> ## Documentation Index
> Fetch the complete documentation index at: https://docs.trustware.io/llms.txt
> Use this file to discover all available pages before exploring further.

# GET /allowance

> Read the ERC-20 allowance an owner has granted to a spender on a given EVM chain. Proxied through Trustware so you do not need a public RPC endpoint.

`GET https://api.trustware.io/api/v1/sdk/rpc/evm/allowance`

Returns the ERC-20 allowance an `ownerAddress` has granted to a `spenderAddress` on a specific EVM chain. Trustware proxies the underlying call so you don't have to manage public RPC endpoints or rate limits per chain.

Use this before broadcasting a route transaction whose source token is an ERC-20. If `allowance` is below `fromAmount`, prompt the user to approve the spender first.

<Note>
  The spender is the active route's provider contract (Squid, LiFi, etc.) —
  not a Trustware contract. Re-quoting can change the selected provider,
  which changes the spender; always check allowance against the `to` address
  from the latest `POST /route` response.
</Note>

## Query parameters

| Parameter        | Required | Description                                                                                                                                         |
| ---------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| `chainId`        | Yes      | EVM chain ID as a string (e.g. `"8453"` for Base, `"1"` for Ethereum).                                                                              |
| `tokenAddress`   | Yes      | ERC-20 token contract address.                                                                                                                      |
| `ownerAddress`   | Yes      | Wallet address whose allowance you are reading.                                                                                                     |
| `spenderAddress` | Yes      | The spender to check allowance against. For Trustware integrations this is `route.execution.transaction.to` from the latest `POST /route` response. |

## Request

```bash theme={null}
curl -G "https://api.trustware.io/api/v1/sdk/rpc/evm/allowance" \
  -H "X-API-Key: $TW_KEY" \
  --data-urlencode "chainId=8453" \
  --data-urlencode "tokenAddress=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913" \
  --data-urlencode "ownerAddress=0xeb212fe20f26243ec4d4df2dd49c8aa9fa75a201" \
  --data-urlencode "spenderAddress=0xce16F69375520ab01377ce7B88f5BA8C48F8D666"
```

## Response

```json theme={null}
{
  "success": true,
  "data": {
    "chainId": "8453",
    "tokenAddress": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913",
    "ownerAddress": "0xeb212fe20f26243ec4d4df2dd49c8aa9fa75a201",
    "spenderAddress": "0xce16f69375520ab01377ce7b88f5ba8c48f8d666",
    "allowance": "115792089237316195423570985008687907853269984665640564039457584007913129639935",
    "rpcHost": "base-mainnet.example"
  }
}
```

| Field                 | Description                                                                                                                    |
| --------------------- | ------------------------------------------------------------------------------------------------------------------------------ |
| `success`             | `true` if the call resolved against the chain.                                                                                 |
| `data.chainId`        | Chain ID the call was made against.                                                                                            |
| `data.tokenAddress`   | Lowercased token contract address.                                                                                             |
| `data.ownerAddress`   | Lowercased owner address.                                                                                                      |
| `data.spenderAddress` | Lowercased spender address.                                                                                                    |
| `data.allowance`      | Allowance as a string-encoded `uint256` in the token's smallest unit. The value `2^256 - 1` indicates an "unlimited" approval. |
| `data.rpcHost`        | The upstream RPC host Trustware used. Useful for debugging.                                                                    |

## Errors

The endpoint returns `{ "success": false, "error": "...", ... }` for validation failures (invalid address, unsupported chain) or upstream RPC failures. Inspect the HTTP status code alongside the error payload:

* `400` — Malformed address, unsupported chain, or missing query parameter.
* `429` — Rate limit hit; honor the `Retry-After` header.
* `500` / `502` — Upstream RPC failed after retries.

<Note>
  Compare `allowance` to your route's `fromAmount` (both in the token's
  smallest unit). If `allowance < fromAmount`, prompt the user to approve the
  spender before broadcasting.
</Note>