How will agents pay for services, what do you think?

By now there are multiple ways for agents (or, machines in general) to pay for services, without them requiring an API-key, complicated signup-workflows or similar. For me personally, a few protocols spring to mind immediately: x402: Owned by the x402 Foundation (part of the Linux Foundation), formerly owned and developed by Coinbase in early 2025. The premise is simple: On a payable resource the seller returns an error 402 with the amount, payTo-address, coin and chain that is required to pay this resource. Buyer signs a payment-authorization for exactly this amount of money, optionally hands it over to a facilitator who approves the cheque and, in return, the buyer gets access to the data. It's crypto-centric (mostly based on stablecoins like USDC), but exactly because of this reason it's the most used protocol for machine-to-machine payments right now: It's chain-independent, so a seller can request ANY currency they want, and needs no centralized company that approves or denies transactions. You can even be your own facilitator, if you want. Because of the crypto-base it supports micropayments with under a cent in volume, as the otherwise too expensive credit-card-fees don't apply here. x402 already has >80.000 publicly listed endpoints (tracked by my own service that I provide in the ecosystem, but that isn't the topic here) and adoption is rising steadily, with the payment volume of mid-August already surpassing the volume of the whole of July. Big companies like Cloudflare have already publicly adopted x402 as a native way to monetize websites & services, with convenient libraries to implement the protocol with just a few clicks. To date, way over $50.000.000 in payment volume have been settled through x402, most of it far under $1 per call. Machine Payments Protocol (MPP) Developed by Stripe & Tempo, this protocol is also based on the 402 errorcode, however it's supposed to be payment-method-agnostic; The same mechanism can transport stablecoin-payments or credit card payments (via Stripe for example, for obvious reasons). It even offers compability with x402 endpoints, so it doesn't cannibalise it, but rather offers a different FIAT vector for the same payment rail, that x402 simply does not support. However: Because of the high fees of FIAT credit-card-settlements, the same micropayments as with stablecoins aren't really feasable here. The protocol is much younger compared to x402 (release in March 2026), so it's still much smaller, however it's growing fast. OpenAI, Anthropic, Parallel and Cloudflare (again) already support the protocol natively. L402 Developed by Lightning Labs, this is the much older brother to x402. It's a similar protocol in function, however it is entirely Bitcoin-centric (to be exact: Bitcoin Lightning Chain). Lightning Labs picked up the development again in 2026 and started to push the protocol out more aggressively to capture the rising agentic economy boom. They've already published new libraries for easy implementation, but its overall adoption is much smaller compared to x402. And, as I said, it's fully Bitcoin-centric and not chain-agnostic like x402, so I personally don't believe that this protocol will thrive in the future. People (and agents) like to have options after all :) What's your opinion, what protocol will eventually succeed in taking the market? Or maybe a symbiosis of multiple? Have there been any that I missed? I'm eager to hear your opinions.