Silverback is a DeFi intelligence infrastructure protocol built on Base. It provides 21 paid API endpoints covering swap routing, yield optimization, technical analysis, token audits, whale tracking, arbitrage scanning, and backtesting. These endpoints are monetized through the x402 payment protocol, where agents and applications pay per call using USDC — no API keys or subscriptions required. The protocol operates the Silverback Facilitator, a zero-fee x402 payment settlement service supporting USDC transactions across Base, Solana, and SKALE. The facilitator is built on the official @x402/core SDK and is available for any x402 resource server to integrate. Silverback holds an ERC-8004 on-chain agent identity registered on both Ethereum and Base mainnets, providing verifiable reputation and a capability registry. Integration is available through an MCP server and npm SDK. $BACK is the native token of the Silverback ecosystem, launched via Virtuals Protocol on Base with a fixed supply of 1,000,000,000 tokens. There is no inflation mechanism — total supply is set at launch with no minting capability.