Agent API Secured On-Chain

Private keys stay in browser memory. Revokable sub keys are registered on Near smart contract, enforcing spending limits and allow lists.

Smart Contract Account Abstraction Protection

Every offline transaction requested by an agent is validated by a Near Smart Contract before execution. This contract acts enforces your customized spending limits, daily caps, and allow lists.

Once the smart contract verifies the transaction against your security rules, it commands the Near MPC (Multi-Party Computation) network to generate the final cross-chain signature. This architecture enables trustless automated trading across multiple blockchains.

Browser

Private Keys

→

Server Processor

Encrypted Sub Keys

Smart Contract

Spending Rules

→

Near MPC

Multi Chain Signer

x402 Payments Client and MCP Server

Holder implements the x402 open payment standard as both a client and an MCP server, letting any AI agent - from Claude to GPT and 100s more — pay for API calls, on-chain actions, and data services without ever touching your master key.

Agents discover the holder_pay MCP tool automatically. Each payment is scoped to a sub-key with hard-coded spend limits, enforced by the smart contract before the transaction ever reaches the network.

                        // Agent calls Holder MCP server to execute an x402 payment

                        const result = await mcp.callTool("holder_pay", {

                          to: "0xApiProvider...f3",

                          amount: "0.10",

                          token: "USDC",

                          chain: "base",

                          memo: "inference:gpt-4o-call-8821",

                        });