A San Francisco financial software company that automates the accounting grunt work for finance teams has become the latest AI startup to cross the billion-dollar threshold. Rillet closed a $100 million Series C financing round that values the company at $1 billion, officially making it a unicorn just two years after emerging from stealth mode in 2024.
The round, led by ICONIQ, came together in less than 48 hours, according to co-founder and CEO Nicolas Kopp, who disclosed the timeline in the a16z Build Newsletter. As citybiz reported, the Series C also drew participation from Andreessen Horowitz, Sequoia, Sequoia Global Equities, Bain Capital Ventures, Battery Ventures, Scale Venture Partners, FirstMark, Creandum, and Oak HC/FT. ICONIQ General Partner Seth Pierrepont and Andreessen Horowitz General Partner Alex Rampell both sit on Rillet's board, having backed the company through earlier rounds as well, per TNW.
This is Rillet's third major funding round in roughly 14 months. The company raised a $25 million Series A led by Sequoia in May 2025, then a $70 million Series B that August at a reported $500 million valuation, according to Crunchbase News. Rillet has now raised more than $200 million in total capital, per the citybiz report.
Growth That Doubled In A Quarter
The fundraising velocity tracks a steep growth curve. Rillet expanded its customer base to more than 600 companies ahead of the Series C, up from roughly 200 a year earlier, and it doubled its new annual recurring revenue over the three months leading into August, according to the same FinTech Futures reporting. The platform, which citybiz describes as a central workspace for finance teams, combines a general ledger, financial integrations and automated accounting workflows, using a real-time ledger and tracking every action through an audit trail while leaving employees with approval authority and final oversight.
Rillet gained its initial traction among technology and AI businesses before expanding into professional services, healthcare, biotech, fintech and logistics, per citybiz. Two customers illustrate the pitch: AI platform Mercor manages more than $2 billion in annual revenue with a finance team of just three people, and e-commerce software firm Postscript cut its monthly accounting close down to three days, according to details reported by TNW.
Founders With Fintech Pedigree
Kopp co-founded Rillet in 2021 with Chief Technology Officer Stelios Modes, who previously served as the technical architect behind German digital bank N26's U.S. payment infrastructure, according to TNW. Kopp joined N26 in 2015 as one of its early employees and later became the company's U.S. CEO, per citybiz. Before that, he spent five years in investment banking at Morgan Stanley. Kopp holds a bachelor's degree from the University of St. Gallen in Switzerland and a master's degree in accounting from the London School of Economics, according to the citybiz report.
Rillet has also built out partnerships with major accounting firms and is now an official partner of more than half of Accounting Today's top 20 firms, per citybiz. The company launched an alliance with Ernst & Young this year, and it is now targeting larger enterprise customers as it expands beyond its original base of venture-backed tech startups.
Taking On Oracle, SAP And NetSuite
Kopp has been explicit about who Rillet is trying to displace. According to co-founder Nicolas Kopp, the company's AI-native ERP is built to take on legacy enterprise finance software, including Oracle Fusion, SAP, Workday, NetSuite, and Microsoft Great Plains, as reported by CFOtech. Kopp has said the ERP must become the operating layer for what happens next in the AI era, per citybiz.
That ambition lands against a backdrop of a shrinking accounting workforce. U.S. Bureau of Labor Statistics data cited by Forbes show that the accounting and auditing workforce shrank by more than 17% between 2020 and 2026, with over 300,000 professionals leaving the field, while bookkeeping clerk positions are projected to decline by another 6% through 2034. Industry estimates value the global accounting software market at roughly $19.4 billion in 2024, with projections putting it as high as $50 billion within a decade as cloud and AI adoption accelerate, according to Grand View Research and Precedence Research.
Whether legacy giants can bolt generative AI onto their own platforms fast enough to hold market share remains an open question, as does whether slower-moving industries like biotech and healthcare will adopt AI-managed general ledgers at the same pace as high-growth tech firms. How human audit standards evolve as finance teams shrink while overseeing automated closes is also still unresolved, according to the FinTech Futures analysis.
