator-first solutions across creative, media, and commerce that connect brands with audiences through insight-driven creator campaigns built to stop the scroll and drive measurable impact.Founded in 2015 by YouTuber-turned-entrepreneur Caspar Lee and entrepreneur Ben Jeffries, Influencer is the world’s largest independent creator marketing agency - powered by a unique ecosystem of proprietary technology, platform partnerships, and longstanding talent relationships.As an Official Global Marketing Partner of TikTok, YouTube, Pinterest, Snap, Meta, and Twitch, Influencer delivers bespoke, enterprise-level solutions powered by Waves, its AI-driven operating system. From concept to conversion, the agency blends human instinct with platform intelligence to drive measurable outcomes across the full funnel - from brand perception to performance and sales.With 200+ team members speaking 30 languages across North America, Europe, and the Middle East, Influencer has delivered 6,000+ campaigns for leading brands including Spotify, SharkNinja, Google, Nike, Disney, and Coca-Cola.
- Series A
- 1.4k employees
- Founded 2015
9
Prolific· Greater London, England, United Kingdom
Prolific is a technology company building the biggest pool of quality human data in the world—and the ultimate platform to access it.Over 35,000 AI developers, researchers, and organizations use Prolific to gather data from real, engaged participants—with a new study launched every 2 minutes.Prolific has been ranked among the fastest-growing businesses in the Financial Times 1000 in 2025 & 2024 and the Deloitte Technology Fast 50 in 2023.
- Series A
- 1.4k employees
- Founded 2014
10
SMS· Glasgow, Scotland, United Kingdom
SMS Energy is a trusted energy infrastructure and solutions partner, supporting organisations, energy suppliers and the public sector in reducing energy costs, consumption and carbon emissions. We provide integrated services across metering, energy data, utility infrastructure, energy management, flexibility services and low-carbon solutions. Through our expertise in smart technologies, carbon reduction, renewable energy and sustainable infrastructure, we help customers transition to a more efficient, resilient and low-carbon energy future.
- Series A
- 1.2k employees
- Founded 1995

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Find engineers at Series A companies in the United Kingdom

Series A companies in the United Kingdom are some of the fastest-moving employers in the market. The list above ranks the largest Series A-stage companies headquartered in the United Kingdom by current headcount, drawn from public LinkedIn and Crunchbase records. With 1,041 matching companies in Refolk’s index, the density of senior engineers, designers, and founders is unusually high.

At Series A, teams tend to be small, ambitious, and on the hunt for senior talent. The companies on this list are good signals for where the the United Kingdom talent market is heating up - and for which engineers and founders are about to become tomorrow’s operators.

Refolk converts this list into a live search. Ask for “founders of Series A companies in the United Kingdom” or “senior engineers at Series A companies in the United Kingdom hiring” and Refolk returns a ranked shortlist with evidence behind each match.

How this list is built

Refolk pulled Series A companies headquartered in the United Kingdom from public LinkedIn and Crunchbase records, ranked them by current employee count, and kept those with at least 5 employees. The list refreshes once a day.

Last refreshed: Wed, 05 Aug 2026 16:03:34 GMT

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How is this ranking built?

The list draws on the public company graph - headcount and growth signals, funding history, and recency. The criteria chips at the top show exactly which filters produced it, and the methodology section explains the ranking.

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