Knit API Documentation
Step 3: Permit2 Approval (One-Time)
{{baseUrl}}/api/v1/managed-signing/requestsThis is a one-time on-chain transaction that approves the Permit2 contract to spend USDC on behalf of your wallet. After this approval, all subsequent CPN V2 payments use gasless EIP-712 signatures.
Prerequisites
- Wallet must have MATIC (or native token) for gas fees
- USDC token address for your network
- Permit2 contract address for your network
Headers
X-API-KEY: Your API key for authentication.Accept: Set toapplication/jsonto receive responses in JSON format.Content-Type: Set toapplication/json.
Request Body
{
"walletId": "<local-wallet-id>",
"network": "MATIC_MAINNET",
"type": "evm_tx",
"kind": "erc20_approve",
"payload": {
"token": "<USDC token address>",
"spender": "<Permit2 contract address>",
"amount": "<approval amount>"
},
"broadcast": true
}| Field | Type | Description |
|---|---|---|
walletId | string | Your local wallet ID from Step 1 |
network | string | Target network (e.g., MATIC_MAINNET) |
type | string | Must be evm_tx for on-chain transaction |
kind | string | Must be erc20_approve |
payload.token | string | USDC contract address |
payload.spender | string | Permit2 contract address |
payload.amount | string | Approval amount (use max for unlimited) |
broadcast | boolean | Set to true to broadcast on-chain |
Approval Amount
- For unlimited approval: use a large number like
115792089237316195423570985008687907853269984665640564039457584007913129639935(max uint256) - For limited approval: specify the exact amount in token units
Sample Request
curl --location -g '{{baseUrl}}/api/v1/managed-signing/requests' \
--header 'X-API-KEY: {{apiKey}}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"walletId": "<local-wallet-id>",
"network": "MATIC_MAINNET",
"type": "evm_tx",
"kind": "erc20_approve",
"payload": {
"token": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
"spender": "0x000000000022D473030F116dDEE9F6B43aC78BA3",
"amount": "115792089237316195423570985008687907853269984665640564039457584007913129639935"
},
"broadcast": true
}'Sample Response
Sample Response
{
"statusCode": 201,
"message": "Signing request created",
"data": {
"id": "<local-request-id>",
"businessId": "<business-id>",
"walletId": "<local-wallet-id>",
"network": "MATIC_MAINNET",
"type": "evm_tx",
"kind": "erc20_approve",
"status": "SIGNED",
"payload": {
"token": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
"spender": "0x000000000022D473030F116dDEE9F6B43aC78BA3",
"amount": "115792089237316195423570985008687907853269984665640564039457584007913129639935"
},
"txHash": "0x...",
"broadcast": true,
"createdAt": "2026-01-20T18:30:40.912Z",
"updatedAt": "2026-01-20T18:30:40.912Z"
},
"success": true
}Important Notes
- This transaction requires gas paid by the wallet
- The service will auto-fill gas/fees/nonce if an RPC is configured for the network
- If
broadcastisfalse, you'll receive the signed transaction to broadcast yourself - This approval only needs to be done once per token
Next Step
Proceed to Per-Payment Signature to sign individual payments.
