OpenRouter Raises $40 Million to Expand Enterprise AI Inference Platform

OpenRouter has raised $40 million in combined Seed and Series A funding led by Andreessen Horowitz (a16z) and Menlo Ventures, with participation from Sequoia Capital and several industry angels, announced in a press release. The company plans to use the funding to accelerate product development, expand enterprise offerings, and add new model types to its platform.

OpenRouter provides a unified interface for large language model inference, giving developers and enterprises access to more than 400 models from providers such as OpenAI, Anthropic, Google, and Mistral through a single API. The platform enables unified billing, reporting, and management while supporting automatic multi-cloud failover and zero-logging by default.

According to the company, its inference spend grew from an annual run rate of $10 million in October 2024 to over $100 million by May 2025. More than one million developers have used its API since launch. Customers include startups and multinational corporations that use OpenRouter to manage AI workloads across multiple providers.

OpenRouter has also collaborated with OpenAI on early access to models such as GPT 4.1, providing data and feedback from real-world use. The company was founded in 2023 by Alex Atallah and Louis Vichy and positions itself as an infrastructure provider for organizations operating across multiple AI models.