what AI agents pay per API call: x402 vs L402 vs MPP, from probing 458 endpoints
I run a small free directory called SatBotly that lists things an AI agent can pay for on its own. The part people ask about most is the pay-per-call APIs: endpoints that answer with an HTTP 402 and name a price for one request, over x402 (usually USDC), L402 (Lightning), or MPP.
Marketing pages are a bad place to read those prices. On October 17 and 18, 2026, I sent one unpaid request to each endpoint in the directory and read the amount from the 402 challenge itself. I never paid an invoice. The directory only keeps endpoints that answered with a valid 402. This write-up is about that set of 458, not about a wider candidate pool, whose size I am not publishing because it is not in the public data.
As of November 5, 2026, the split is 301 x402, 121 L402, and 36 MPP.
The medians
| Rail | Endpoints | Median price per call | How the price was read |
|---|---|---|---|
| x402 | 301 | $0.015 | USDC amount in the unpaid 402 payment challenge (first accepted option) |
| L402 | 121 | 10 sats (about $0.008) | amount decoded from the Lightning invoice in the unpaid 402 |
| MPP | 36 | $0.005125 | USDC.e amount in the unpaid MPP 402 challenge |
In short summaries I round the last two to $0.008 and $0.005. The L402 dollar figure uses an approximate sats-to-USD rate from October 15, 2026 (about $0.000815 per sat), which the dataset marks as being for sorting and display. The native L402 number is 10 sats.
Across all 458 endpoints, the median was $0.01. 238 of them (52%) asked for a cent or less. 63 of the 121 L402 endpoints asked for 10 sats or less. 291 of the 301 x402 endpoints priced the call in USDC on Base.
Why I am not quoting an average
The mean of this set is about $9.43, which is a useless number here. A handful of 402s are not micropayments for a small API call. The highest I saw was $2,950, for a jewelry purchase on an x402 endpoint. Another, on MPP, asked for $1,024 to fetch JSON results from a Dune execution. A third, on L402, asked for about $163 for a consulting integration. Those are real unpaid 402 amounts, but they should not set your mental model for what "an agent API call" costs. That is why I publish medians.
I also looked at categories with at least five endpoints. The lowest median was data/science, at about $0.0024, and the highest was guides, at about $3.00. I would not lean on that comparison: both categories are small, and the seven guide endpoints are paid L402 guides from a single provider.
How the probes worked
The method is the same one documented at satbotly.com/method.
For L402, the unpaid request comes back with a Lightning invoice inside the 402. I decode the invoice amount and never pay it. For x402, I read the USDC amount in the 402 payment challenge, using the first accepted option. For MPP, I read the amount in the MPP Payment challenge (USDC.e, 6 decimals). 262 of the probes were GET and 196 were POST, matching whatever the endpoint expects. Every listed endpoint has a probe timestamp of October 17 or 18, 2026, and a probe status of 402.
I did not buy a sample response to confirm the endpoint delivers after payment. A 402 with a price is evidence of what was asked, not a receipt for a successful purchase. Prices can change. This is a snapshot.
The rest of the directory
SatBotly also lists 199 agent wallets, 331 payment services, and 231 merchants checked for Bitcoin acceptance. Those verdicts (YES, KINDA, or NO) come with a source quote from the project's own page.
One number that comes up a lot in Lightning agent setups: 38 of the 199 wallets list NWC (Nostr Wallet Connect) among their payment rails. 120 list Lightning. Of the 231 merchants, 153 were a clear YES for Bitcoin, 65 were KINDA (for example, Bitcoin only via a gift card), and 13 were NO.
If you just want to see what a 402 looks like, there is a free demo at satbotly.com/try402. It returns an HTTP 402 with a Cashu (NUT-24) request for 21 test sats. No real money moves.
Caveats
This is a small free project, not a comprehensive study of "the agent economy." The 458 figure is the set that answered a valid 402, not a success rate on every URL I ever tried. There was one probe per endpoint, on two days in October; the directory snapshot is dated November 5, 2026. L402 dollar amounts use an approximate rate. The endpoints are what I could find and verify from public lists and live probes, not a random sample. Sponsors cannot buy a verdict, rank, price, or proof quote, and browsing the data is free.
If a price or verdict looks wrong, tell me and I will fix it. The live lists are at https://satbotly.com.