| # | Company | Employees |
|---|---|---|
| 1 | 92,092 | |
| 2 |
Barclayshome.barclays
A British universal bank with global presence, offering consumer banking, payments, corporate and investment banking services, supported by technology and operational solutions |
82,417 |
| 3 |
BAE Systemsbaesystems.com
The company provides advanced technology-led defense, aerospace, and security solutions, with a skilled workforce in over 40 countries, focusing on innovation and long-term commitment |
55,143 |
| 4 |
Kantarkantar.com
Global leader in marketing data and analytics with deep expertise, innovative technology, and insights to help clients understand people and drive growth worldwide |
24,976 |
| 5 |
Clarivateclarivate.com
A global information services provider connecting people and organizations to trusted intelligence in Academia & Government, Life Sciences & Healthcare, and Intellectual Property |
11,385 |
| 6 |
Publicis Mediapublicisgroupe.com
A global media company within Publicis Groupe, employing data-driven solutions and platform-based technologies to deliver client value and drive growth internationally |
11,033 |
| 7 |
Google DeepMinddeepmind.google
Advances artificial intelligence with breakthrough research. Solves complex problems like disease diagnosis, energy saving, and protein folding with safe, ethical AI. |
9,665 |
| 8 |
Acuity Analyticsacuityanalytics.com
Provides bespoke research, analytics, and technology solutions to financial services, helping institutions operate efficiently and unlock human capital to drive revenue. |
7,619 |
| 9 |
Qualitestquality-ai.com
Global leader in AI-powered Quality Engineering services, specializing in superior customer experience, accelerated release velocity, and tailored solutions for various industries |
6,088 |
| 10 |
LSEG Data & Analyticslseg.com
A global provider of financial markets data and infrastructure, enabling customers to gain insights through data, feeds, analytics, and workflow solutions |
5,147 |
| 11 |
Fitness AIguden.org
Fitness AI is a mobile app using artificial intelligence to personalize workout plans, track progress, and motivate users towards achieving health and fitness goals |
5,137 |
| 12 | 5,067 | |
| 13 |
Accenture UK & Irelandaccenture.com
A global professional services company leveraging technology, innovation, and industry expertise to drive digital transformation and deliver tangible outcomes for clients worldwide |
4,101 |
| 14 | 3,987 | |
| 15 |
WPP Productionwppproduction.com
Global content production company integrating creative producers, AI, and virtual production to deliver innovative, fast, and scalable marketing content solutions. |
3,507 |
| 16 |
Infobipinfobip.com
Global leader in omnichannel engagement, providing messaging tools and solutions for customer engagement, authentication, and security with a strong focus on quality engineering |
3,501 |
| 17 |
TryHackMetryhackme.com
It simplifies learning and teaching Cybersecurity through prebuilt courses and cloud-hosted virtual machines, ideal for CTFs, workshops, and training. |
3,445 |
| 18 |
Hogarthwppproduction.com
Creative production company combining craft, insight, and technology to bring creative work to life across global locations. |
3,262 |
| 19 |
Starlingstarlingbank.com
This company is a digital bank offering fast technology, fair service, and honest values, focused on solving customer problems and building sustainable solutions |
3,231 |
| 20 |
Tolunatolunacorporate.com
Global leader providing advanced technology and comprehensive solutions for data-driven market research, leveraging AI and extensive global panels. |
3,218 |
| 21 |
Genius Sportsgeniussports.com
This company delivers technology and expertise to sports, betting, and media partners worldwide, enhancing data collection, fan engagement, and overall performance |
3,054 |
| 22 |
NGA Human Resources, an Alight companyalight.com
Global provider of HR solutions, pioneering digital HR, payroll, compliance, and workforce data to enhance employee experiences, save costs, and transform organizations worldwide |
2,789 |
| 23 |
GlobalData Plcglobaldata.com
A leading information services company helps organizations and decision-makers predict the future, make informed decisions, and gain a competitive edge |
2,711 |
| 24 |
Dialecticadialectica.io
A B2B information services firm connecting professionals with industry experts worldwide through a trusted knowledge-sharing platform, recognized for growth and workplace excellence |
2,400 |
| 25 |
Mimecastmimecast.com
Protects humans, data, and AI agents through a unified platform, securing the workforce and their interactions with AI from cyberattacks. |
2,396 |
| 26 |
Qube Research & Technologiesqube-rt.com
Global quant and systematic investment manager using technology and data for scientific approach to investing, driving innovation for high quality returns Multiple open positions available |
2,393 |
| 27 |
Checkout.comcheckout.com
A financial technology company providing a high-performance payments platform for enterprise and scaling businesses worldwide, processing payments, payouts, and managing card programs |
2,343 |
| 28 | 2,255 | |
| 29 |
Quantanitequantanite.com
The company provides Conversational Gen AI chatbot solutions to automate customer interactions and enhance agent performance with a focus on human touch and empathy |
2,173 |
| 30 |
Krakenkraken.tech
AI-powered operating system enhancing customer satisfaction, product innovation, revenue generation, and operational savings for energy, water, and telco utilities. |
2,125 |
| 31 |
Argus Mediaargusmedia.com
Provides price assessments, news, analytics, consulting, data tools, and conferences for global energy and commodity market transparency and decision-making. |
2,024 |
| 32 |
Canonicalcanonical.com
Publishing Ubuntu, popular enterprise Linux, open source delivery, cloud to edge, secure, cost-effective, global community, developer platform, remote-first company. |
2,001 |
| 33 |
Corsearchcorsearch.com
Revolutionizing brand protection with AI-powered solutions, trademark research, and IP protection services to help companies secure, monitor, and enforce their brands globally |
1,868 |
| 34 | 1,593 | |
| 35 |
Ocean Infinityoceaninfinity.com
Innovative company using robotic technology for marine operations, data collection, and maritime solutions with a focus on sustainability and innovation |
1,591 |
| 36 |
Connectweconnect.tech
Communication experts providing solutions in Contact Centre, Unified Communications, and Network Services, delivering digital transformation through bespoke strategies for businesses globally |
1,387 |
| 37 |
Influencerinfluencer.com
Global agency delivering creator-first solutions through proprietary technology and platform partnerships to drive measurable brand impact, humanize businesses, and connect with audiences. |
1,346 |
| 38 |
ElevenLabselevenlabs.io
It develops AI audio models for speech and sound effects, enabling content creation, localization, and accessibility for various industries. |
1,291 |
| 39 |
FE fundinfofefundinfo.com
By providing accurate data, technology solutions, research, and expert insights, we connect the fund management industry to inform better investment decisions |
1,216 |
| 40 |
Leverage Edulvrg.in
A counselling product for young individuals to choose their career path, study abroad, and prepare for exams, supported by various apps and a SaaS operating system for universities |
1,204 |
| 41 |
G-Researchgresearch.com
A leading quantitative research and technology firm tackling big questions in finance using machine learning and big data for predicting market movements |
1,153 |
| 42 |
Merit Data & Technology Indiameritdata-tech.com
A company that provides marketing data, product data, customized software, and marketing automation to help B2B brands embrace the challenges of the future |
1,128 |
| 43 |
Smartstreamsmart.stream
Provides financial institutions with accurate, timely data insights to streamline operations, reduce costs, and ensure regulatory compliance confidently. |
1,114 |
| 44 |
Government Digital Servicegds.blog.gov.uk
Designing and protecting user experience for digital government, delivering exceptional initiatives, and solving high-priority challenges to make services more accessible and inclusive |
1,110 |
| 45 |
EZRAhelloezra.com
This company provides professional coaching services at scale, using technology, a global network of coaches, and metrics for personalized growth |
1,109 |
| 46 |
Brandwatchbrandwatch.com
It provides consumer intelligence, social media management, and influencer management to help businesses understand and engage with their customers effectively. |
1,100 |
| 47 |
Onclusiveonclusive.com
Global PR and Communications partner offering data-driven insights, consultancy, workflow tools, and media monitoring to elevate performance and prove value |
1,098 |
| 48 |
Facultyfaculty.ai
The company develops and implements safe AI systems integrating human and artificial intelligence for optimized performance |
1,073 |
| 49 | 1,028 | |
| 50 |
VeriParkveripark.com
This global solutions provider enables financial institutions to enhance customer experiences, drive engagement, and increase revenue through intelligent customer experience solutions |
980 |
| 51 |
Indeed Flexindeedflex.com
Revolutionary app connecting job seekers with temporary work, offering flexibility in where, when, and how they work while supporting employers with high-quality workers |
978 |
| 52 | 969 | |
| 53 |
Allica Bankallica.bank
A leading UK fintech company dedicated to supporting small and medium businesses with modern technology, local relationships, and personalized banking services |
910 |
| 54 |
Quantexaquantexa.com
Global platform connecting siloed systems to visualize complex relationships, providing single views of data for risk mitigation and strategic organizational decision making. |
895 |
| 55 |
FCM Travelfcmtravel.com
Corporate travel management with a modern platform, excellent customer service, enhanced traveler experience, cost savings, and data visibility for better business travel. |
844 |
| 56 |
Exinityexinity.com
A global company empowering ambitious individuals to achieve financial independence through innovative trading and investing products and risk management tools |
827 |
| 57 |
Synthesiasynthesia.io
AI-powered video creation platform enabling companies to produce videos in 140 languages, saving significant time and budget costs. |
800 |
| 58 |
Kiki-insurance.com
Ki leverages technology and data to streamline risk placement at Lloyd’s of London, providing instant underwriting decisions and expert assistance |
786 |
| 59 |
GAINthisisgain.com
Creative-led and insight-driven company blending data, technology, and creativity to deliver meaningful impact and bold strategies that move people, brands, and businesses forward. |
759 |
| 60 | 758 | |
| 61 |
Incubetaincubeta.com
A global team of 800+ experts across 20 offices offering digital services to unlock business growth for clients like Google, Hyundai, and Netflix |
750 |
| 62 |
Marshall Wacemwam.com
A global asset manager established in 1997, providing a variety of alternative, long-only, and custom investment options to a wide range of investors |
742 |
| 63 |
LexisNexis UKlexisnexis.co.uk
Provider of legal, regulatory, and business information and analytics helping customers improve productivity, decision-making, and support rule of law worldwide. |
719 |
| 64 | 718 | |
| 65 |
Kaluzakaluza.com
Energy software company enabling energy suppliers to streamline operations, enhance customer service, and drive decarbonisation through smart technology solutions |
710 |
| 66 |
Eagle Eyeeagleeye.com
Enabling businesses to create personalized one-to-one relationships with customers through a digital marketing platform, connecting online and offline interactions in real-time |
709 |
| 67 | 706 | |
| 68 |
MVFmvfglobal.com
This company helps businesses grow by delivering high volumes of new customers through technology and cross-channel marketing teams on a pay-per-lead basis |
695 |
| 69 |
Cleoweb.meetcleo.com
AI-powered platform providing personalized financial insights and tools through a chat assistant to improve users' money management and saving habits. |
686 |
| 70 |
OakNorthoaknorth.co.uk
digital bank offering bespoke credit and banking services to UK and US businesses with £1m-£100m turnover, supporting growth |
680 |
| 71 |
Digital Sciencedigital-science.com
AI-focused technology company providing innovative solutions to researchers, universities, funders, industry, and publishers advancing global research. |
678 |
| 72 |
Landscapelandscape.vc
Providing products and communities for entrepreneurs creating the future, and investors supporting them |
669 |
| 73 |
Toppan Digital Languagetoppandigital.com
Toppan Digital Language provides innovative language solutions for high-risk content, serving top companies globally with specialized teams and cutting-edge technology |
661 |
| 74 | 659 | |
| 75 |
Kantar Consultingkantar.com
Leading marketing data and analytics company providing global and local insights into how people think, feel, and act to help inspire growth |
655 |
| 76 |
CodeGen Internationalcodegen.co.uk
A global travel technology provider delivering innovative, scalable reservation systems to leading organizations worldwide, automating business processes with cutting-edge technology |
645 |
| 77 | 625 | |
| 78 |
Roboyoroboyo.global
Leading provider of AI-powered automation solutions. Helps organizations embed intelligence into their business, aligning people, processes, and technology for measurable outcomes and growth. |
614 |
| 79 |
Agilisysagilisys.co.uk
A trusted leader in delivering data-driven solutions and Generative AI products tailored to healthcare, government, and public sector organizations |
612 |
| 80 |
LanguageLine Solutions UKlanguageline.com
LanguageLine Solutions offers interpreting, translation, and transcription services across the UK, specializing in over 200 languages and British Sign Language |
606 |
| 81 | 599 | |
| 82 |
Infiniti Research Ltd.infinitiresearch.com
Leading provider of market and customer intelligence solutions, offering research and advisory services through unique methods to deliver actionable insights and robust market data. |
582 |
| 83 |
Moody's Analytics Knowledge Servicesacuityanalytics.com
Provider of research, analytics, and business intelligence for the financial services sector, helping clients increase revenues, innovate with technology, and transform operations |
571 |
| 84 |
MYCOM OSImycom-osi.com
Provide network assurance and service experience solutions for CSPs and enterprises to manage 5G and enterprise services efficiently. |
557 |
| 85 |
The Smart Cubethesmartcube.com
Providing custom research, advanced analytics, and technology to transform data into actionable insights for improved business performance. |
547 |
| 86 | 518 | |
| 87 |
Verticevertice.one
A spend optimization platform leveraging automation and machine learning to save companies up to 25% on SaaS and cloud costs |
509 |
| 88 |
ComplyAdvantagecomplyadvantage.com
Empowers businesses to eliminate financial crime using AI, offering a unified platform and extensive partner ecosystem for compliance, growth, and regulatory trust. |
506 |
| 89 |
Dotdigitaldotdigital.com
An all-in-one customer experience and data platform enabling marketers to exceed expectations with personalized cross-channel journeys and automated experiences |
465 |
| 90 |
Payhawkpayhawk.com
AI-native spend management platform. Orchestrates global money across bills, cards, expenses, travel, procurement for control, automation, savings. Provides global money account. |
465 |
| 91 |
Cognismcognism.com
Provides accurate, compliant B2B data and sales intelligence, enabling sales teams to find the right contacts, reach them with confidence, and close deals. |
456 |
| 92 | 454 | |
| 93 |
Acuvateacuvate.com
Empowers enterprises to accelerate next-gen transformation journeys using an AI-first approach, modernizing, automating, and transforming applications for agility in the digital world. |
444 |
| 94 |
LoopMeloopme.com
A technology company leveraging artificial intelligence to enhance brand advertising performance and outcomes |
440 |
| 95 |
Law Business Researchcentellic.com
Transforms client decision-making on strategy, growth, and risk through indispensable data, intelligence, and analysis, leveraging combined strengths in data, insight, and market access. |
439 |
| 96 | 434 | |
| 97 |
Benthanksben.com
A global flexible benefits platform reshaping the world of work by connecting the benefits ecosystem for better outcomes and work-life integration |
424 |
| 98 | 421 | |
| 99 |
InstaDeepinstadeep.com
It specializes in decision-making AI, applying machine learning across various sectors, and focuses on knowledge sharing and nurturing talent. |
405 |
| 100 |
Cerillion Technologiescerillion.com
A leading provider of billing, charging, and customer management systems for communication providers worldwide, delivering cost-effective solutions to business challenges |
392 |
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How this list is built
Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Oct 24, 2026.
More company lists in London
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- IT Services and IT Consulting companies in London 590
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