Live · Y Combinator Launch · May 2026
TL;DR — Chert is the API for iMessage. Send messages, receive replies, and run real conversations on the channel people actually trust. We're launching publicly today alongside our YC batch.
The channel matters as much as the message
iMessage is one of the most-used messaging products in the United States. People open it every day to talk with friends, book appointments, coordinate plans, and have actual conversations. It's the channel reserved for people you know.
For businesses, it's been almost impossible to automate. Anyone trying to build on iMessage has had to spin up phone lines, manage devices, monitor line health, and bolt the whole thing back into their existing stack by hand.
That's the gap we're closing.
What we built
Chert lets teams build agents and applications that send and receive iMessages directly through our API. A few things change once you're on a real-trust channel:
Higher trust, higher visibility. Green-bubble SMS and RCS get filtered, batched, and ignored. Blue bubbles get opened. People read iMessages because the surface itself implies someone they know wrote them.
Conversations that feel like conversations. Typing indicators, reactions, stickers, attachments, images, video — the expressivity of the channel matches how humans actually talk. Email and SMS can't do that. iMessage does it natively.
Faster response loops. Because iMessage is the channel users already check constantly, the back-and-forth is continuous. A reply lands in seconds, not days. Threads stay alive across hours and weeks the way real relationships do.
We integrate natively with calendars (Calendly, Cal.com), CRMs (HubSpot, Salesforce), and the rest of your internal tools — so the conversations you run on iMessage stay structured, logged, and connected to the systems your team already uses.
Who it's for
We're working with three kinds of teams today:
- B2C startups who want every signup, onboarding step, and reactivation to feel personal — not like a no-reply email from a marketing automation tool.
- Customer experience teams ready to retire the floating chat widget and meet customers in the inbox they actually answer.
- AI agents that need a channel where the user is willing to keep talking. iMessage is that channel.
What we've seen
We've spent the last several months running Chert in production with early customers. The pattern is consistent across every use case: response rates are an order of magnitude higher than email, and customers stay engaged across multi-turn threads instead of dropping off after one reply.
Trust isn't a marketing word here. It's the technical primitive iMessage gives you for free.
The thing every business communication channel before it has been trying to claw back since the day spam was invented — iMessage starts with it.
The ask
If you're building something that touches B2C messaging, customer experience, or AI agents — and you want to talk to your users on iMessage instead of through another browser tab — we'd like to talk to you.
If you have a use case for iMessage we haven't thought of yet, we'd especially like to talk to you.
You can reach us through our contact page, or book a call directly. The full YC launch is live here.
— The Chert Team