Who's Building AI-First Products These Days?

We all love Microsoft, Stripe, and Zapier for adding AI to their existing lines of products. But I'm wondering, what are some examples from the last couple of years that are truly AI-first? I mean, who's building their UI (GUI or API) specifically around AI? What are the products that simply weren't possible before the era of general AI and are now doable? I'm keen to learn about both well-established startups that are already pulling in revenue and traction, and the new guys on the block who are totally revolutionary but still looking for product-market fit.