BREAKING: Browserbase Raises $40M Series 🅱️ to Power AI Agents & Vibe Coders

Paul Klein IV, Founder & CEO | $300M Valuation, Raising $67.5M in just 15 months

Jun 17, 2025

Powering the Future of Web Automation Infrastructure

Paul Klein IV, founder and CEO of Browserbase just announced their $40 million Series B at a $300M valuation, led by Notable Capital (fka GGV). In addition, 🅱️ is launching a brand new product, Director for “vibe coders.” This brings Browserbase’s total funding to $67.5 million in just 15 months (!!) since founding the company. Existing investors include big Silicon Valley funds like Kleiner Perkins, CRV, Basecase, and more. Glenn Solomon of Notable Capital will be joining the board with this new round.

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Collecting what Paul calls “Thanos’ rings of investors,” the company has attracted a network of high profile angel investors including: Twilio CEO Jeff Lawson, Vercel founder Guillermo Rauch, Stripe co-founder Patrick Collison, and the founders of Okta, WorkOS, Stitch, and others. Underscoring its positioning as a developer infrastructure company solving foundational problems in the AI workflow stack.

Browserbase is powering the next generation of AI agents and “vibe coders” by providing programmable, cloud-hosted browser infrastructure, what Paul calls “Twilio for headless browsers.” Reaching 20,000 developer signups and 50 million browser sessions to date.

Special thank you to John Lagomarsino at Strike Capital for the introduction, as well as Bucky Moore & Turner Novak for some incredible questions. This is an awesome interview.

We cover:

How Browserbase works & real-world use cases (Kalshi, Dentists, Farmers)
Launching Director for “vibe coders”
Round dynamics, fundraising strategy & investor support
Their all-star angel network: Jeff Lawson (Twilio), Patrick Collison (Stripe), Guillermo Rauch (Vercel), founders of Okta, Stitch, WorkOS, WeWork, & more
The evolution of their brand (emoji logo story)
GTM strategy, scaling past 1,000 customers, 20,000 developer signups & 50 million browser sessions to date
The future of AI agents, authentication, and automation
Paul’s solo founder journey and team culture in SF
Browserbase Careers

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TIMESTAMPS:

00:00 - Series B Fundraise Announcement

02:21 - Introduction to Browserbase

04:04 - Use Cases & Applications

07:56 - Customer Growth & Product Development

10:48 - GTM & Branding Strategies

22:53 - AI Agent Ecosystem & Authentication

28:08 - AI Regulation & Deep Fakes

30:07 - Launching Director AI

30:54 - Empowering Vibe Coders

33:52 - Customer Service & Team Composition

41:28 - Why Founding a Startup Should Be Last Resort

44:38 - Brex Segment: Managing Performance As A Solo Founder

48:38 - Future Outlook & Kalshi Predictions

DEEP DIVE: Browserbase

Building Browser Infrastructure for the AI Era

Browserbase provides a cloud-based browser infrastructure layer that enables developers and AI systems to programmatically interact with the web. Its core offering, headless & scalable browsers, serve as a runtime for automated workflows across web interfaces. Developers can integrate these capabilities using Browserbase’s framework, Stagehand, which offers a code interface for fine-grained browser control.

Common use cases span both routine and bespoke workflows that lack APIs or structured integrations, such as filing franchise taxes, checking professional credentials, or navigating legacy websites in regulated industries. Customers range from startups to large enterprises automating back-office tasks, data collection, and operational workflows that rely on browser-based interactions.

The infrastructure is designed to serve as a primitive within broader agent ecosystems and LM-powered applications, providing the browser as one of many external tools accessible to an AI system.

“If you want AI to do the same work that you do on the web, you need to give it a browser,” Klein explains. “We provide that browser, at scale, as infrastructure.”

Important Term: MCP (Model Context Protocol), a standardized way for developers to expose tools, like browser control, as callable functions within an AI agent’s context. It allows agents to access capabilities such as web automation by integrating them directly into the model’s toolset. For Browserbase, MCP enables developers to connect their browser infrastructure to agents, so the AI can navigate and interact with websites programmatically, just like a human would.
“It’s just one way of letting your model call tools like ours from within its context, so your agent can actually take action on the web.”

Real-World Use Cases: From Kalshi to Dentists

Browserbase powers automation across the messy parts of the internet, enabling agents and applications to interact with websites the way a human would, through a browser. Use cases include everything from filing state taxes to automating credential checks and scraping structured data from legacy websites.

As Klein notes, “There are tens of thousands of websites that aren’t going to ship a first-party AI integration anytime soon. That’s where we come in.”

A fun example is Kalshi, the first federally regulated prediction market platform, which Browserbase can automate how AI agents interact with its frontend, navigating to specific markets, selecting hot wagers, and placing trades. “You can tell your agent to go to Kalshi, find the market on interest rates, and place $50,” Klein explains. “That interaction requires reading, clicking, and filling forms on a webpage, exactly what Browserbase is built for.”

Other high-volume use cases include:

Scraping web data from legacy websites to feed LLMs or dashboards, such as collecting commodity quotes or pricing data from overseas markets (e.g., lumber prices in Mexico)
Searching local directories (e.g., identifying 7-Elevens open in Japan)
Credential verification, like checking professional licenses from government databases
Form automation, including tasks like renewing registrations, downloading recurring reports, or submitting compliance documentation

One of Browserbase’s more surprising success stories comes from a solo developer at a 55-year-old dairy hauling company. Using Browserbase, they built an assistant that scraped gas prices along delivery routes to optimize refueling decisions. Previously, this had been a manual task handled by operations staff.

And then there’s the dentist. “We kept hearing from professionals trying to automate one niche but repetitive task,” Klein recalls. “This dentist booked a call saying they wanted to use AI to automate an insurance portal. That’s when it clicked, we needed to make the product more accessible.”

That insight led to the launch of Director, Browserbase’s new natural language tool for “vibe coders,” technical operators who may not write full applications but want to build browser-powered workflows using simple prompts. More on this below!

New Product Launch: Director

Coinciding with the Series B, Browserbase launched a new product called Director, a natural language-based agent builder aimed at non-technical “vibe coders.” This tool allows users to describe a task in plain language and receive an executable browser workflow in return. Director aims to accelerate proof-of-concept development and empower technical and non-technical teams alike.

“Hey, like we are trying to automate this back office thing. I have cursor, I have cloud code and I want to try and do this thing. I wanna use browserbase. “

With Director, users can simply describe a task in natural language like:

“Go to the California nursing license database, search for Julia with license number #####, and tell me if her credential is active.”

Director then generates a workflow that uses Browserbase’s headless infrastructure under the hood to execute the task. Users can run the script immediately, hand it off to an engineer, or integrate it into a broader application.

This approach lowers the barrier to automation. Instead of needing an entire product team to validate a workflow, operators can now build proof-of-concepts themselves, test results in real time, and scale with support from engineers later. Klein likens it to “V0 for browser automation,” or “a lovable MVP for people trying to get something working fast.”

Director is also a strategic move to accelerate adoption. As companies look for ways to automate repetitive workflows in finance, healthcare, logistics, and compliance, Director gives them a way to explore the power of browser automation without the typical friction of dev cycles or API availability.

“It’s our way of meeting the market where it is,” says Klein. “People don’t want to ask their engineering team to build another script just to check if someone’s licensed. With Director, they can do it themselves.”

🅱️rand Identity: Emoji Origin

🅱️rowserbase’s distinct brand identity was initially defined by an unconventional choice: an emoji. Inspired by the idea that having an emoji associated with the brand would put their “logo on every keyboard,” the team embraced the emoji early on. This helped solidify visual recognition and align with the company’s vision of modular developer primitives: the 🅱️uilding 🅱️locks that could stack.

Over time, the brand evolved from a single emoji into a broader design language of cubes and stackable 🅱️locks. Each product, including Stagehand and the newly launched Director, is visually represented by its own colored 🅱️lock, reinforcing the idea of composable infrastructure. While the emoji itself was eventually retired due to legal limitations, the cube motif remains central to 🅱️rowserbase’s identity, visible throughout their product design and website.

Go-to-Market and Category Creation

Browserbase’s go-to-market approach blends product-led growth with top-of-funnel brand development, emphasizing market education and awareness. With over 1,000 customers already on the platform, the company’s growth has been fueled by self-service onboarding, developer evangelism, and highly visible launches tied to funding milestones.

“We’re not a traditional infra company in how we acquire customers,” Klein says. “We do more top-of-funnel awareness, brand, messaging, launches, because we’re not selling into a well-defined category. We’re creating one.”

The company has become known for high-impact launch days that act as cultural moments. “Every fundraise is a brand moment. We try to dominate the timeline for a day,” Klein says. “It’s not just about the announcement, it’s about showing people what’s possible with this new kind of infrastructure.”

Rather than traditional enterprise sales alone, Browserbase focuses on developer inspiration and brand differentiation. It has invested in video content, media moments, community events, and even tried airborne marketing (literally flying a banner over San Francisco). Strategic creator partnerships such as those with Theo Brown on YouTube complement these efforts.

The company also maintains a strong presence on X and is expanding into LinkedIn, YouTube, and other distribution channels as it targets a broader developer and enterprise audience.

Infrastructure, Not an Agent

While sometimes conflated for its work with AI agents, Browserbase positions itself as infrastructure. It does not build models or agents, but instead provides the browser interface that agents may use to complete tasks. The company views itself similarly to Twilio or Stripe, providing core primitives that others build on.

“We’re not an AI company. We don’t train models. We’re infrastructure, primitive building blocks that agents use to interact with the real world.” He likens Browserbase’s role to that of a file system or vector database, part of the toolbelt an LLM needs to perform useful tasks.

Authentication remains one of the key friction points in agent workflows. Founder Paul Klein IV notes that seamless delegated authentication, allowing agents to act on behalf of users, is a critical enabler for AI. Investors with experience in identity infrastructure are particularly aligned with this vision.

Hiring for High Agency and Ownership

A defining trait of Browserbase’s team culture is the emphasis on hiring people with a strong sense of ownership and personal agency. “You can hire layers of middle management to coordinate everything, or you can hire people who just figure it out and drive outcomes end to end,” Klein says.

This principle shows up across product, growth, and engineering. The team works without traditional PMs, engineers are expected to talk directly to customers, define what needs to be built, and see it through to adoption. “Shipping code isn’t enough,” he adds. “You need to make sure it’s used. If adoption’s low, you’re responsible for fixing that, whether it’s changing the product or writing a launch post.”

Klein views this culture as essential to scale. “The only way to grow quickly without creating bureaucratic bloat is to give people real ownership. We look for missionaries, not mercenaries, people who care deeply about the mission and are wired to take initiative.”

Browserbase Careers

It’s also a filter in recruiting. “We don’t have a clever interview test for agency, it’s vibes,” he says. “You know it when you talk to someone who’s moved across the country to work on something hard, or who’s built things before and can clearly explain the why.”

This hiring philosophy has created a feedback loop: high-agency people attract others like them, reinforcing a culture where everyone’s expected to lead. “We’re not building a company where people stay in their lanes. The line between building and growing is blurry by design.”

Team, Culture, & Organizational Design

With a 30-person team based in San Francisco, Browserbase is doubling its headcount following the fundraise. The company maintains a strong in-office culture, emphasizing high trust, personal ownership, and transparency. Its engineering to go-to-market split is roughly 2/3 to 1/3.

The team operates without product managers, encouraging engineers to define requirements and stay close to customers. Browserbase also prioritizes customer support, investing in a technically capable customer engineering team that supports developers directly in implementation and optimization.

“We’re an emotionally vulnerable company,” Klein shares. “We do exercises like going around and saying what we’ve messed up lately. That openness builds trust and risk-taking.”

Cultural values include emotional openness, assumption of best intent, and an “ownership mindset” that encourages engineers to think beyond code and contribute across growth, community, and customer outcomes.

Klein also emphasizes the importance of hiring former founders. “They get it. They understand the pressure and the stakes. And they come in already aligned to what we’re building.”

Paul’s Background

Paul Klein IV, a solo founder, previously led teams at Twilio, where he interned during its IPO. He later co-founded Stream Club, which was acquired by Mux.

As a solo founder, Klein’s path to building Browserbase wasn’t driven by startup romanticism, it was pragmatic. “Starting a company should be a last resort,” he says. “No one else was building the infrastructure I needed. I knew I was the right person to build it, so I did.”

His experience at Twilio and his prior startup (Stream Club, acquired by Mux) shaped his approach. “With Stream Club, I didn’t have a deep emotional connection to the problem. This time, I’m obsessed. I’ve sacrificed a lot to get here, but the momentum keeps me going.”

Outlook

Looking ahead, the company plans to continue expanding its infrastructure capabilities while enabling more people both engineers and “vibe coders” to automate web tasks. While not directly building AI models, Browserbase is positioned as a foundational layer for the emerging agent ecosystem.

In Klein’s words: “We want to build the default browser for AI.”