what AI agents pay per API call: x402 vs L402 vs MPP, from probing 458 endpoints

satbotly — Tue, 10 Nov 2026 10:04:23 +0000

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.