# Pair Configuration

The pair configuration endpoint checks whether a trading pair is supported and returns token metadata including decimal precision. Use it to validate tokens and amounts before calling the quote endpoint.

## Endpoint

```
GET /api/v1/pair-config
```

## Request Parameters

| Parameter | Type   | Required | Description                                   |
| --------- | ------ | -------- | --------------------------------------------- |
| `from`    | string | Yes      | Input token identifier (e.g., `WEGLD-bd4d79`) |
| `to`      | string | Yes      | Output token identifier (e.g., `USDC-c76f1f`) |

## Response Format

### Supported Pair

```json
{
  "from": "WEGLD-bd4d79",
  "to": "USDC-c76f1f",
  "supported": true,
  "decimalsIn": 18,
  "decimalsOut": 6,
  "minAmountIn": "1000000000",
  "minAmountInShort": 0.000000001
}
```

### Unsupported Pair — Unknown Token

```json
{
  "from": "WEGLD-bd4d79",
  "to": "UNKNOWN-123456",
  "supported": false,
  "error": "unknown tokenOut"
}
```

### Unsupported Pair — No Route

```json
{
  "from": "TOKEN-a1b2c3",
  "to": "TOKEN-d4e5f6",
  "supported": false,
  "error": "no path between tokens"
}
```

## Response Fields

| Field              | Type    | Description                                                                    |
| ------------------ | ------- | ------------------------------------------------------------------------------ |
| `from`             | string  | Input token identifier                                                         |
| `to`               | string  | Output token identifier                                                        |
| `supported`        | boolean | `true` if the pair can be traded; `false` otherwise                            |
| `decimalsIn`       | number  | Decimal precision of the input token. Present when `supported: true`.          |
| `decimalsOut`      | number  | Decimal precision of the output token. Present when `supported: true`.         |
| `minAmountIn`      | string  | Minimum viable input amount in smallest units. Present when `supported: true`. |
| `minAmountInShort` | number  | Human-readable minimum input amount. Present when `supported: true`.           |
| `error`            | string  | Error description. Present when `supported: false`.                            |

## Validate Before Quote

{% hint style="info" %}
Call `pair-config` before requesting a quote to catch invalid tokens and provide accurate error messages to your users. It is a lightweight check that does not run the full routing algorithm.
{% endhint %}

```bash
curl "https://swap.xoxno.com/api/v1/pair-config?\
from=WEGLD-bd4d79&\
to=USDC-c76f1f"
```

```javascript
async function checkPairSupport(tokenIn, tokenOut) {
  const response = await fetch(
    `https://swap.xoxno.com/api/v1/pair-config?from=${tokenIn}&to=${tokenOut}`
  );
  const config = await response.json();

  if (!config.supported) {
    throw new Error(`Pair not supported: ${config.error}`);
  }

  return {
    decimalsIn: config.decimalsIn,
    decimalsOut: config.decimalsOut,
    minAmountIn: BigInt(config.minAmountIn)
  };
}
```

### Validate Amount Before Quoting

```javascript
async function getQuoteWithValidation(from, to, amount) {
  const config = await checkPairSupport(from, to);

  if (BigInt(amount) < BigInt(config.minAmountIn)) {
    throw new Error(
      `Amount ${amount} is below the minimum of ${config.minAmountInShort} ${from}`
    );
  }

  return fetchQuote({ from, to, amountIn: amount });
}
```

### Build a Token Selector

Use `pair-config` to determine which output tokens are available for a given input token:

```javascript
async function getAvailableOutputTokens(inputToken, allTokens) {
  const results = await Promise.all(
    allTokens
      .filter(token => token !== inputToken)
      .map(async token => {
        const config = await checkPairSupport(inputToken, token);
        return config.supported ? { token, decimals: config.decimalsOut } : null;
      })
  );

  return results.filter(Boolean);
}
```

## Token Decimals Reference

Common token decimal values on MultiversX:

| Token        | Decimals | Smallest unit example           |
| ------------ | -------- | ------------------------------- |
| EGLD / WEGLD | 18       | `1000000000000000000` = 1 WEGLD |
| USDC         | 6        | `1000000` = 1 USDC              |
| USDT         | 6        | `1000000` = 1 USDT              |
| UTK          | 18       | `1000000000000000000` = 1 UTK   |
| MEX          | 18       | `1000000000000000000` = 1 MEX   |

{% hint style="warning" %}
Always use the `decimalsIn` / `decimalsOut` values from the API response rather than hardcoded constants. Some tokens have non-standard decimal configurations.
{% endhint %}

## Related Topics

* [Quote Endpoint](https://docs.xoxno.com/developers/aggregator-api/quote) — Full quote API reference
* [Integration Guide](https://docs.xoxno.com/developers/aggregator-api/integration-guide) — Step-by-step integration walkthrough
* [Error Reference](https://github.com/XOXNO/docs/blob/main/developers/aggregator-api/error-reference.md) — Full error code reference