Photon raises $4.5M to replace mobile apps with AI agents

San Francisco-based startup Photon has secured $4.5 million in seed funding to advance its platform for building AI agents that operate within existing communication channels. The seed round was co-led by Gradient and A*, with participation from Vercel, HongShan, Z Fellows, Llama Ventures, and Karman. To mark its belief that messaging-based agents will eventually replace traditional mobile applications, the company recently hosted a symbolic app funeral in San Francisco that doubled as a developer day featuring industry partners like Stripe and OpenAI.

Photon provides a suite of developer tools, including a unified API, an extensible channel framework, a command-line interface, and an observability suite. These tools allow software engineers to deploy AI agents across iMessage, WhatsApp, Telegram, SMS, RCS, email, and voice. Since launching a managed subscription platform in April, Photon has attracted over 40,000 developer sign-ups. The startup reports a tenfold revenue growth over four months, a monthly messaging volume increase of 500%, and a customer churn rate under 3%.

For developers, the platform solves the friction of user acquisition by leveraging apps people already use daily. While Photon's open-source version on GitHub still represents 98% of its active use, the paid hosted version offers 99.95% uptime alongside SOC 2 Type II and HIPAA compliance. This enterprise-grade security allows developers to build agents for highly regulated sectors like healthcare and finance. The platform is free for up to 10 users, after which developers must transition to one of three paid subscription tiers.

A variety of companies are already building on Photon, including Rho, Corgi Insurance, and the dating platform Ditto. Additionally, Nous Research uses Photon as the default iMessage layer for its Hermes agent, and the technology serves as the underlying layer for Tencent's QClaw and NanoClaw. Looking forward, Photon CEO Daniel Tian envisions a shift toward agent-to-agent communication, where specialized AI assistants seamlessly coordinate with one another to complete complex user tasks.