> ## 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. # Get token approval data > Returns what the wallet must approve before a DEX swap. Call this first — both arrays come back empty when the allowance already covers the swap. - `approvals` — transactions to send. After sending them, poll [Check token allowance](/api-reference/on-chain-dex-or-bridge/check-token-allowance) until it returns true. - `signatures` — EIP-712 permits to sign instead, when the token and provider both support EIP-2612 ## OpenAPI ````yaml https://api-partner.houdiniswap.com/v2/openapi.json post /dex/approve openapi: 3.0.0 info: title: Houdini Swap Partner API version: 2.1.2 description: >- Quote and execute private, standard, and DEX swaps — one at a time or batched. license: name: ISC contact: {} servers: - url: https://api-partner.houdiniswap.com/v2 security: [] tags: - name: Private and Standard Swaps description: >- CEX swaps in two modes, sharing the same endpoints — pick one with the `types` parameter. - `types=standard` — direct single-leg swap. Fastest, no privacy hop. - `types=private` — two legs through a privacy bridge, so deposit and payout are not linkable on-chain. Adds `anonymous`, `useXmr`, `rotatePayoutWallets` and the `inLeg*` / `outLeg*` filters. Flow: [Get tokens](/api-reference/private-and-standard-swaps/get-tokens) with `hasCex=true` → [Get quotes](/api-reference/private-and-standard-swaps/get-quotes) → [Create exchange](/api-reference/private-and-standard-swaps/create-exchange) → [track the order](/api-reference/private-and-standard-swaps/get-order-details). `markup` works in both modes. - name: Private Send description: >- Send a token to another wallet privately — same token in and out, with no on-chain link between the two addresses. - find eligible tokens with [Get tokens](/api-reference/private-send/get-tokens) and `hasSelfPrivate=true` - quote with Get private send quote, then create with Create private send order - you can also stay on the main endpoints with a private same-token `quoteId` See the [Private send](/docs/v2/private-send) guide. - name: Multi-Exchange description: >- Create and track a group of swaps sharing one `multiId`. - post the orders straight to Create multi exchange — there is no quote step and no `quoteId` - Get multi quotes is optional, for showing rates first - each order gets its own deposit address; poll [Get batch status](/api-reference/multi-exchange/get-batch-status) for every leg - CEX standard and private only — no DEX in a batch To fund the whole group in one transaction, see Bundler SOL or Bundler EVM. See the [multi-swap flow](https://docs.houdiniswap.com/developer-hub/swap-flows/multi-swap) for the full sequence. - name: Bundler SOL description: >- Fund a whole multi-exchange group with one Solana batch transfer. - one call — Get batch transaction returns the transaction to sign and broadcast - up to 10 deposits per batch; every order must send the same token - find batchable tokens with [Get tokens](/api-reference/multi-exchange/get-tokens) and `hasBundler=true` - nothing to submit back afterwards — retry and recovery are EVM-only See the [multi-swap flow](https://docs.houdiniswap.com/developer-hub/swap-flows/multi-swap) for the full sequence. - name: Bundler EVM description: >- Fund a whole multi-exchange group with one ERC-4337 UserOperation, submitted through the bundler. - Ethereum, Base and BNB Smart Chain only; other EVM chains are rejected - up to 20 legs per batch; every order must send the same source token - find batchable tokens with [Get tokens](/api-reference/multi-exchange/get-tokens) and `hasBundler=true` - build the UserOp, then submit the signed result - if a bundle fails: retry within 30 minutes, or recover stuck assets See the [multi-swap flow](https://docs.houdiniswap.com/developer-hub/swap-flows/multi-swap) for the full sequence. - name: On-chain DEX or Bridge description: >- On-chain swaps signed and funded from the user's own wallet. Flow: [Get tokens](/api-reference/on-chain-dex-or-bridge/get-tokens) with `hasDex=true` → [Get quotes](/api-reference/on-chain-dex-or-bridge/get-quotes) with `types=dex` → [Get token approval data](/api-reference/on-chain-dex-or-bridge/get-token-approval-data) → send it and poll [Check token allowance](/api-reference/on-chain-dex-or-bridge/check-token-allowance) → [Get next chain signature](/api-reference/on-chain-dex-or-bridge/get-next-chain-signature) → [Create exchange](/api-reference/on-chain-dex-or-bridge/create-exchange) → [Confirm DEX transaction](/api-reference/on-chain-dex-or-bridge/confirm-dex-transaction) → [track the order](/api-reference/on-chain-dex-or-bridge/get-order-details). - `slippage` applies to DEX only - `markup` is not supported - name: Reference Data description: >- Optional lookups: supported chains, liquidity providers, and per-pair min/max swap amounts. Responses are cached and change rarely — safe to fetch once and reuse. Token ids come from `/tokens`, listed in each swap section above. - name: Partner Account description: >- Your orders, profile, earned commissions, withdrawals, volume analytics, and the rate-limit budget attached to your API key. Every endpoint is scoped to the partner that owns the key making the request. - name: System description: >- Service health. [Get system health](/api-reference/system/get-system-health) is unauthenticated and exempt from x402 payment — use it for uptime monitoring. paths: /dex/approve: post: tags: - On-chain DEX or Bridge summary: Get token approval data description: >- Returns what the wallet must approve before a DEX swap. Call this first — both arrays come back empty when the allowance already covers the swap. - `approvals` — transactions to send. After sending them, poll [Check token allowance](/api-reference/on-chain-dex-or-bridge/check-token-allowance) until it returns true. - `signatures` — EIP-712 permits to sign instead, when the token and provider both support EIP-2612 operationId: Approve parameters: [] requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/ApproveRequest' responses: '200': description: What the wallet must approve; both arrays empty if nothing is needed content: application/json: schema: $ref: '#/components/schemas/ApprovalResponse' examples: Example 1: value: approvals: - from: '0xb7dE6b6eEBF7401aFea5a49D6405C9048fEf2d40' to: '0xdac17f958d2ee523a2206206994597c13d831ec7' data: >- 0x095ea7b30000000000000000000000001111111254eeb25477b68fb85ed929f73a960582000000000000000000000000000000000000000000000000000000003b9aca00 fromChain: id: 6689b73ec90e45f3b3e5150a name: Ethereum shortName: ethereum shortNameV1: ETH kind: evm chainId: 1 enabled: true icon: https://api.houdiniswap.com/assets/networks/ETH.png created: '2024-07-06T10:21:18.000Z' explorerUrl: https://etherscan.io/tx/{txHash} addressUrl: https://etherscan.io/address/{address} addressValidation: ^0x[a-fA-F0-9]{40}$ tokenAddressValidation: ^0x[a-fA-F0-9]{40}$ signatures: [] '401': description: >- Credentials missing, malformed, or rejected — all return `INVALID_API_CREDENTIALS`. Sending only `partner-id` returns `PARTNER_ID_NOT_SUPPORTED`. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '402': description: >- Payment required — x402 protocol. The body is empty; what to pay is in the `payment-required` header. Not returned when you send an `Authorization` header. content: application/json: schema: $ref: '#/components/schemas/X402PaymentRequired' headers: payment-required: schema: type: string required: true '403': description: Access Denied content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '422': description: Validation Failed content: application/json: schema: $ref: '#/components/schemas/ValidationError' '429': description: Rate limit exceeded — back off and retry content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '500': description: Internal Server Error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' security: - apiKey: [] components: schemas: ApproveRequest: properties: quoteId: type: string description: Quote ID from a prior quote response. example: 69a02882f48d56c923119d95 addressFrom: type: string description: Address from which the amount will be deducted (EVM or Tron) example: '0xb7dE6b6eEBF7401aFea5a49D6405C9048fEf2d40' pattern: ^(0x[0-9a-fA-F]{40}|T[1-9A-HJ-NP-Za-km-z]{33})$ addressTo: type: string description: >- Destination address on the output chain. Only required by routes whose approval step signs the destination, currently HyperCore withdrawals. Format follows the output chain, so it is not restricted to EVM. example: 8jZnXYnZB1MJQG6zBXyouzcycsaPTrZtPXPHDNifjYaC usePermit: type: boolean description: >- Whether to use permit instead of approve. Defaults to true for swaps that support it. example: false required: - quoteId - addressFrom type: object additionalProperties: false ApprovalResponse: properties: approvals: items: $ref: '#/components/schemas/ApproveTransaction' type: array description: >- Transactions the wallet must send before the swap. Empty when the allowance already covers it. signatures: items: $ref: '#/components/schemas/ApprovalTypedData' type: array description: >- Messages to sign instead of sending an approval transaction, when the token and provider both support it. Pass the signed results to `signatures` on [Create exchange](/api-reference/private-and-standard-swaps/create-exchange). required: - approvals - signatures type: object additionalProperties: false ErrorResponse: properties: message: type: string code: type: string description: >- Machine-readable reason for the failure. Branch on this, not on `message` — messages are free to change. The value depends on the HTTP status. The common ones: - `400` — `BAD_REQUEST` - `401` — `INVALID_API_CREDENTIALS`, `PARTNER_ID_NOT_SUPPORTED` - `403` — `ACCESS_DENIED`, `FIXED_RATE_NOT_ALLOWED` - `404` — `NOT_FOUND`, `TOKEN_NOT_FOUND`, `TOKEN_DISABLED` - `409` — `ALREADY_SUBMITTED`, `STATIC_DEPOSIT_IN_USE` - `422` — `VALIDATION_ERROR`, `AMOUNT_TOO_LOW`, `INVALID_SWAP`, `FIXED_RATE_QUOTE_EXPIRED`, and most other request problems - `429` — `RATE_LIMIT_EXCEEDED` - `5xx` — `INTERNAL_SERVER_ERROR`, `PROVIDER_EXCHANGE_FAILED`, `SERVICE_UNAVAILABLE` New codes are added over time, so treat this as an open set: match the ones you handle and fall back to the HTTP status for the rest. requestId: type: string description: >- Unique id for this request. Quote it when contacting support — it is how we find the failure in our logs. required: - message - code type: object additionalProperties: false X402PaymentRequired: description: >- Body of a `402 Payment required`. Empty — `{}` — for API clients; a request that looks like a browser gets an HTML paywall page instead. This is the x402 payment protocol, not the normal error format, so there is no `code` or `message` to branch on. What to pay is always in the `payment-required` response header, in both cases: base64-encoded JSON whose `accepts[]` entries each carry the `network`, the `asset` to pay in, the `amount`, and the `payTo` address, alongside `maxTimeoutSeconds` and the x402 `scheme`. Sending `Authorization` skips the payment flow, so a 402 only reaches callers paying per request. An `apiKey` query param also skips it but is not a credential — those requests fail with `401 INVALID_API_CREDENTIALS`. properties: {} type: object additionalProperties: false ValidationError: properties: message: type: string code: type: string description: >- Machine-readable reason for the failure. Branch on this, not on `message` — messages are free to change. The value depends on the HTTP status. The common ones: - `400` — `BAD_REQUEST` - `401` — `INVALID_API_CREDENTIALS`, `PARTNER_ID_NOT_SUPPORTED` - `403` — `ACCESS_DENIED`, `FIXED_RATE_NOT_ALLOWED` - `404` — `NOT_FOUND`, `TOKEN_NOT_FOUND`, `TOKEN_DISABLED` - `409` — `ALREADY_SUBMITTED`, `STATIC_DEPOSIT_IN_USE` - `422` — `VALIDATION_ERROR`, `AMOUNT_TOO_LOW`, `INVALID_SWAP`, `FIXED_RATE_QUOTE_EXPIRED`, and most other request problems - `429` — `RATE_LIMIT_EXCEEDED` - `5xx` — `INTERNAL_SERVER_ERROR`, `PROVIDER_EXCHANGE_FAILED`, `SERVICE_UNAVAILABLE` New codes are added over time, so treat this as an open set: match the ones you handle and fall back to the HTTP status for the rest. requestId: type: string description: >- Unique id for this request. Quote it when contacting support — it is how we find the failure in our logs. fields: $ref: '#/components/schemas/FieldErrors' required: - message - code - fields type: object additionalProperties: false ApproveTransaction: properties: data: type: string description: >- Calldata to send. Encodes the approval for the amount this swap needs. to: type: string description: >- Send the transaction to this address — the contract of the token being approved. from: type: string description: >- Wallet that must send the transaction — the `addressFrom` you supplied. fromChain: $ref: '#/components/schemas/Chain' description: Chain the transaction runs on. required: - data - to - from - fromChain type: object additionalProperties: false ApprovalTypedData: properties: data: $ref: '#/components/schemas/EIP712TypedData' description: The EIP-712 payload for the wallet to sign. type: $ref: '#/components/schemas/SignatureType' description: >- `single` — sign it and you are done. `chained` — sign it, then call [Get next chain signature](/api-reference/on-chain-dex-or-bridge/get-next-chain-signature) for the next one. totalSteps: type: number format: double description: >- How many signatures this chain needs in total. `1` for a single signature. step: type: number format: double description: Which signature this is, counting from 1. isComplete: type: boolean description: >- True on the last signature of the chain — stop asking for more once you see it. key: type: string description: >- Identifies this signature. Pass it as `key` to [Get next chain signature](/api-reference/on-chain-dex-or-bridge/get-next-chain-signature) to fetch the next step. swapRequiredMetadata: $ref: '#/components/schemas/Record_string.any_' description: >- Provider data attached to this signature. Send it back unchanged with the signed result — the swap fails without it. required: - data - type - totalSteps - step - isComplete - key type: object additionalProperties: false FieldErrors: properties: {} type: object additionalProperties: properties: value: {} message: type: string required: - message type: object Chain: properties: icon: type: string description: Chain icon URL. addressValidation: type: string description: >- Regex a wallet address on this chain must match. Use it to validate `addressTo` before creating an exchange. tokenAddressValidation: type: string description: Regex a token contract address on this chain must match. id: type: string created: type: string format: date-time modified: type: string format: date-time name: type: string description: Readable chain name, e.g. `Bitcoin`. shortName: type: string description: >- The chain's identifier. Pass this wherever an endpoint takes a chain, e.g. `ethereum`. memoNeeded: type: boolean nullable: true description: >- True when an address on this chain needs a memo or destination tag, e.g. XRP or TON. Send it as `destinationTag` for the payout address, or `refundExtraId` for the refund address. hashUrl: type: string description: >- Explorer link for a transaction hash, when it differs from `explorerUrl`. explorerUrl: type: string description: >- Template for a transaction link — substitute `{txHash}`, e.g. `https://blockchair.com/bitcoin/transaction/{txHash}`. addressUrl: type: string description: >- Template for an address link — substitute `{address}`, e.g. `https://blockchair.com/bitcoin/address/{address}`. priority: type: number format: double description: Display order — lower sorts first. kind: type: string description: >- Chain family, e.g. `evm`, `sol`, `bitcoin`, `xmr`, `ltc`. Determines the address format and which on-chain steps a DEX swap needs. chainId: type: number format: double nullable: true description: EVM chain id, e.g. `1` for Ethereum. Null on non-EVM chains. enabled: type: boolean description: False when the chain is temporarily not routing swaps. shortNameV1: type: string description: The chain's name in the v1 API. Use `shortName` instead. required: - icon - addressValidation - tokenAddressValidation - id - created - name - shortName - explorerUrl - addressUrl - kind - enabled - shortNameV1 type: object additionalProperties: false EIP712TypedData: properties: domain: $ref: '#/components/schemas/TypedDataDomain' types: $ref: '#/components/schemas/Record_string.TypedDataField-Array_' primaryType: type: string message: $ref: '#/components/schemas/Record_string.any_' required: - domain - types - primaryType - message type: object additionalProperties: false SignatureType: enum: - single - chained type: string Record_string.any_: properties: {} additionalProperties: {} type: object description: Construct a type with a set of properties K of type T TypedDataDomain: properties: name: type: string version: type: string chainId: type: number format: double verifyingContract: type: string salt: type: string type: object additionalProperties: false Record_string.TypedDataField-Array_: properties: {} additionalProperties: items: $ref: '#/components/schemas/TypedDataField' type: array type: object description: Construct a type with a set of properties K of type T TypedDataField: properties: name: type: string type: type: string required: - name - type type: object additionalProperties: false securitySchemes: apiKey: type: apiKey name: Authorization in: header description: >- Send `Authorization: :` — joined by a colon, raw. No `Bearer` prefix, no base64. [Get your credentials](https://docs.houdiniswap.com/developer-hub/getting-started/authentication) ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.