402index
402index is a directory of paid APIs for AI agents. Its own site describes it as protocol-agnostic, indexing endpoints on the L402, x402 and MPP rails, searchable by an agent through an MCP server and a skill file it publishes.
402index indexes paid endpoints across three rails — L402, x402 and MPP — and publishes them as a directory an agent can search, filter and pay through. Its site offers the directory as an MCP server and as a skill file an assistant can read.
It probes the endpoints it lists and publishes a status for each host in its own vocabulary. That vocabulary is 402index's, and the words in it are not the capture-time words probe402 publishes; a reader comparing the two is comparing two instruments, and the entry on discovery says what a directory listing does and does not establish.
probe402 is itself listed on 402index, and the listing was claimed by serving a verification file at a well-known address, which is the mechanism 402index publishes for an operator to prove a domain.
→ probe402 names the graders whose payments do not count toward its own demand reading on the method page, and this is one of them.