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APIs that charge by rail · weekly cut 2026-10-27

Weekly count of the APIs that charge on each agentic payment rail, computed from LupaRiel's public catalog. Every number comes from the CSV and JSON downloads.

Cut ISO week 2026-W44 /rails-index/semanal/2026-10-27.csv /rails-index/semanal/2026-10-27.json CC BY 4.0 Versión en español

x402
434
+153 vs 2026-10-09
AP2
127
0 vs 2026-10-09
ACP
87
0 vs 2026-10-09
MPP
168
+22 vs 2026-10-09

APIs that charge, by rail

An API on several rails counts once per rail. Status is the entry's status on that rail.

Rail APIs Production Pilot Announced Per-call price Median entry RRL 3 / 2 / 1 / 0 Change
x402 434 433 0 1 329 / 434 US$0.01 267 / 84 / 67 / 16 +153
AP2 127 13 22 92 no per-call price — 0 / 35 / 91 / 1 0
ACP 87 38 20 29 no per-call price — 0 / 54 / 29 / 4 0
MPP 168 168 0 0 55 / 168 US$0.01 13 / 27 / 97 / 31 +22

Change vs Rails Index 2026-10, cutoff 2026-10-09. AP2 and ACP charge per checkout, the amount is set by each merchant: there is no per-call price and no estimate. Unique APIs in the catalog: 771, 770 on at least one payment rail.

Download CSV · 2026-10-27.csv Download JSON · 2026-10-27.json

Entries that joined or left each rail

The previous reference is a monthly edition, so this cut only reports the change in counts. From the next weekly cut on, each rail lists the entries that joined or left.

How it fits the monthly Rails Index

Same definition of APIs as the monthly Rails Index. From the November 2026 edition on, each monthly edition lists every weekly cut of the month with its per-rail counts, and when a weekly cut and the edition come from the same data commit their numbers must match. Rails Index.

Methodology

  • What "charges" means. An API charges on a rail when its catalog entry has evidence on that rail (the rail table in the research). Same definition as the APIs count in the monthly Rails Index. An API on several rails counts on each.
  • Source. The catalog published at /catalog.json as of commit 8931981, plus the RRL file from probe rrl-2026-10-25 (2026-10-25 11:04 ART). Nothing is added by hand.
  • Status. The entry's status on that rail, the most advanced among its rows for the rail (Production > Pilot > Announced).
  • RRL. Rail Readiness Level of the entry on that rail. RRL methodology.
  • Per-call price. Same rule as the Rails Index: the first $ amount per call or without a unit. AP2 and ACP have no per-call price.
  • Change. Against the previous weekly cut, by entry slug. When the previous reference is a monthly edition, only counts are compared.
  • Reproducible. npm run corte-semanal -- --cut 2026-10-27 on that commit gives the same file. A published cut is never rewritten.

License and citation

Data under Creative Commons Attribution CC BY 4.0. Suggested citation:

LupaRiel, weekly cut 2026-10-27: APIs that charge by rail. https://lupariel.com/en/rails-index/weekly/2026-10-27/. CC BY 4.0.

Weekly cuts