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Coin Railz Token Approval Transaction Generator
x402
Coin Railz Token Approval Transaction Generator is a paid API for AI agents from coinrailz.com, paid per call via x402, $0.2/call, status unknown (last checked 2026-09-13).
Generates ERC-20 token approval transactions for DeFi agents to authorize a spender (e.g. DEX router) to spend a specified amount of a given token on a blockchain network
Price / call$0.2
Success—
StatusUnknown
How this service works
Token approval transaction generator - required infrastructure for DeFi agents (B2B2C infrastructure)
Output
Returns an approvalTransaction object containing the full transaction data (to, data, value, etc.) needed to submit an ERC-20 approve() call on-chain, authorizing the specified spender to transfer up to the given amount of the token.
Example use cases
Example prompt
“Generate a token approval transaction on Ethereum to let the Uniswap v3 router (0xE592427A0AEce92De3Edee1F18E0157C05861564) spend up to 500 USDC (token address 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48) on my behalf.”
Technical details
Endpoint
POSThttps://coinrailz.com/x402/service/approval-managerWhen to prefer
Use this endpoint when an AI agent needs to programmatically construct an ERC-20 token approval (allowance) transaction before executing a DeFi swap or interaction that requires a prior approve() call. Prefer this over manually encoding approve() calldata when you need a ready-to-broadcast transaction object for a specific chain and spender without managing ABI encoding yourself.
Side effects
- Invalid or unrecognized chain identifier — returns error indicating unsupported network
- Malformed token address or spender address — returns validation error
- Amount value not parseable (must be numeric string or 'unlimited') — returns parsing error
- Payment failure (insufficient USDC for $0.2 fee) — returns 402 Payment Required
- Missing required fields (chain, amount, spender, tokenAddress) — returns 400 Bad Request
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| chainrequired | string | Blockchain network |
| amountrequired | string | Amount to approve or 'unlimited' |
| spenderrequired | string | Spender address (DEX router) |
| tokenAddressrequired | string | Token to approve |
Output
Schema · Response
| Field | Type | Description |
|---|---|---|
| approvalTransaction | object | Approval transaction data |
Tags
x402
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