# Cross-chain swap (bridge aggregation)

Endpoint reference for the 1delta API. Index: https://docs.1delta.io/llms.txt · every endpoint: https://docs.1delta.io/llms-full.txt

---

### GET /v1/actions/swap/x-chain

- operationId: `cross-chain-swap-bridge-aggregation`
- docs: https://docs.1delta.io/1delta-api/cross-chain-swap-bridge-aggregation/
- markdown: https://docs.1delta.io/1delta-api/cross-chain-swap-bridge-aggregation.md
- tags: Swap

Cross-chain swap (bridge aggregation)

Quote a cross-chain swap across all supported bridge aggregators (Across, LI.FI, Squid, Stargate, Symbiosis, XY Finance, DZap, …) and build the winning transactions. Omit `account` for quote-only. Include `account` to build full transaction calldata. Each build quote carries `approvalTarget`/`approvalRequired`, and `actions.permissions` holds one ERC-20 approve per unique spender (composed routes share the 1delta composer; plain bridges use their own deposit contract) with a `spender` field — execute only the permission whose `spender` equals your chosen quote's `approvalTarget`. When `fromChainId` equals `toChainId` the request falls back to the spot meta-aggregator (same response shape with `aggregator` instead of `bridge` per quote, marked `fallback: 'spot'`).

**Parameters**

| Name | In | Type | Required | Description |
| --- | --- | --- | --- | --- |
| `fromChainId` | query | string | yes | Source chain ID |
| `toChainId` | query | string | yes | Destination chain ID |
| `tokenIn` | query | string | yes | Input token address on the source chain (zero address for native) |
| `tokenOut` | query | string | yes | Output token address on the destination chain (zero address for native) |
| `amount` | query | string | yes | Input amount in wei |
| `slippage` | query | number | yes | Slippage tolerance (basis points) |
| `account` | query | string | no | Account address on the source chain. Include to build transactions, omit for quote-only. |
| `receiver` | query | string | no | Receiver address on the destination chain (defaults to account) |
| `order` | query | "CHEAPEST" \| "FASTEST" | no | Route preference |
| `bridges` | query | string | no | Comma-separated bridge filter (e.g. `Across,LI.FI`). Defaults to all supported bridges. |

**Response `200`** — Cross-chain swap quote or full build

| Field | Type | Description |
| --- | --- | --- |
| `success` | true |  |
| `data` | object | Informational data (quotes, simulation results, etc.) |
| `data.currencyIn` | object | Input currency info (source chain) |
| `data.currencyOut` | object | Output currency info (destination chain) |
| `data.quotes` | object[] | Candidate routes, best output first. Execute exactly one. |
| `data.quotes[].bridge` | string |  |
| `data.quotes[].tradeInput` | number |  |
| `data.quotes[].tradeOutput` | number |  |
| `data.quotes[].estimatedDuration` | number | Estimated bridging duration in seconds |
| `data.quotes[].approvalTarget` | string | This bridge's deposit contract — the ERC-20 approve spender |
| `data.quotes[].approvalRequired` | boolean | False when the existing on-chain allowance already covers the input amount |
| `data.quotes[].tx` | object | An EVM transaction ready to sign and broadcast. Send `to`, `data` and `value` as-is; do not re-encode them. |
| `data.quotes[].tx.to` | string | Target contract address |
| `data.quotes[].tx.data` | string | Encoded calldata |
| `data.quotes[].tx.value` | string | ETH value to send with the transaction |
| `data.quotes[].tx.description` | string | Human-readable label. For `alternatives`, this is the aggregator name (e.g. "Paraswap"). For `transactions`, describes the setup action (e.g. "Switch e-mode to 1"). |
| `data.permissionTxns` | object[] | ERC-20 approves per bridge deposit contract; each is labeled with the bridge name — execute only the one matching the chosen quote |
| `data.permissionTxns[].to` | string | Target contract address |
| `data.permissionTxns[].data` | string | Encoded calldata |
| `data.permissionTxns[].value` | string | ETH value |
| `data.permissionTxns[].description` | string | Human-readable description of the approval (e.g. "Approve borrow for AAVE_V3", "Approve ERC20") |
| `data.permissionTxns[].spender` | string | ERC-20 approve spender (x-chain permissions). Match it against the selected quote's `approvalTarget` — several bridges can share one spender, so do not match by description. |
| `data.quotes[].aggregator` | string |  |
| `actions` | object | Transaction calldata and approvals. Null for quote-only responses (no account provided). |
| `actions.transactions` | object[] | Pre-trade setup transactions (e.g. e-mode switch, collateral enable). Execute these before the main swap. Empty when no setup is needed. |
| `actions.transactions[].to` | string | Target contract address |
| `actions.transactions[].data` | string | Encoded calldata |
| `actions.transactions[].value` | string | ETH value to send with the transaction |
| `actions.transactions[].description` | string | Human-readable label. For `alternatives`, this is the aggregator name (e.g. "Paraswap"). For `transactions`, describes the setup action (e.g. "Switch e-mode to 1"). |
| `actions.alternatives` | object[] | DEX aggregator swap transactions sorted by best output (descending). Each entry's `description` is the aggregator name. The client should pick one to execute. Present on loop action endpoints. |
| `actions.alternatives[].to` | string | Target contract address |
| `actions.alternatives[].data` | string | Encoded calldata |
| `actions.alternatives[].value` | string | ETH value to send with the transaction |
| `actions.alternatives[].description` | string | Human-readable label. For `alternatives`, this is the aggregator name (e.g. "Paraswap"). For `transactions`, describes the setup action (e.g. "Switch e-mode to 1"). |
| `actions.permissions` | object[] | Approval/delegation transactions that must execute before both `transactions` and `alternatives`. Includes ERC20 allowances (targeting the composer contract) and lender borrow/withdrawal delegations (targeting the lending protocol contract directly). Filtered against on-chain state so only missing approvals are returned. Null when no approvals are needed. |
| `actions.permissions[].to` | string | Target contract address |
| `actions.permissions[].data` | string | Encoded calldata |
| `actions.permissions[].value` | string | ETH value |
| `actions.permissions[].description` | string | Human-readable description of the approval (e.g. "Approve borrow for AAVE_V3", "Approve ERC20") |
| `actions.permissions[].spender` | string | ERC-20 approve spender (x-chain permissions). Match it against the selected quote's `approvalTarget` — several bridges can share one spender, so do not match by description. |

**Example response**

```json
{
  "success": true,
  "data": {
    "currencyIn": {},
    "currencyOut": {},
    "quotes": [
      {
        "bridge": "string",
        "tradeInput": 1,
        "tradeOutput": 1,
        "estimatedDuration": 1
      }
    ]
  },
  "actions": {
    "transactions": [
      {
        "to": "0x87870Bca3F3fD6335C3F4ce8392D69350B4fA4E2",
        "data": "0x617ba037000000000000000000000000c02aaa39b2",
        "value": "0",
        "description": "string"
      }
    ],
    "alternatives": [
      {
        "to": "0x87870Bca3F3fD6335C3F4ce8392D69350B4fA4E2",
        "data": "0x617ba037000000000000000000000000c02aaa39b2",
        "value": "0",
        "description": "string"
      }
    ],
    "permissions": [
      {
        "to": "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
        "data": "0x617ba037000000000000000000000000c02aaa39b2",
        "value": "0",
        "description": "string",
        "spender": "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2"
      }
    ]
  }
}
```

**Response `400`** — Validation error

**Response `429`** — Rate limited. Unauthenticated callers share a per-IP budget; send an `x-api-key` header to lift it. Retry with exponential backoff.

**Response `500`** — Unexpected server error. Safe to retry with backoff.

**Response `502`** — An upstream data source or protocol origin failed (`error.code` is `ORIGIN_FAILED`). `error.details` carries the per-origin status. This is also what a missing or malformed required parameter currently returns, rather than a 400.