October 2026

Why Amazon, eBay and other marketplaces block AI shopping agents

Marketplaces block AI agents for two kinds of reason. The ones they give are fraud, security and mistaken orders. The ones underneath are advertising, shopper data and who owns the customer. An agent that shops for someone skips the sponsored results, sees prices across every store, and leaves the marketplace with nothing but the order. In 2026 Amazon, eBay and others decided they would rather say no, or say yes only to agents they approve.

A year of blocks

When	What happened
July 2025	Cloudflare starts blocking AI crawlers by default for new sites, and lets sites charge crawlers per page. Shopify stores add a note to robots.txt that buy-for-me agents may not check out without a person’s final review
October 2025	Cloudflare, Visa and Mastercard announce a way for shopping agents to prove who they are, built on Web Bot Auth
November 2025	Amazon sues Perplexity over its Comet browser agent
December 2025	eBay adds a “Robots & Agent Policy” to its robots.txt
February 20, 2026	eBay’s user agreement bans buy-for-me agents and LLM-driven bots that place orders without human review
March 2026	A federal court orders Comet off Amazon while the case runs
August 4, 2026	The Ninth Circuit lifts that order. The case itself goes on
September 20, 2026	Amazon cuts off Meta’s Muse agent, launched 12 days earlier
October 2026	Retailers split: QVC lets agents buy, Kate Spade lets them browse only, Kohl’s and Amazon keep them out

Amazon and Perplexity

Comet is a browser with an agent built in. Ask it to buy something on Amazon and it signs in as you, finds the item and checks out. Amazon says the two companies agreed in 2024 to pause agentic shopping, and that Perplexity turned it back on with Comet presenting itself as an ordinary Chrome browser. Amazon sued under the Computer Fraud and Abuse Act and won a preliminary injunction in March 2026.

In August the Ninth Circuit reversed it. Because Comet only acts when its user tells it to, the court said it is the user, not Perplexity, who is accessing Amazon, and the user has permission to be there. It was the first appeals ruling on an AI agent acting inside someone’s own account, and commentators read it narrowly: this agent, this site, this record. It doesn’t give agents a general right to use any site, and Amazon’s claims under its own terms are still open.

Amazon and Meta’s Muse

Meta launched Muse on September 8, 2026, as a personal agent that can open a browser, fill in forms and check out. Twelve days later Amazon began showing Muse users a notice that an unauthorized AI agent breaks Amazon’s Conditions of Use, which they had agreed to. Amazon said it had asked Meta to leave Amazon out, and that Muse doesn’t identify itself when it browses. Meta says Muse never sees passwords or card numbers.

With the computer fraud route weakened by the Perplexity ruling, Amazon now leans on its contract with its own customers. That is the same move eBay made in its user agreement.

eBay writes it into the contract

eBay’s rule is short: checkouts are for people. Its user agreement, in force since February 20, 2026, bans buy-for-me agents, LLM-driven bots and any flow that places an order without a person reviewing it, unless eBay has given permission first. eBay gave auction manipulation, fraud and mistaken orders as reasons. It left a door open for approved partners, and still lets AI search and user agents read its listings.

The reasons they give

Fraud. A bot that checks out looks much like the bots that buy up stock or test stolen cards, and retailers’ fraud systems were built to stop it.
Security. A browser agent that signs in as you has your session, and sometimes your password.
Mistakes. When an agent buys the wrong size or the wrong quantity, the return and the complaint land on the store.
Disclosure. Amazon’s main complaint about both Comet and Muse was that they didn’t say what they were.

The reasons underneath

Advertising. Amazon reported $47 billion in advertising revenue in the first nine months of 2025. Sponsored results only pay when a person looks at them, and an agent doesn’t.
Data. A marketplace learns from every search, view and abandoned cart. When an agent does the browsing, the marketplace sees only the final order.
The customer. If people start their shopping in ChatGPT, Gemini or Muse, the marketplace becomes a supplier to the assistant. Amazon, which keeps outside agents out, runs its own: Rufus and Buy for Me.

Where it is going

The direction is from open or blocked to approved. Shopify now points agents to endpoints built for them, and asks the buyer to approve each payment. Walmart and Etsy sell inside ChatGPT through OpenAI’s Instant Checkout. Visa’s Trusted Agent Protocol and Mastercard Agent Pay let a shop check that an agent is registered before it takes an order, and Web Bot Auth lets any bot sign its requests so sites can tell it from an imitation.

Agents that identify themselves and go through the front door will get further than ones that pretend to be a browser. But approval is given one partner at a time, and the big listing sites for homes, jobs and local services haven’t offered it at all.

What it means for listings

Shopping gets the headlines because there is a checkout to fight over. For homes, jobs and local services the problem comes earlier: an agent can’t read the listing, and when it can, it has no way to ask the owner a question. That is the part Openpath works on. It lists only what owners send or allow to be read, and puts an inbox on every listing so the agent can write to the owner. See which marketplaces block AI agents for site-by-site rules.

Questions people ask

Why did Amazon block Perplexity?

Amazon says Comet shopped in customers’ accounts without permission and hid that it was an agent. Perplexity says Comet acts for the user, who is allowed on Amazon, and that Amazon wants to protect its advertising. The Ninth Circuit sided with Perplexity on the injunction in August 2026; the lawsuit goes on.

Is it legal for an AI agent to shop on Amazon?

No court has settled it. The Ninth Circuit found Amazon unlikely to win its computer fraud claim against Comet, but Amazon’s Conditions of Use still forbid unauthorized agents. This post isn’t legal advice.

Will marketplaces let AI agents in eventually?

Most seem headed for approved access: agents that identify themselves, use the marketplace’s own API or protocol, and ask the buyer before paying. Amazon is the main holdout so far.

Sources

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