Chert is a platform supported by Y Combinator that provides iMessage infrastructure for building and deploying AI to reach users at scale. Its main advantages include using the real iMessage protocol with a blue bubble user experience, which offers high response rates; avoiding filtering by carriers on A2P SMS, ensuring deliverability by managing sender identities properly; offering REST APIs and Webhooks for easy integration with teams' existing tools. Pricing information is not mentioned, and its positioning is to help GTM teams, leasing agents, etc., communicate and expand through iMessage.