Amazon

Amazon holds 40% of US e-commerce by Max Thilén's February 2026 count, and it has declined both protocols built for agent-driven shopping: the «Agentic Commerce Protocol» from OpenAI and Stripe, and the «Universal Commerce Protocol» that Sundar Pichai launched at NRF 2026 with Shopify, Walmart, Target and more than sixty other organizations. Amazon enforces that refusal. It blocked OpenAI's crawlers and withdrew 600 million products, and in September 2026 it blocked «Muse», Meta's assistant, from its storefront with a message calling the access an unauthorized agent. Ryan Sarver read that incident as the opening of platform wars in which customers of both companies lose the use that matters most: buying.

What Amazon builds instead is proprietary: «Rufus AI» (300 million users, a reported +60% conversion), Alexa+ for voice commerce, and «Buy for Me (système propriétaire)», which purchases from competitors inside the Amazon app. Thilén describes the resulting market as a triptych, with Amazon on one side and Google's UCP and OpenAI's ACP on the others.

The closure is selective. In August 2026 Amazon sat on the technical steering committee that published «Agent Plugins» 1.0.0 alongside Cursor, Microsoft, OpenAI and Vercel, a vendor-neutral packaging format. Open at the packaging layer, closed at the transaction layer.

Two Amazon voices arrive here on other terms: «Werner Vogels», arguing for AI inside the human loop, and «Fran Soto», writing on developer taste. Philippe Corrot notes that the marketplace model went from 5% of Amazon's activity to more than two thirds.