Karla Barker 
The software wallet shift
For years, crypto firms looked for the next billion users among the unbanked or people fleeing inflation. The next wave may instead be software. AI agents can now shop, call APIs, and pay for services on their own, and a growing list of companies wants to be the payment layer underneath.
Coinbase says its x402 protocol has handled more than 165 million payments worth about $50 million. Lincoln Murr, Coinbase’s head of AI product, estimates roughly 99% of those payments used USDC. That gives stablecoins a measurable early lead in a market built for machines.
Cloudflare, MoonPay, Circle, and Mastercard are also building. Cloudflare recently announced wallets and a pay system for agents. MoonPay’s PayBox connects agents to cards and crypto wallets. Circle is testing nanopayments that batch tiny USDC transactions and settle them later onchain.
Cards are not done yet
Stablecoins have an edge for small digital purchases, but cards remain strong for bigger transactions. Mastercard’s Agent Pay for Machines lets an owner set spending limits and approved sellers in advance. The seller can be paid in fiat or a stablecoin, even if the buyer used a different method.
Card networks bring existing merchants, credit, refunds, and dispute systems. For a $500 hotel booking, that matters. For a 30-cent API call, it may not.
Guardrails before trust
The harder problem may be controlling the agent, not moving the money. If an agent misunderstands an instruction or follows a malicious prompt, the payment rail still worked. Companies are responding with limits: capped balances, approved seller lists, and human approval for sensitive actions.
Turnkey’s CEO compared this to early self-driving cars. Agents need a human with hands near the wheel until they prove they can be trusted with more freedom. For very small payments, sellers may rely on reputation instead of costly fraud protection. For larger payments, escrow and refunds become important.
Coinbase says x402 is focused on microtransactions partly because an agent that wastes ten cents is not worth litigating. But buying flights or booking travel needs stronger protections, and crypto developers are adding escrow and partial refunds.
An early lead, not a finished race
Stablecoins have real usage, but not everything is settled. Cloudflare’s wallet system is not fully live. Mastercard’s product is in early access. MoonPay has not shared adoption numbers. Some of Coinbase’s transaction count may include testing and incentive activity, not just production use.
Agents still face a basic hurdle: getting money into their wallets in the first place. Coinbase is looking at fiat onramps to solve that, and wants agents to eventually set up wallets on their own after a user signs in.
The likely outcome is a mixed system. Buyers, sellers, and agents may use different rails depending on the size and type of purchase. Stablecoins have the early network effect among machine payments, but cards still have wide acceptance. The next few months will show which holds up under real agent activity.