Jan Hammer

Partner at Index Ventures

📍 London, England Metropolitan Area, United Kingdom🔄 Updated September 2026💼 45 investments📅 15 years investing🗓 Last invested Mar 2026𝕏 @upgrade_to_unlock
VC🌍 United Kingdom20+ investmentsInvested this year
45
Total investments
17
Early stage
11
Mid stage
4
Late stage
15y
Years active

Portfolio

40 investments · sorted by recency
All investments
Early stage
Mid stage
Late stage
Board Observer
Mar 2026
Nous développons des solutions d’automatisation des tâches administratives hospitalières, pour réduire vos coûts opérationnels et offrir à votre personnel plus de temps pour les soins.
Board Observer
Dec 2025
Duvo automates the hard, long-running processes that break across messy enterprise stacks — ERPs, portals, phone calls, spreadsheets, and systems with no API. The stuff nobody else wants to touch. Not drafts. Not suggestions. Closed cases: systems updated, write-backs verified, evidence attached. End to end, with enterprise reliability. Cloud browsing for systems nobody else can reach. Voice for last-mile closure. Governed execution with human-in-the-loop approvals and full audit trails. No token bills. No usage surprises. One predictable subscription — so you can build a business case on day one. No technical skills needed. Enterprise-grade security. Runs 24/7. Backed by Index Ventures, Northzone, and Credo Ventures.
Board Member
Jul 2025
The largest RIAs, broker dealers, and private banks trust Moment to power investment management for their traders and advisors. Founded by former fixed income quants from Citadel and Jane Street and backed by over $50M in funding from the world’s leading investors, Moment has developed the first operating system built specifically for wealth management. With Moment’s solution, advisors can build personalized portfolios in seconds, traders can set rules to automatically execute orders at all of the major trading venues, and portfolio managers can automate reinvestment, rebalancing, and compliance monitoring. Moment is headquartered in the Financial District of New York City. Learn more below and follow the team’s rapid growth here on LinkedIn.
Board Observer
Jul 2025
We build and distribute best-in-class cash management solutions for SMEs, start-ups and fintechs. Our first products provide seamless access to risk-free rates in EUR, GBP, and USD for everyday cash management, accessible via our web app or through our API. Nous concevons et distribuons les meilleurs produits de gestion de trésorerie pour les PME, start-ups et fintechs. Nos produits sont accessibles via notre application web ou par API et peuvent être proposées en marque blanche.
Investor
May 2025
Duna is a business onboarding platform for regulated companies — including large banks, fintechs, platforms and financial institutions. Our mission is to build global trust infrastructure by providing a digital passport for every business. Over time, this will evolve into a network for shareable identity and one-click onboarding. Today, large enterprises like Plaid, CCV, Fiserv, Moss, and Bol use Duna to reduce operational costs, scale globally, and optimize conversion rates. Customers report 10.6x faster onboarding, 37% conversion increase, and 4.8x productivity gains. The Duna team comprises leaders from leading financial services and fintech companies—Stripe, Adyen, Trade Republic, Klarna—as well as technology companies such as Apple, Google, Uber, Airbnb, and Spotify. Duna has raised $45+ million from Index Ventures and CapitalG, as well as founders and executives from Stripe, Adyen, Anthropic, Goldman Sachs, and more.
Investor
Apr 2025
Cowboy Space Corporation is building a power grid in outer space for artificial intelligence. Using an integrated system of satellites and rockets, we will send high-performance compute and optical data transmission to Low Earth Orbit. Our constellation of satellites, Stampede, will harness abundant solar power to run on-orbit GPU data centers. With each launch, Stampede grows the power and compute capacity for humanity. Earths energy grid cant run at the pace of AI. We can. AI is driving the largest infrastructure buildout in recent history, and the power grid on planet Earth cant keep pace. In major US markets, average grid connection lead times for new data centers can run 5-7 years or more. Meanwhile, AI demand is flat-out outgrowing Earths pastures. Full-Stack Architecture: Traditional architecture treats the rocket as a workhorse and the satellite as freight. In our system, the rockets upper stage is the satellite itself. Its a 1-megawatt data center with active thermal management and integrated compute, designed as one unified vehicle from the ground up. We trim the fat on redundant structure and avionics, dedicating every possible kilogram of compute to Low Earth Orbit. By owning our manufacturing and dedicated launch sites, we vertically integrate core technologies that enable deploying compute at scale. We’ve raised a $275M Series B at a $2B valuation led by Index Ventures, with participation from new investors IVP, Blossom Capital, and SAIC, alongside existing investors Breakthrough Energy Ventures, Construct Capital, Andreessen Horowitz, NEA, Interlagos and Baiju Bhatt.
Board Observer
2024
We are forging the worlds most advanced mathematical reasoning engine
Board Observer
2024
Valdera is a sourcing platform for chemicals and raw materials. Our technology empowers companies to find the specialized inputs and formulations they need to build the future of sustainable & branded products.
Investor
2024
Tebi is an all-in-one hospitality platform consolidating essential business tools into a single elegant solution. The hospitality industry suffers from oversubscription, with independent business owners juggling 10+ separate subscriptions just to operate effectively. Were simplifying operations so owners can focus on what they do best: serving customers. Tebi OS brings together everything hospitality businesses need: Point of Sale, Reservations, Payments, Kitchen Display Systems, QR Ordering, Takeaway, Inventory, and Multi-location reporting - all seamlessly integrated. Unlike traditional setups where systems fail to communicate, Tebi ensures all components work flawlessly together. Weve transformed a fragmented technology stack into one cohesive system that works for restaurants, cafes, bars, bakeries, nightclubs, and venues of all sizes.
Board Member
Sep 2023
Every small business is a big deal. SMBs have a major impact on the lives of their owners, as well as the macroeconomic success of their communities and national economy. Despite their significant impact, these businesses often lack access to tools and resources, leaving them vulnerable. As a result, very few end up making it. Apron is focused on helping more small businesses make it. The biggest threat to small business is cash flow, often stemming from a gap between the demand payments put on owners and the aptitude to make the payments effectively. At Apron we are closing the gap by digitising and simplifying the payments process. Whether capturing invoices, enabling collaboration for approvals, or combining long lists of invoices into one simple batch pay solution, Apron is your Powertool for Payments. Over time Apron will enable business owners to coordinate all outgoing and incoming payments, streamlining time and effort so you are freed up to focus on the business as a whole. By flipping payments from painful to powerful, Apron is amplifying the next generation of economic drivers. Apron Your Business Paid For
Investor
Jun 2023
Frontier AI. In your hands. We believe in a future where AI is abundant and accessible. We aspire to empower the world to build with—and benefit from—the most significant technology of our time. Join us: https://jobs.lever.co/mistral/
Investor
May 2023
Tema builds institutional-quality ETF solutions for all market environments, spanning high-conviction growth opportunities, durable core exposures, and alternatives. Founded in 2022, Tema is led by veterans of the ETF and global asset management industry, and backed by Index Ventures, Accel, Zinal Growth, and over a dozen financial services CEOs and fintech founders.
Investor
Nov 2022
Atlar helps modern finance teams manage money. Companies like Aiven, Acne Studios, GetYourGuide, Liberis, Natural Cycles, and Zilch use Atlar to get a single place for cash management, payments, forecasting, reports, and more. Integrated with all your banks and ERP and live within weeks. Our modern treasury platform lets you centralize your cash positions, payments, and much more besides in a single interface thats fast and easy to use. This gives you the tools to optimize liquidity, manage risks, and automate payments in real time—while leaving multiple bank logins, manual file uploads, and spreadsheets behind. Atlar is headquartered in Stockholm, Sweden, and backed by Index Ventures and General Catalyst. If youre interested in seeing the Atlar platform for yourself, reach out to our team.
Board Observer
Apr 2022
Bank and card payments, BLIK, refunds, financing & shipping for online stores. Join 6,000 ecommerce merchants & start enjoying low fees & top-notch customer support today.
Board Member
Feb 2021
Jsme online supermarket s nejrychlejším doručením ve městě a taky skvělá parta lidí, kteří chtějí našim zákazníkům umožnit jíst a žít lépe. Zajišťujeme prostě boží jídlo a boží službu. Máme stále srdce start-upu a milujeme rychlost. Buďte v tom s námi ;-) Rohlík.cz, to je - přes 200 tisíc zákazníků v Praze a Brně - - sklad v Praze a Brně - - 200 CNG aut, které rozváží nákupy - - Tomáš Čupr, člověk, co vybudoval Slevomat a DámeJídlo - - expanze do Maďarska - - vymýšlení nových věcí - - krásné kanceláře v Karlíně -
Show all 40 investments ↓
Experience · 47 entries
All (47)
Investments (45)
Board (34)
2026
Board Observer
Mar 2026
Nous développons des solutions d’automatisation des tâches administratives hospitalières, pour réduire vos coûts opérationnels et offrir à votre personnel plus de temps pour les soins.
2025
Board Observer
Dec 2025
Duvo automates the hard, long-running processes that break across messy enterprise stacks — ERPs, portals, phone calls, spreadsheets, and systems with no API. The stuff nobody else wants to touch. Not drafts. Not suggestions. Closed cases: systems updated, write-backs verified, evidence attached. End to end, with enterprise reliability. Cloud browsing for systems nobody else can reach. Voice for last-mile closure. Governed execution with human-in-the-loop approvals and full audit trails. No token bills. No usage surprises. One predictable subscription — so you can build a business case on day one. No technical skills needed. Enterprise-grade security. Runs 24/7. Backed by Index Ventures, Northzone, and Credo Ventures.
Board Member
Jul 2025
The largest RIAs, broker dealers, and private banks trust Moment to power investment management for their traders and advisors. Founded by former fixed income quants from Citadel and Jane Street and backed by over $50M in funding from the world’s leading investors, Moment has developed the first operating system built specifically for wealth management. With Moment’s solution, advisors can build personalized portfolios in seconds, traders can set rules to automatically execute orders at all of the major trading venues, and portfolio managers can automate reinvestment, rebalancing, and compliance monitoring. Moment is headquartered in the Financial District of New York City. Learn more below and follow the team’s rapid growth here on LinkedIn.
Board Observer
Jul 2025
We build and distribute best-in-class cash management solutions for SMEs, start-ups and fintechs. Our first products provide seamless access to risk-free rates in EUR, GBP, and USD for everyday cash management, accessible via our web app or through our API. Nous concevons et distribuons les meilleurs produits de gestion de trésorerie pour les PME, start-ups et fintechs. Nos produits sont accessibles via notre application web ou par API et peuvent être proposées en marque blanche.
Investor
May 2025
Duna is a business onboarding platform for regulated companies — including large banks, fintechs, platforms and financial institutions. Our mission is to build global trust infrastructure by providing a digital passport for every business. Over time, this will evolve into a network for shareable identity and one-click onboarding. Today, large enterprises like Plaid, CCV, Fiserv, Moss, and Bol use Duna to reduce operational costs, scale globally, and optimize conversion rates. Customers report 10.6x faster onboarding, 37% conversion increase, and 4.8x productivity gains. The Duna team comprises leaders from leading financial services and fintech companies—Stripe, Adyen, Trade Republic, Klarna—as well as technology companies such as Apple, Google, Uber, Airbnb, and Spotify. Duna has raised $45+ million from Index Ventures and CapitalG, as well as founders and executives from Stripe, Adyen, Anthropic, Goldman Sachs, and more.
Show all 47 entries ↓
Investment activity
2011–2026 · 45 investments
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