Onchain Data MCP Server

onchain-data-mcp

Give your AI assistant live blockchain data: wallet balances, payments, prices, scam checks and more. Free to start, no sign-ups needed.

The Claude Desktop button downloads a file you double-click; it has everything inside. The Cursor and VS Code buttons only add the settings, so install the program first.

onchain-data-mcp is one small program that lets AI apps like Claude, Cursor and VS Code read the blockchain. It works with Ethereum, Base, Arbitrum, Optimism, Polygon, Avalanche, BNB Chain, Robinhood Chain and Solana.

Behind the scenes it asks about 30 data services ("providers") for you. If one is slow, busy or down, it quietly asks the next one. Free services come first, so you can start without paying anything and without any sign-ups.

A few words you will see here:

• MCP is a standard way for AI apps like Claude to use outside tools. This program is an "MCP server": a tool your AI app can use.
• API key is a free password a data provider gives you when you sign up. You don't need any to start. Adding a couple makes answers faster and more complete.
• Wallet address is the public "account number" of a crypto wallet, like 0xd8dA…6045 or 7xKX…9sHc.

Contents

• What you can do
• Quick start
• Connect to AI apps
• The dashboard
• Password and keys
• Data providers
• Available tools
• Real-world examples
• Running it for others
• Troubleshooting
• FAQ
• For developers · Security · License

What you can do

Ask your AI assistant questions in plain words. It picks the right tool and gets the answer.

• Check wallets. See what coins and tokens a wallet holds, on every chain at once. "What does wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 hold?"
• Confirm payments. Check that a customer really paid the right amount of USDC to the right address. "Did transaction 0xabc… on Base pay 25 USDC to my shop address?"
• Stay safe. Check if a token is a scam, if an address is on a sanctions list, or if a stablecoin is losing its value. "Is this token on Solana a honeypot?" · "Is USDT still worth one dollar?"
• Follow the money. Get transaction details, fees, and a bank-style statement for a wallet. "Show me last week's incoming payments to my wallet, with their dollar value."
• Prices and swaps. Get token prices from several sources, past prices, and swap quotes. "What's the best price to swap 1 ETH to USDC on Arbitrum right now?"
• Tokenized stocks. Look up stock tokens on Robinhood Chain and their prices. "What is the price of the Tesla stock token on Robinhood Chain?"

It only reads data, with one exception: it can send a transaction that you already signed yourself in your own wallet. It never holds your keys and can never move your money on its own.

Quick start

Three steps, about five minutes.

1. Install the program

Pick one. You only need to do this once.

Mac or Linux (open the Terminal app and paste):

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/madlabs-tech/onchain-data-mcp/releases/latest/download/onchain-data-mcp-installer.sh | sh

Windows (open PowerShell and paste):

powershell -ExecutionPolicy Bypass -c "irm https://github.com/madlabs-tech/onchain-data-mcp/releases/latest/download/onchain-data-mcp-installer.ps1 | iex"

Homebrew (Mac or Linux):

brew install madlabs-tech/tap/onchain-data-mcp

Claude Desktop only, no Terminal needed (Mac and Windows): download onchain-data-mcp.mcpb and double-click it. Claude Desktop asks for an optional dashboard password and optional provider keys. You can leave them all empty. Then skip to step 3.

Docker, for AI apps (Docker is a tool that runs programs in a sealed box):

docker run -i --rm -v onchain-data-mcp-data:/data ghcr.io/madlabs-tech/onchain-data-mcp:latest --config-dir /config

Docker, running in the background with the dashboard at http://127.0.0.1:8787/dashboard:

docker run -d --name onchain-data-mcp -p 127.0.0.1:8787:8787 -v onchain-data-mcp-data:/data -v onchain-data-mcp-config:/config ghcr.io/madlabs-tech/onchain-data-mcp:latest
docker exec onchain-data-mcp onchain-data-mcp password --config-dir /config

Build it yourself (needs Rust 1.90 or newer):

cargo build --release -p onchain-data-mcp
# the program is now at target/release/onchain-data-mcp

When it's done, open a new Terminal window and check it works:

onchain-data-mcp --version

The installers put the program in a folder called .cargo/bin inside your home folder (for example /Users/you/.cargo/bin/onchain-data-mcp, or C:\Users\you\.cargo\bin\onchain-data-mcp.exe on Windows).

2. Connect your AI app

Follow the steps for your app in Connect to AI apps below. Then restart the app and ask it something, like "Which chains can you read?"

3. Open the dashboard

The dashboard is a control panel in your web browser. While your AI app is open, it runs at http://127.0.0.1:8787/dashboard. It is protected by a password that was made for you. To see it, run this in the Terminal (use the same folder you used in step 2):

onchain-data-mcp password --config-dir ~/.onchain-data-mcp

You'll see something like:

Dashboard: http://127.0.0.1:8787/dashboard
Password:  f8460762fe006afc…
One-click login: http://127.0.0.1:8787/dashboard#login=f8460762fe006afc…
Config folder: /Users/you/.onchain-data-mcp
Source: /Users/you/.onchain-data-mcp/dashboard_password

Open the one-click login link and you're in. The Setup guide walks you through the rest: add keys, pick tools, connect.

If you used the Claude Desktop bundle, your folder is ~/.onchain-data-mcp unless you picked another one.

Connect to AI apps

Pick one folder for your settings and use it everywhere. We use ~/.onchain-data-mcp here (a folder called .onchain-data-mcp in your home folder). Replace you with your user name.

Why the full path? Some apps start programs from a different place, so short paths like config end up in the wrong folder. A full path always works.

Claude Desktop

1. Open Claude Desktop, go to Settings → Developer → Edit Config. This opens claude_desktop_config.json:

   • Mac: ~/Library/Application Support/Claude/claude_desktop_config.json
   • Windows: %APPDATA%\Claude\claude_desktop_config.json

2. Paste this in (keep any other servers you already have inside "mcpServers"):

   {
     "mcpServers": {
       "onchain-data": {
         "command": "/Users/you/.cargo/bin/onchain-data-mcp",
         "args": ["--config-dir", "/Users/you/.onchain-data-mcp"],
         "env": {
           "ODM__SERVER__DATA_DIR": "/Users/you/.onchain-data-mcp/data",
           "ALCHEMY_API_KEY": "",
           "HELIUS_API_KEY": ""
         }
       }
     }
   }
   

   • command is where the program is. Find yours with which onchain-data-mcp (Mac/Linux) or where onchain-data-mcp (Windows). Homebrew puts it in /opt/homebrew/bin/onchain-data-mcp.
   • On Windows, use paths like "C:\\Users\\you\\.cargo\\bin\\onchain-data-mcp.exe" (double backslashes).
   • The keys are optional. Leave them empty, remove them, or add them later in the dashboard.

3. Quit Claude Desktop completely and open it again.

Claude Code

claude mcp add onchain-data -e ODM__SERVER__DATA_DIR=$HOME/.onchain-data-mcp/data -- onchain-data-mcp --config-dir $HOME/.onchain-data-mcp

Cursor

Click the Install in Cursor button at the top, or paste this into ~/.cursor/mcp.json (or .cursor/mcp.json inside one project), then turn it on in Cursor Settings → MCP:

{
  "mcpServers": {
    "onchain-data": {
      "command": "/Users/you/.cargo/bin/onchain-data-mcp",
      "args": ["--config-dir", "/Users/you/.onchain-data-mcp"],
      "env": { "ODM__SERVER__DATA_DIR": "/Users/you/.onchain-data-mcp/data" }
    }
  }
}

VS Code

Click the Install in VS Code button at the top. To use your settings folder, open the MCP settings in VS Code and add "args": ["--config-dir", "/Users/you/.onchain-data-mcp"].

Other apps (over the web address)

If the program is already running (for example started by another app, or with onchain-data-mcp serve), any app that supports MCP over HTTP can connect to:

http://127.0.0.1:8787/mcp

The dashboard's Connect page shows ready-to-copy settings with your real paths filled in.

The dashboard

Your control panel at http://127.0.0.1:8787/dashboard. Only your own computer can open it.

Password and keys

There are three kinds of keys. Only the first one is needed, and it is made for you.

See your dashboard password at any time:

onchain-data-mcp password --config-dir ~/.onchain-data-mcp

The program also prints the dashboard address every time it starts, but never the password. It is saved in the file dashboard_password inside your settings folder.

The one-click link contains your password, so it stays in your Terminal history. That's fine on your own computer; just don't paste it into chats or screenshots.

Choose your own password: set DASHBOARD_PASSWORD to at least 12 characters, with no spaces. For Claude Desktop, add it to the "env" block, for example "DASHBOARD_PASSWORD": "my-long-secret-2026".

Make a new random password:

onchain-data-mcp password reset --config-dir ~/.onchain-data-mcp

Then restart your AI app (or the program) so it uses the new password.

Add provider keys: in the dashboard go to Providers, paste the key and click Test. Or add it to the "env" block of your AI app's settings, like "ALCHEMY_API_KEY": "your-key".

Data providers

Providers are sorted into four tiers:

Our advice: start with no keys. When you want better results, get free keys from Alchemy and Helius and paste them into the dashboard.

The full list, with limits and sign-up links, is in docs/VENDORS.md.

Available tools

These are the tools your AI app can use. You don't call them yourself; your AI assistant picks them. "Profiles" are ready-made tool sets (payments, trading, neobank, defi). By default you get all of them. You can pick a smaller set on the dashboard's Tools & Chains page.

Every tool only reads data, except tx_broadcast, which sends a transaction you already signed.

Chains and health

Wallets

Transactions

Payments

Stablecoins

Stablecoins are crypto coins meant to stay worth one dollar (or euro), like USDC and USDT.

Compliance

Money (fiat and banking)

Market and tokens

Trading

Real-world assets

Older setups can still use four legacy tools: eth_get_balance, eth_get_code, eth_gas_price and eth_get_transaction_by_hash. New setups should use the tools above.

Real-world examples

Copy any of these into your AI app.

Wallets

• "What tokens does 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 hold, on every chain?"
• "Is this address a normal wallet or a smart contract?"

Payments

• "Did transaction 0x… on Base pay at least 25 USDC to 0x…? Is it final?"
• "List new USDC deposits to my three shop addresses on Polygon since this morning."
• "Make a payment request for 10 USDC on Solana to my address."

Safety

• "Before I pay this address, check it against sanctions lists."
• "Is USDC on Arbitrum still worth one dollar?"
• "Is this new Solana token a scam?"

Money

• "What was the EUR to USD rate on 2026-03-15?"
• "Give me a statement of my wallet's transactions this month, with dollar values."
• "Why was my crypto card payment declined?"

Trading

• "Get me the best quote to swap 500 USDC to ETH on Base."
• "What was the price of SOL on 1 January 2026?"
• "How much is the network fee on Ethereum right now, in dollars?"

Tokenized stocks

• "Is this Robinhood Chain token the official NVIDIA stock token? What's its price?"

Running it for others

By default the program runs just for you, on your computer ("self-hosted").

You can also put it on a server and let other people or apps use it ("hosted"). Each customer gets their own client key, with their own limits. You manage everything from the dashboard.

The step-by-step guide is in DEPLOYMENT.md.

Troubleshooting

"missing or invalid dashboard password"

1. Run onchain-data-mcp password --config-dir <your folder> and use that password.
2. Use the same folder your AI app uses. A different folder has a different password.
3. If you changed the password, restart your AI app so it picks up the change.

"DASHBOARD_PASSWORD is too short" or "DASHBOARD_PASSWORD can only use plain letters…"

Your own password must be at least 12 characters, with no spaces or accented letters. Fix it, or remove DASHBOARD_PASSWORD to use a generated one. Until then the dashboard stays off (the rest keeps working), and you'll see "dashboard turned off" in the logs.

"The password comes from the DASHBOARD_PASSWORD setting. Change it there instead."

You set your own password, so password reset can't replace it. Change DASHBOARD_PASSWORD instead.

"HTTP not started (Address already in use); stdio only" or the dashboard page won't load

Something else is already using port 8787 (a "port" is like a door number on your computer). Often it's a second copy of this program, for example two AI apps running it at once. Your AI app still works; only the dashboard is missing. Close the other copy, or open the dashboard of the copy that is running.

The AI app doesn't show the tools, or says the server failed to start

1. Check the command path. Run which onchain-data-mcp (Mac/Linux) or where onchain-data-mcp (Windows) and paste that full path.
2. Check the settings text (JSON) has no missing commas or quotes.
3. Quit the app completely and open it again.
4. Claude Desktop logs: Mac ~/Library/Logs/Claude/, Windows %APPDATA%\Claude\logs\.

Mac says "onchain-data-mcp cannot be opened" or "developer cannot be verified"

This only happens if you downloaded the file by hand. Run this once in the folder with the file:

xattr -d com.apple.quarantine onchain-data-mcp

Linux: "GLIBC_2.35 not found"

Your Linux is older than the ready-made program supports. Use the Docker option instead.

"hosted mode requires at least one client key" or "hosted mode requires public_bind"

These only appear when running it for others. See DEPLOYMENT.md.

A tool says it's not supported on a chain

That feature needs a provider key you haven't added yet. Ask "Which chains and features can you use?" (the chain_list tool) to see what's missing, then add the key on the Providers page.

FAQ

Is it free? Yes. The program is free and open source (MIT license). It uses free data services first. Some providers have paid plans, but you never need them.

Do I need any keys? No. It works right away with the free, no-sign-up providers. Free Alchemy and Helius keys make it faster and more complete.

Which chains does it support? Ethereum, Base, Arbitrum, Optimism, Polygon, Avalanche, BNB Chain, Robinhood Chain and Solana.

Can it move my money? No. It never has your wallet's secret keys. It can prepare a transaction for you to sign in your own wallet, and tx_broadcast can send one you already signed. It can't sign anything itself.

Is my data safe? Where do my keys go? Everything stays on your computer. Your provider keys are saved in secrets.toml in your settings folder (only your user can read it on Mac and Linux) and are sent only to that provider. The dashboard only accepts connections from your own computer.

Where are my settings saved? In the folder you chose (for example ~/.onchain-data-mcp): config.toml for settings, secrets.toml for keys, dashboard_password, and a data folder with usage numbers.

How do I update it? Run the install command again (or brew upgrade onchain-data-mcp), then restart your AI app. For Claude Desktop, download and double-click the new .mcpb file.

For developers

REST API, settings reference, routing, architecture, building, testing and releases: docs/TECHNICAL.md.

Security

Found a security problem? Please report it privately, as explained in SECURITY.md.

License

MIT. The dashboard fonts are under the SIL Open Font License (OFL.txt).