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The problem

Agent-to-agent and agent-to-API payments require too much blockchain knowledge. Developers who want to charge for an API or pay for one should not need to understand gas fees, transaction signing, or chain-specific quirks. Existing payment libraries tend to be monolithic, opinionated about which chain to use, and tightly coupled to a single wallet or provider.

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The approach

Faremeter uses HTTP as the payment layer. When a server requires payment, it responds with 402 Payment Required. The client handles the payment transparently and retries the request. No special protocols, no WebSockets, no SDKs on both sides. Just HTTP. 
Client                    Server                  Facilitator
  |                         |                         |
  |--- GET /resource ------>|                         |
  |<-- 402 + requirements --|                         |
  |                         |                         |
  |  (sign payment locally) |                         |
  |                         |                         |
  |--- GET /resource ------>|                         |
  |    + X-PAYMENT header   |--- verify + settle ---->|
  |                         |<-- confirmation --------|
  |<-- 200 + data --------- |                         |

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Design principles

Composable — Use @faremeter/rides for the simplest path, or compose @faremeter/fetch with specific wallet and payment packages for full control. Every package works independently. Unopinionated — Faremeter does not prescribe a chain, wallet, or framework. Plug in Solana, EVM, or both. Use Express, Hono, or bring your own. Swap wallets without changing business logic. Standards-agnostic — Built on the x402 protocol, compatible with Coinbase x402, Cloudflare Pay-Per-Crawl, and L402. New standards can be supported through the payment handler plugin interface. Pragmatic — Faremeter uses facilitators to abstract blockchain complexity. Merchants never touch private keys or gas fees. Clients sign locally; facilitators settle on-chain.

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Architecture

@faremeter/rides          (high-level, zero-config)
    |
@faremeter/fetch          (pluggable fetch wrapper)
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@faremeter/payment-*      (chain-specific payment schemes)
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@faremeter/wallet-*       (wallet adapters for signing)
Each layer can be used independently. rides composes the layers below it automatically. Developers who need control drop down to fetch and wire up their own handlers.