The company announces funding from FirstMark, Bessemer Venture Partners, and Bedrock as it hits #1 trending on GitHub
NEW YORK, Aug. 19, 2025 /PRNewswire/ — TensorZero, a technology startup building an open-source stack for industrial-grade LLM applications, announced today its seed funding round of $7.3M. The round is led by FirstMark, with participation from Bessemer Venture Partners, Bedrock, DRW, Coalition, and dozens of strategic angel investors.
TensorZero’s open-source stack unifies an LLM gateway, observability, optimization, evaluation, and experimentation. “Despite all the noise in the industry, companies building LLM applications still lack the right tools to meet complex cognitive and infrastructure needs, and resort to stitching together whatever early solutions are available on the market,” says lead investor Matt Turck, General Partner at FirstMark. “TensorZero provides production-grade, enterprise-ready components for building LLM applications that natively work together in a self-reinforcing loop, out of the box. The enthusiasm we hear from users makes the difference clear.”
Recently, TensorZero’s open-source repository achieved the ‘#1 trending repository of the week’ spot globally on GitHub. “The surge in adoption from both the open-source community and enterprises has been incredible. We’re fortunate to have received contributions from dozens of developers worldwide, and it’s exciting to see TensorZero already powering cutting-edge LLM products at frontier AI startups and large organizations, including one of Europe’s largest banks,” says co-founder and CEO Gabriel Bianconi.
TensorZero’s open-source stack sets the foundation for the company’s mission of helping LLMs automatically learn from real-world experience. “As AI models grow smarter and take on more complex workflows, you can’t reason about them in a vacuum; you have to do so in the context of their real-world consequences. It’s like a talented person starting a brand-new job: they may stumble on day one, but with instruction and experience, they rapidly improve,” says co-founder and CTO Viraj Mehta. “Our ultimate vision is to enable a data and learning flywheel for optimizing LLM applications — a feedback loop that turns production metrics and human feedback into smarter, faster, and cheaper models and agents.”
The team behind TensorZero brings deep expertise in AI and software infrastructure. Viraj Mehta (CTO) previously received a PhD from Carnegie Mellon focused on reinforcement learning for nuclear fusion and LLMs; he holds a BS in math and an MS in computer science from Stanford. Gabriel Bianconi (CEO) was the chief product officer at Ondo, one of the largest decentralized finance projects with over $1B in AUM; he holds BS and MS degrees in computer science from Stanford. The team also includes former maintainers of major open-source projects such as the Rust compiler, machine learning researchers (Stanford, CMU, Oxford, Columbia) with thousands of citations, and other talented technical contributors.
The capital will accelerate TensorZero’s efforts to build best-in-class open-source infrastructure for LLM engineers.
About TensorZero
TensorZero is an open-source stack for industrial-grade LLM applications. It unifies an LLM gateway, observability, optimization, evaluation, and experimentation. The company is funded by FirstMark, Bessemer, Bedrock, and dozens of other strategic investors. For more information, visit https://www.tensorzero.com.
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