> ## Documentation Index > Fetch the complete documentation index at: https://docs.houdiniswap.com/llms.txt > Use this file to discover all available pages before exploring further. # Private Routes with an On-chain Hop > Reach more tokens privately. Collect a second refund address before you turn it on. ## Overview Some tokens have no direct private route. For these tokens we can still offer a private swap: the swap runs privately to a hub token (for example USDC), then an on-chain hop takes the hub token to the token your user wants. > [!NOTE] > > **Coverage**: With this feature, almost any token on Solana and on high-volume EVM chains, such as Ethereum, Base, Robinhood, Arbitrum, BNB Chain, Polygon, Optimism, Avalanche and more, can be the output of a private swap. ### How the route works The on-chain hop is an **extra leg added after a normal private swap**. The private part is unchanged: ```mermaid theme={null} graph LR A[User Deposit] --> B[Private swap] B --> C[Hub token, e.g. USDC] C --> D[On-chain hop] D --> E[Destination Wallet] style A fill:#e1f5ff,color:#000 style E fill:#e1f5ff,color:#000 style B fill:#fff3cd,color:#000 style C fill:#fff3cd,color:#000 style D fill:#d4edda,color:#000 ``` 1. **Private leg**: the deposit goes through the same multi-hop private routing as any [private swap](/developer-hub/swap-flows/private-swap.md), and comes out as the hub token. This is what breaks the link between your user's deposit and the output. 2. **On-chain hop**: the hub token is swapped on-chain into the destination token and sent to `addressTo`. The swap stays private. The on-chain hop starts only after the private leg has finished, so the user's deposit is never linked to it. This route needs one extra field when you create the exchange: `intermediateRefundAddress`. > [!WARNING] > > **Add support for `intermediateRefundAddress` before you turn the feature on.** If you turn it on first, your users will get quotes that you cannot turn into orders. ## How it fits in This is an **option on the [Private Swap](/developer-hub/swap-flows/private-swap.md) flow**, not a separate flow. Fetching tokens, sending the deposit and polling status are unchanged. Only these things differ: | Stage | What changes | | - | - | | Partner settings | The feature must be turned on for your account. See [Turn it on](#turn-it-on) | | `GET /quotes` | Some private quotes now reach tokens with no direct private route. They carry three extra fields. See [Spot the route in a quote](#spot-the-route-in-a-quote) | | `POST /exchanges` | Send `intermediateRefundAddress` for those quotes | ## When you get this route All of these must be true: * The feature is turned on for your account. * The quote is private (`types=private`). * The quote is floating rate, not [fixed](/developer-hub/swap-flows/fixed-rate-swap.md). * The amount is the send amount (`amountType=send`), not the receive amount. * No direct private route exists to the destination token. When a token has a direct route, you get the normal private quote, as before. ## Turn it on To turn on **Private routes with on-chain hop** for your account, contact your Houdini representative and we will turn it on for you. To check the setting, call [Get partner profile](/api-reference/partner-account/get-partner-profile.md) (`GET /me`) and read `privateOnchainLegEnabled`. ## Limits This route has its own amount limits, and they are lower than for a normal private swap. When the destination token can only be reached through this route, an amount outside the limits returns an error instead of an empty `quotes` array: * `422 QUOTE_OVER_LIMIT` when the amount is too high * `422 AMOUNT_TOO_LOW` when the amount is too low The error message gives the allowed range. The same limits are checked again when you create the exchange. ## Spot the route in a quote A quote for this route has these extra fields: | Field | Type | Meaning | | - | - | - | | `requiresIntermediateRefundAddress` | boolean | `true`. You must send `intermediateRefundAddress` when you create the exchange | | `intermediateRefundChain` | string | Chain the address must be on, for example `base`, `ethereum` or `solana` | | `intermediateRefundToken` | string | Token the address would get back, for example `USDC` | Check `requiresIntermediateRefundAddress` on every private quote. When it is `true`, ask your user for a wallet on `intermediateRefundChain` before they confirm the swap. ## Create the exchange Send the quote's `quoteId` as usual, plus `intermediateRefundAddress`: ```json theme={null} { "quoteId": "6689b73ec90e45f3b3e51566", "addressTo": "", "refundAddress": "", "intermediateRefundAddress": "0x1111111111111111111111111111111111111111" } ``` Rules for `intermediateRefundAddress`: * It must be a valid address on `intermediateRefundChain`. * It must be able to receive `intermediateRefundToken`. * **Use a wallet your user controls, not an exchange deposit address.** ### Two refund addresses | Field | Covers | Chain | | - | - | - | | `refundAddress` | The deposit leg | Source chain | | `intermediateRefundAddress` | The on-chain hop. If the hop cannot finish, the hub token is sent here | `intermediateRefundChain` | ## Error Codes | Code | HTTP | Why | What to do | | - | - | - | - | | `INTERMEDIATE_REFUND_ADDRESS_REQUIRED` | 422 | The quote needs `intermediateRefundAddress` and you did not send it | Collect the address and send it with the exchange | | `ADDRESS_REFUND_INVALID_FOR_CHAIN` | 422 | `intermediateRefundAddress` is not a valid address for `intermediateRefundChain` | Validate the address against `intermediateRefundChain`, not the source chain | | `ONCHAIN_LEG_ROUTE_NOT_AVAILABLE` | 422 | The route is no longer available, for example because the feature was turned off after you got the quote | Get a new quote | | `VALIDATION_ERROR` | 422 | The quote has expired. `fields.quoteId` says so | Get a new quote | | `QUOTE_OVER_LIMIT` / `AMOUNT_TOO_LOW` | 422 | The amount is outside this route's limits | See [Limits](#limits) | > [!NOTE] > > These errors are not retried on another route. Fix the request or get a new quote. *** ## Next Steps > **[Private Swap](/developer-hub/swap-flows/private-swap.md)** > > The base private swap flow > **[Order Lifecycle](/developer-hub/core-concepts/order-lifecycle.md)** > > Understand all order statuses > **[Error Codes](/developer-hub/troubleshooting/error-codes-and-troubleshooting.md)** > > Full list of API errors > **[Fixed Rate & Reverse Quote](/developer-hub/swap-flows/fixed-rate-swap.md)** > > Lock the rate or set the receive amount This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.