PayPerByte MCP Server is a server that follows the Model Context Protocol (MCP), providing AI agents with direct access to the PayPerByte data marketplace. These data sources are cryptographically proven and their provenance is verifiable; the X-BYTE-Attestation receipt is used to prove delivery integrity—that is, that these bytes were indeed provided and attested by PayPerByte under the BYTE Library domain, but it does not mean that an independent data publisher signed them, nor does it mean that the data itself is correct.

Main capabilities

Discover data sources: list the PayPerByte catalog, or search publishers by topic (such as weather).
Counterparty screening: before settlement, screen a domain and receiving address, returning an ALLOW/WARN/BLOCK decision signed by the Merchant Screen Oracle, with an EIP-712 proof receipt attached. This decision does not constitute a guarantee of the correctness of the decision itself, nor does it observe or constrain the address you ultimately settle to.
Low-cost preliminary testing: obtain data such as weather, query today's earthquakes of magnitude 4 or higher, and pay real USDC at the price listed for each data source. Every response comes with a proof receipt, making it easy to experience "verify before acting" before spending higher fees.
Subscribe to data streams (testnet): for example, subscribe to an earthquake data source, automatically approving MockUSDC for continuous settlement on Arbitrum Sepolia.
Query the fact oracle (testnet): submit a signed EIP-712 question to a registered fact oracle publisher and obtain an on-chain signed answer with citations; currently no publisher is broadcasting, and this tool will time out until a publisher registers and broadcasts.

Two payment rails

x402 pay-per-use (byte_buy_data): Base mainnet (eip155:8453), using real USDC. Paid data sources settle real funds, each price is quoted in the 402 challenge, and is listed per data source under https://x402.payperbyte.io/feeds。示例：Merchant Screen Oracle returns a signed ALLOW/WARN/BLOCK check for the merchant domain and receiving address, backed by an EIP-712 proof signed over the exact response bytes, and runs before the agent settles an x402 payment to it. What is verified is authenticity and delivery integrity, not a guarantee of the correctness of the decision itself, nor does it observe or constrain the address you ultimately settle to. Please use a dedicated wallet that holds only the amount you plan to spend.
On-chain subscription/publishing/query layer (BYTE Library contracts + indexer): Arbitrum Sepolia testnet (chain 421614), using MockUSDC. The mainnet for this layer is limited by an external security audit (no audit completion time is currently available). Regardless of which rail is used for payment, the EIP-712 proof signing domain is always anchored at 421614.

A single PRIVATE_KEY serves both rails. Never reuse a wallet key that holds funds you cannot afford to lose.

How to connect

Connect the server to an MCP client (such as Claude Desktop). An example configuration is as follows (Linux path ~/.config/claude/claude_desktop_config.json, macOS path ~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "payperbyte": {
      "command": "npx",
      "args": ["-y", "byte-mcp-server"],
      "env": {
        "PRIVATE_KEY": "<your_private_key>"
      }
    }
  }
}

PRIVATE_KEY is optional: read-only tools can be used without it. Add it to enable subscription, publishing, purchase, and query functionality. See the repository documentation for environment variables.

Purchase decisions (POST oracle)

GET data sources only require a feed. Any data source whose method includes POST (for the live list see https://x402.payperbyte.io/feeds）将查询作为请求体接收，byte_buy_data will automatically switch the call from GET to POST. The verdict oracle data sources that return signature verdicts include: merchant-screen, address-reputation, sanctions-screen, pkg-verdict, reasoning-verdict.

Paid responses return a signature verdict, along with the inline verify-before-act result for the X-BYTE-Attestation receipt. Act only when verification.gatewayVerified === true—the receipt proves the gateway delivered these exact bytes, not that the data is correct.

Tools

There are 15 tools in total, divided into: discovery (read-only, no wallet required), subscription data feeds (PRIVATE_KEY required), and on-demand purchase (PRIVATE_KEY required).

Verify Before Act (ForeSeal)

The complete verify-before-act loop can be viewed with a single command, with no installation, registration, or wallet required (runs locally, no real USDC involved): it demonstrates an agent acting on real bytes and rejecting four attacks—tampered bytes, forged signatures, missing receipts, and forked signature domains.

The same primitive is provided in two packages that can be dropped into your own stack:

Kit — @payperbyte/sdk: the buyer verifies the receipt before acting.
Gate — @foreseal/gate: the seller stamps verifiable receipts on any x402 endpoint.

Two Modes: Subscription and Purchase

Purchase: zero-config, pay-as-you-go, already live under real settlement. Subscription: delivers every broadcast on an audit-restricted testnet tier. Choose based on your access pattern.

Fees and Licensing

The core npm package is free under the MIT license (see LICENSE). An optional paid kit is also available ($39): a buyer-side agent kit—an agent that purchases and verifies data sources, with configurations that can be dropped into Claude Desktop / Claude Code / Cursor, plus one free 30-minute readiness call. The npm package is always free under MIT; the kit sells the assembled configuration.

Other Information

No token.
Contract addresses are fixed in the bundled configuration; the npm release ships with ready-to-use defaults.
Links: payperbyte.io (PayPerByte homepage), x402.payperbyte.io/feeds (live data source directory), Model Context Protocol specification, MCP TypeScript SDK, gold-402 (live x402 service directory, PayPerByte is listed).

Limitations and Notes

What is proven is delivery integrity and authenticity, not data correctness.
The x402 rail uses real USDC on Base mainnet, involves real funds, and requires caution.
The on-chain subscription tier is currently only on the Arbitrum Sepolia testnet; mainnet is restricted pending an external security audit (audit status not yet available).
The fact oracle currently has no publisher broadcasts, and the tool will time out.

byte-mcp-server

About this tool