Circle switched on Arc with Visa and Mastercard among its validators, and Alchemy’s AgentCard now pays with one-time Mastercard credentials

Circle switched on the public mainnet of Arc on 16 September 2026. It is a Layer 1 blockchain whose fees are paid in USDC, the stablecoin Circle issues, of which more than $74 billion is in circulation [1] [2]. BlackRock, DTCC, ICE, Mastercard, Visa, Standard Chartered and SBI Group are among the founding validators, the validator set is permissioned, and more than 100 institutional and ecosystem builders were live on day one [1] [2].

Circle is selling the chain to agents as hard as to treasurers. Arc Portal lets a person fund an agent wallet, set spend limits and hand it tasks onchain, the release says [1], and Decrypt lists agent wallets, spending limits and nanopayments among what shipped [2]. Circle also says USDC carries 98.8% of agent-driven transaction volume, a figure Decrypt reports it took from Dune [1] [2]. Jeremy Allaire, Circle’s chief executive, said in the release: “The agentic economy and the onchain economy are not two different revolutions; they are the same economy seen from two sides” [1].

Alchemy’s AgentCard now carries Mastercard credentials

A day later Mastercard lent its card rails to a product that also hands agents a stablecoin wallet. Alchemy said on 17 September 2026 that AgentCard, its payments and identity kit for AI agents, now supports Mastercard credentials through Mastercard Agent Pay [3] [4]. An agent set up on it gets a dedicated email address, a phone number, a stablecoin wallet and one-time-use Mastercard credentials. The credentials are tokenised and linked to the user’s existing Mastercard, so its rewards and credit line carry over [3]. Users and issuers set the agent’s purchase limits and allowed merchant categories, and AgentCard is built to support Verifiable Intent, Mastercard’s record of what the user approved [3] [4].

The release splits the job in two. The stablecoin wallet is for the new agent payment protocols, and the card credential is for “the many online merchants that still rely on traditional credit card rails” [3]. Alchemy’s own post on X was shorter: “The checkout button is dying” [4]. PYMNTS noted that Alchemy wired AgentCard into Visa Intelligent Commerce in June [4].

Cloudflare blocks the agent at the ad

Since 15 September 2026, Cloudflare has offered new domains that earn money from ads a preset that allows search crawlers, refuses AI training and blocks agents on any page detected serving an ad [5] [6]. The agent category covers user-directed agents visiting for a person, such as chat fetch bots and browser-use agents [5] [6]. Bryan Becker wrote in Cloudflare’s announcement that “Ad revenue depends on a human actually seeing the page”, and that agents “fetch the page with nobody there to see the ads” [5].

Fewer than 1% of Cloudflare sites block search bots and 17% block training, the company said [5] [6]. There is no Disallow setting for agents yet, only a block [5] [6]. PYMNTS pointed out that the block lands hardest on the review sites and comparison guides a shopping agent reads before it reaches a checkout [6].

Alchemy says an agent on AgentCard can now pay anywhere Mastercard is accepted online [3]. Will the review site it reads first let it in, or send it a bill for the visit?