YC F25 Startup Multifactor Raises $15M Seed Round to Make Online Accounts Safe for AI Agents

Nexus Venture Partners leads round as demand surges for provably secure, shareable access to online accounts

SAN FRANCISCO, Dec. 4, 2025 /PRNewswire/ -- Multifactor, the post-quantum security platform enabling the safest access to online accounts for both humans and AI agents, today announced it has raised $15 million in seed funding. The round was led by Nexus Venture Partners, with participation from Y Combinator, Taurus Ventures, Honeystone Ventures, Flex Capital, Pioneer Fund, Ritual Capital, Liquid2 Ventures and leading operators across security, AI and enterprise software including Mohan & Padma Warrior, Gokul Rajaram and Mathilde Collin.

The fundraise follows strong early demand for Multifactor's first-of-its-kind technology that allows anyone to share online account access without exposing underlying credentials. Multifactor's unique approach replaces the need for traditional password managers, turning any online account into a shareable 'read-only' link in the same manner to how Google Docs can be shared for viewing or editing. With Multifactor, banking platforms, email, calendars, social accounts, and enterprise systems can all be turned into a secure, revocable, one-click access link for use by humans or AI that never reveals underlying passwords or credentials. Permissions can be set to read-only, restricted by feature, or even limited by dollar amount, offering maximum ease and convenience. All activity is audited and recorded with cryptographic signatures, and is protected through Multifactor's mathematically unbreakable, post-quantum security technology.

Founded by Ph.D. computer scientist and former CIA officer Vivek Nair, and Ph.D. mathematician and cryptographer Colin Roberts, Multifactor was built in response to a growing class of security risks created by the rapid rise of agentic AI. For AI agents, Multifactor provides a provably safe execution environment that prevents prompt injection, password theft, confused-deputy attacks, and the growing category of cross-agent hijacking incidents. Access is entirely capability-based: agents can only see or modify what the user has granted in advance.

"Passwords were never built for the agentic era, and they're becoming the most fragile link in modern security," said Vivek Nair, CEO and co-founder of Multifactor. "People aren't going to hand AI agents the keys to their calendars, finances, or business systems unless they have complete confidence nothing will go wrong. Multifactor is the easiest, safest, and most verifiable way to collaborate with both humans and AI with security guarantees that are mathematically unbreakable."

Launched to the public three weeks ago, Multifactor's platform is based on a decade of cutting-edge cybersecurity research, and is informed by the founders' experience deploying offensive and defensive tooling inside high-risk national security environments. With identity as the root cause of the majority of application security breaches, Multifactor is driving a fundamental shift away from fallible, fragmented and inconvenient password and credential-based systems, offering a provably secure zero-trust solution that cryptographically guarantees that only authorized users can access sensitive data.

"Multifactor is solving a multi-billion-dollar problem," said Abhishek Sharma, managing director at Nexus Venture Partners. "Adoption of any new technology starts with trust. That, ultimately, is what Multifactor is bringing to the table. They're creating trust. And by doing that, they're eliminating one of the most significant barriers to mainstream adoption of agentic AI."

About Multifactor
Multifactor is the security platform for the AI era. Using patented post-quantum cryptographic techniques, Multifactor enables anyone to share online accounts securely without ever exposing passwords or underlying credentials, making collaboration with humans and AI agents both safe and effortless. Multifactor is backed by Nexus Venture Partners, Y Combinator, and leading investors across security, AI, and enterprise software. Multifactor's mathematically-guaranteed account manager is free to use and is now available at www.multifactor.com.

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SOURCE Multifactor