Tools / Crypto & Base
ERC-20 Allowance $0.001 / call
Check a spending allowance; flags unlimited.
GET /v1/base/allowanceReturns how much of a token an owner has approved a spender to move on Base, and explicitly flags unlimited approvals — a common security concern.
Parameters
owner required | Token owner address |
spender required | Approved spender address |
token | 'usdc' (default) or a contract address |
Example
macOS / Linuxcurl -s "https://quartermaster.surewhynot.app/v1/base/allowance?owner=0xc2a36e22ecbf353086cf83e7beea78bc28a64083&spender=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"curl.exe -s "https://quartermaster.surewhynot.app/v1/base/allowance?owner=0xc2a36e22ecbf353086cf83e7beea78bc28a64083&spender=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"Unpaid, these return 402 Payment Required with the payment details in the header (add -i to see them). curl.exe ships with Windows 10+ and works in cmd and both PowerShell versions. To actually pay, use an x402 client (see Connect) or call it as the MCP tool. Cost: $0.001 per call.
FAQ
Why does unlimited matter?
An unlimited approval lets a spender move all of your tokens, forever, until revoked — worth knowing before you trust a contract.
How do I pay for this endpoint?
Call it with no payment and you receive HTTP 402 with machine-readable payment requirements. Attach a USDC payment on Base with any x402 client (for example @x402/fetch) and retry — the whole loop is two requests. This call costs $0.001 in USDC.
Do I need an account or API key?
No. There are no accounts, logins, or API keys anywhere in Quartermaster. Payment is per call over the x402 protocol; your wallet is your identity.
Can I call this as an MCP tool instead?
Yes. Quartermaster is also an MCP server at /mcp, so any MCP client (Claude Code, Claude.ai, Cursor) can mount this tool. See /connect for setup.