Etherscan: Build with AI for the onchain API

Etherscan is the block explorer. The Etherscan API is the same data behind etherscan.io, on 60-plus EVM chains, under one key. Build with AI is the agent layer on that API: MCP, a CLI, and installable skills. Docs: docs.etherscan.io/build-with-ai/introduction. Index: /llms.txt. Full dump: /llms-full.txt. Append .md to any page URL for raw Markdown.

Create a key at etherscan.io/myapikey. Free plan: 3 calls per second, 100,000 per day, most chains. Chain availability and PRO endpoints follow the API plan. GitHub org etherscan.

Two MCPs

The live-data server is https://mcp.etherscan.io/mcp. Streamable HTTP. Send the API key as Authorization: Bearer. Pass chainid for the chain (Ethereum is 1, Arbitrum is 42161). Docs say this is the only official Etherscan MCP. Marketplace clones are unaffiliated. Do not paste a key into those.

Docs MCP is https://docs.etherscan.io/mcp. No key. It searches the documentation so an agent can find the right module and action before it guesses. Pair them: docs MCP to pick the endpoint, live MCP to call it.

CLI

Install from the etherscan-cli repo. Homebrew tap etherscan/etherscan-cli/etherscan, or go install github.com/etherscan/etherscan-cli/cmd/etherscan@latest. Then etherscan login and etherscan whoami. JSON is the default output.

brew install etherscan/etherscan-cli/etherscan
etherscan login
etherscan account balance 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
etherscan --chain arbitrum account balance 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
etherscan tui

REST still exists

Agents sit on v2. Same key, switch chainid. First-call example from the docs:

curl --request GET \
  --url 'https://api.etherscan.io/v2/api?chainid=1&module=account&action=balance&address=0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045&tag=latest&apikey=YOUR_KEY'

Skills install from github.com/etherscan/skills. Orchestrator: npx skills add https://github.com/etherscan/skills --skill etherscan -g -a '*' -y. Flow, contract review, and transaction debugger are sibling folders in that repo.