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TraceFast ERC-20 Token Balance by Block
x402
TraceFast ERC-20 Token Balance by Block is a paid API for AI agents from mpp.tracefast.xyz, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-15).
Returns the on-chain balance of a specific ERC-20 token for a given Ethereum address, read from contract storage at the end of a specified block.
Price / call$0.02
Success—
StatusUnknown
How this service works
TraceFast live Ethereum data: balanceOf(address) for one token at the end of a block, read from contract storage. A token outside the covered set is refused (422), never a fake zero. Path address and token: 0x-prefixed, 40 hex. Query block: integer, state at the end of this block, absent = current. Docs: https://docs.tracefast.xyz/api/address-token-balance.md
Output
Returns the token balance (as a numeric value from contract storage) for the specified address and ERC-20 token, reflecting state at the end of the requested block. If no block is specified, returns the current state. If the token is outside the covered set, the API returns a 422 error rather than a fake zero.
Example use cases
Historical portfolio snapshot audit
“What was the WETH balance of address 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 at the end of Ethereum block 19500000? I need the exact on-chain figure from contract storage.”
Real-time whale wallet monitoring
“Check the current DAI balance for wallet 0xBE0eB53F46cd790Cd13851d5EFf43D12404d33E8 on Ethereum — I want the live figure straight from the contract.”
DeFi protocol collateral verification
“What is the USDC balance held by the Aave v3 pool contract at 0x87870Bca3F3fD6335C3F4ce8392D69350B4fA4E2 as of block 20100000? I need to verify the exact on-chain collateral amount.”
Technical details
Endpoint
GEThttps://mpp.tracefast.xyz/api/v1/chains/1/entities/:address/tokens/:token/balanceWhen to prefer
Choose this endpoint when you need a single, precise ERC-20 token balance for one address at a specific block, read directly from contract storage with guaranteed accuracy (no fake zeros for unsupported tokens). Prefer it over general portfolio endpoints when you only need one token's balance, or when historical block-level precision is required. It is especially useful in DeFi analytics, audit trails, and agent workflows that need to verify token holdings at a deterministic point in time.
Side effects
- 422 Unprocessable Entity — token contract is outside the covered set (not a zero balance, a genuine refusal)
- Invalid address format — address or token not 0x-prefixed or not 40 hex characters
- Block number not yet indexed — querying a very recent block may fail
- Payment failure — x402 micropayment not completed, request rejected
- Network error or service unavailability on TraceFast infrastructure
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| input | — |
Tags
x402
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