Wallet Portfolio Tracker API

Full crypto wallet holdings across chains -- ETH, ERC-20 tokens, USD values. Portfolio tracking for agents. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.

Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.

Quickstart -- MCP

Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):

{
  "mcpServers": {
    "wallet-portfolio": {
      "url": "https://wallet-portfolio.api.klymax402.com/mcp"
    }
  }
}

Quickstart -- HTTP (x402)

curl "https://wallet-portfolio.api.klymax402.com/api/portfolio?address=0x0000000000000000000000000000000000dEaD"
# -> 402 Payment Required, with an x402 payment challenge in the response body

Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.

Tools

Tool	Method	Path	Price	Description
`wallet_get_portfolio`	GET	`/api/portfolio`	$0.008	Get full portfolio with all token balances and USD values
`wallet_get_portfolio`	POST	`/api/portfolio`	$0.008	Get full portfolio with all token balances and USD values (POST variant)
`wallet_get_balance`	GET	`/api/balance`	$0.003	Get ETH and USDC balance only
`wallet_get_balance`	POST	`/api/balance`	$0.003	Get ETH and USDC balance only (POST variant)

`wallet_get_portfolio`

Use this when you need to check a crypto wallet's holdings across chains. Returns a full portfolio breakdown in JSON.

Parameters

Name	Type	Required	Description
`address`	string	yes	Wallet address (0x...)
`chain`	string	no	Blockchain network (default: base)

Returns

nativeBalance -- ETH balance with USD value
tokens -- array of ERC-20 tokens with symbol, balance, USD value, contract address
totalValueUsd -- aggregate portfolio value in USD
chain -- which network was queried

Example response:

{"nativeBalance":{"symbol":"ETH","balance":"1.234","valueUsd":3827.50},"tokens":[{"symbol":"USDC","balance":"500.00","valueUsd":500.00}],"totalValueUsd":4327.50,"chain":"base"}

When to use: executing a swap to verify the wallet has sufficient balance. Essential for portfolio tracking, balance checks, and agent self-reporting.

Not for: gas prices (use gas_get_current_price), swap quotes (use dex_get_swap_quote), yield opportunities (use defi_find_best_yields).

`wallet_get_portfolio`

Use this when you need to check a crypto wallet's holdings across chains. Returns a full portfolio breakdown in JSON.

Parameters

Name	Type	Required	Description
`address`	string	yes	Wallet address (0x...)
`chain`	string	no	Blockchain network (default: base)

Returns

nativeBalance -- ETH balance with USD value
tokens -- array of ERC-20 tokens with symbol, balance, USD value, contract address
totalValueUsd -- aggregate portfolio value in USD
chain -- which network was queried

Example response:

{"nativeBalance":{"symbol":"ETH","balance":"1.234","valueUsd":3827.50},"tokens":[{"symbol":"USDC","balance":"500.00","valueUsd":500.00}],"totalValueUsd":4327.50,"chain":"base"}

When to use: executing a swap to verify the wallet has sufficient balance. Essential for portfolio tracking, balance checks, and agent self-reporting.

Not for: gas prices (use gas_get_current_price), swap quotes (use dex_get_swap_quote), yield opportunities (use defi_find_best_yields).

`wallet_get_balance`

Use this when you need a quick check of a wallet's ETH and USDC balance only. Returns a lightweight JSON response -- cheaper than full portfolio.

Parameters

Name	Type	Required	Description
`address`	string	yes	Wallet address (0x...)
`chain`	string	no	Blockchain network (default: base)

Returns

ethBalance -- native ETH balance with USD value
usdcBalance -- USDC balance with USD value
chain -- which network was queried

Example response:

{"ethBalance":{"balance":"2.5","valueUsd":7750.00},"usdcBalance":{"balance":"1000.00","valueUsd":1000.00},"chain":"base"}

When to use: quick pre-trade balance verification when you only care about ETH and USDC. Faster and cheaper than wallet_get_portfolio.

Not for: full portfolio with all tokens (use wallet_get_portfolio), gas prices (use gas_get_current_price).

`wallet_get_balance`

Use this when you need a quick check of a wallet's ETH and USDC balance only. Returns a lightweight JSON response -- cheaper than full portfolio.

Parameters

Name	Type	Required	Description
`address`	string	yes	Wallet address (0x...)
`chain`	string	no	Blockchain network (default: base)

Returns

ethBalance -- native ETH balance with USD value
usdcBalance -- USDC balance with USD value
chain -- which network was queried

Example response:

{"ethBalance":{"balance":"2.5","valueUsd":7750.00},"usdcBalance":{"balance":"1000.00","valueUsd":1000.00},"chain":"base"}

When to use: quick pre-trade balance verification when you only care about ETH and USDC. Faster and cheaper than wallet_get_portfolio.

Not for: full portfolio with all tokens (use wallet_get_portfolio), gas prices (use gas_get_current_price).

Example agent prompts

"Check a crypto wallet's holdings across chains"
"Check a crypto wallet's holdings across chains"
"A quick check of a wallet's ETH and USDC balance only"

Payment

Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
Network: Base L2 (eip155:8453)
Asset: USDC
Facilitator: Coinbase CDP (primary), PayAI (fallback)
Also reachable via ATXP (OAuth-wrapped x402, RFC 9728 protected-resource metadata)

Part of klymax402

100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.

Catalog: https://klymax402.com/llms.txt
Full API reference: https://klymax402.com/llms-full.txt
Live stats: https://klymax402.com/stats

License

MIT