Photon raised $4.5 million in seed funding to expand its messaging infrastructure platform for AI agents across channels including iMessage, RCS, SMS, and WhatsApp. The round was co-led by Gradient and A*, with participation from Vercel, HongShan, Z Fellows, Llama Ventures, Karman, and angel investors.
Photon said it has powered chat experiences for more than 1 million end users in under a year.
The company also reported that revenue increased 10x between May and August, while message volume grew fivefold in the most recent month.
Photon plans to use the funding to scale iMessage business messaging for regulated industries, launch its Spectrum SDK, and onboard additional design partners.
The company is focused on solving a key distribution problem for AI agents: reaching users inside the messaging platforms they already use.
Photon said developers often have to maintain separate integrations for each channel, particularly because iMessage does not offer an official third-party API and other messaging platforms can impose changing access requirements.
Its Spectrum SDK is designed to give developers a single interface across iMessage, RCS, SMS, WhatsApp, and other channels.
Photon also launched what it described as the first mini-app API on iMessage in June, allowing developers to move beyond plain-text conversations and add buttons, forms, and live interfaces directly inside message threads.
The company has also expanded its integrations across the developer ecosystem.
Photon is the official iMessage adapter for Vercel’s Chat SDK and the default iMessage layer for Nous Research’s Hermes Agent.
It also integrates with Mastra, Convex, Render, and Telnyx.
Photon currently serves 50 paying customers and reported churn below 3%.
One customer, Ditto, has more than 140,000 active users and has sent more than 4 million messages through Photon.
Photon is SOC 2 Type II certified and HIPAA compliant.
The company was founded by Daniel Tian and Ryan Zhu and is headquartered in San Francisco.
KEY QUOTES:
“We started Photon because a friend could not tell our agent from a person in his own iMessage thread, and that told us where agents actually belong. Every team building an agent hits the same wall, which is that the audience is in messaging and messaging is closed. We built the layer that opens it, and the developers arriving without us asking are the signal that this was the missing piece.”
Daniel Tian, Co-Founder and CEO of Photon
“Photon is bringing AI capabilities to channels which have already onboarded more than a billion users, like iMessage and RCS. These channels offer consumers a far richer experience than traditional AI interfaces and developers the opportunity to meet their users where they already are. We are very excited about what Photon enables and the journey ahead.”
Vig Sachidananda, Partner at Gradient
