Lightsage, an early-stage startup officially known as API-Rex Inc., has raised $4 million in seed funding to help software companies sell their products directly to autonomous AI agents. The round was led by Nexus Venture Partners, with participation from prominent angel investors including Postman Inc. Chief Executive Abhinav Asthana, DocuSign Inc. President Robert Chatwani, Apollo GraphQL CEO Matt Curl, and former Salesforce Inc. Chief Technology Officer Steven Tamm. The company aims to address a shift in how software is discovered and purchased, as human developers increasingly delegate those tasks to AI coding agents.
The startup argues that software vendors can no longer focus their marketing efforts solely on human users. With the rise of autonomous agents such as Claude Code, Microsoft Corp.’s Copilot, and Cursor, humans are less involved in the software engineering process, and developers now let their AI agents choose the most appropriate software on their behalf rather than reading documentation or browsing websites. Lightsage co-founder and CEO Jun Liang Lee said the industry is moving from an internet where AI tells people which software to use to one where AI uses the software itself, meaning visibility still matters, but the real test is whether an agent can understand a product and achieve a successful outcome.
To address this, Lightsage has developed a concept called agent-led growth, where software developers increase adoption of their tools by specifically targeting AI agents. Its platform runs simulations across multiple coding agents and answer engines to help companies view their offerings from the perspective of the agents. The platform provides AI agents with real-world integration tasks, instructs them to shop for software, and then measures how visible a customer’s product is compared with rival platforms before getting the agent to actually use the product.
When an agent fails to complete a task using a customer’s software, Lightsage identifies the cause, such as confusing documentation, broken API endpoints, flawed authentication, or incompatible Model Context Protocol servers, and then shows the customer how to fix the issue. The company also offers analytics on agentic traffic visiting customer websites, providing insights into which agents are using their software, for which tasks, and how often. Lee said every software company will eventually need to optimize for that journey to unlock agent-led growth.
Lightsage is currently focusing on developer software, an area where AI agents have already become widespread. Its platform has been used by firms including Reducto, Daytone, Firecrawl, Rime, and Tinyfish to understand why agents sometimes choose their platforms over competitors. The startup now plans to expand its commercial and engineering teams and grow its capabilities in analytics, attribution, evaluation, and optimization across APIs, software development kits, command line interfaces, and agent skills.
Abhishek Sharma of Nexus Venture Partners said the direction of the digital economy is clear, noting that while the internet brought the economy online with humans discovering and transacting through digital channels, AI is shifting that agency from humans to agents that can discover, evaluate, and act on a user’s behalf. He said Lightsage is building intelligence infrastructure for that new era of autonomous browsing, helping companies optimize for agent conversion. The company eventually hopes to spread the agent-led growth concept to other fields, such as business-to-business software, cloud infrastructure, and automated payments.
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