Public data, free to use
Who sells to AI agents, and what they take.
A dated list of the services and standards that sell to software agents, what each one accepts, and where that answer came from.
For a developer choosing a payment rail, a buyer checking a vendor's claim, or anyone who wants a straight answer instead of a pitch.
Loop XXI builds on Bitcoin and Lightning. This list also covers services on rails we do not use.
The list
8 entries, each read from its own source on the date shown.
| Service | What it is | Accepts | Status | Source |
|---|---|---|---|---|
| x402x402 Foundation · protocol | An open standard that turns HTTP 402 into a payment handshake, so a server can charge per request. | whatever networks the seller enablesThe standard is network-neutral. The seller chooses which networks and payment schemes to accept, so the standard itself names no asset. | LiveThe project publishes its own rolling transaction, volume, buyer and seller totals. | x402.orgchecked |
| Coinbase CDP x402 facilitatorCoinbase · service | A hosted facilitator that verifies and settles x402 payments on a seller's behalf. | USDC, other ERC-20 tokens on EVM networks, SPL tokens on SolanaIts documentation calls USDC the most common asset and says sellers may accept other tokens. | LiveIts documentation reports more than 100 million x402 payments settled across Base and Solana. | docs.cdp.coinbase.com/x402/welcomechecked |
| Machine Payments Protocol (MPP)co-authored by Tempo and Stripe · protocol | An open standard for machine-to-machine payments over HTTP 402, published as an IETF draft. | stablecoins, cards, bank transfersPayment methods published so far cover Tempo, Stripe, EVM, card, Lightning and Solana. Each rail maintains its own method. | LiveStripe documents charging for tool calls and HTTP requests over MPP. | mpp.devchecked |
| Agent Payments Protocol (AP2)FIDO Alliance · protocol | An open protocol for agent commerce, published as an extension to the Agent2Agent protocol. | cards, x402Taken from the protocol's own sample flows, which cover cards and x402 with and without a human present. | Spec publishedA v0.2 specification and sample flows are published. | ap2-protocol.orgchecked |
| L402Lightning Labs · protocol | An open protocol for paying for API access over the Lightning Network with a macaroon and an invoice. | Lightning (BOLT11 invoices)The credential is a macaroon bound to the invoice payment hash, so no account or session is needed. | Live19 paid Lightning transactions across 8 L402 services, cumulative to 27 October 2026, seen through one public proxy. Status reported by l402.space. | github.com/lightninglabs/L402checked |
| Stripe agentic commerceStripe · service | Card payments and machine payments for agents, including a wallet an agent can pay from. | cards, machine payments over MPP and x402Its documentation lists an agent wallet, embedded commerce, and charging for tool calls and HTTP requests. | LiveIts documentation warns that availability, launch stage and supported countries vary by integration. | docs.stripe.com/agentic-commercechecked |
| SkyfireSkyfire · service | An agent identity token plus a wallet and checkout, so an agent can log in and pay at a merchant. | Visa, Mastercard, Discover, USDCIts site lists these card networks and USDC for agent checkout. | LiveIts site presents agent checkout as available now and offers a launch control; it publishes no transaction volume. | www.skyfire.xyzchecked |
| TempoTempo · service | A payments chain for stablecoins, with machine payments supported as a first-class product. | stablecoins on Tempo (TIP-20 tokens)Its documentation describes stablecoin accounts, routing and machine payments, and MPP's Tempo method signs TIP-20 transfers. | LiveIts documentation describes production products alongside a testnet for development. | docs.tempo.xyzchecked |
How to read a row
- Live means the source shows the service open today: the operator says it settles payments, or a public record shows settled payments. It does not mean we tested it.
- Spec published means a specification and docs exist, and the source makes no settlement claim.
- Unknown is the honest answer when the source did not say. We leave the gap rather than filling it.
- Accepts is what the source says the service takes. Where a seller chooses, the row says so instead of picking one asset.
What this list is not
- Not a payment test. Nobody at Loop XXI made a payment to any of these services, so nothing here is verified by settlement.
- Not a complete market. It lists services we could read a public source for, not every service that exists.
- Not a ranking. Rows are ordered by kind, then by reach, not by quality or price.
- Not pricing. Fees, minimums and settlement times change often enough that a static page would be wrong.
- Not a claim that a listed service is open to new sellers. Availability varies by country and by account.
Download
- Directory (JSON)Every row with its source and checked date, in the same order as this page.
- Counts and daily snapshotHow many endpoints each protocol lists, and the paid traffic one public proxy observes.
No account is needed. The file is served from this site and matches the table above row for row.
Corrections
If a row is wrong, the fix is a new source and a new date, not a quiet edit. Each change shows up in the file's history with the date it was checked.