> ## Documentation Index > Fetch the complete documentation index at: https://docs.zerodash.studio/llms.txt > Use this file to discover all available pages before exploring further. # Rollback transaction > Cancels a bet and returns the stake to the player. Credit and rollback are **mutually exclusive**: a given bet is settled by one or the other, never both. **Important —** Like credit, rollback must not require a live player session and is retried for up to 3 days. If you have already rolled back this `referenceTransactionId`, return `200 OK` with your stored result — see [Idempotency](/wallet/idempotency). ## OpenAPI ````yaml api-reference/callbacks.json POST /rollback openapi: 3.1.0 info: title: Zero-Dash Wallet Callbacks version: 1.0.0 summary: >- The wallet API that you implement and Zero-Dash calls to authorize players and move money. description: >- **You implement these five endpoints. Zero-Dash calls them.** This is the inverse direction of the [Customer API](/api-reference/customer/list-games): here Zero-Dash is the client and your platform is the server. Mount them under any base path you like — the full path you register is what gets signed. All endpoints must be RESTful, accept and return JSON, and be served over HTTPS with a valid TLS certificate. Before you write a line of code, read [Wallet integration](/wallet/overview), [Amounts and currencies](/wallet/amounts) and [Idempotency](/wallet/idempotency). **Tip —** Use the playground on these pages to fire signed requests at **your own** implementation: set the `host` server variable to your callback host. contact: name: Zero-Dash Integrations email: info@zerodash.studio servers: - url: https://{host} description: >- Your wallet host. Point this at your own environment to test your implementation. If you mount the endpoints under a path prefix (for example /zerodash/v1), include it in the host value — the full registered path is what gets signed. variables: host: default: wallet.example-operator.com description: The host you register with Zero-Dash, including any path prefix. security: - signature: [] timestamp: [] tags: - name: Wallet description: Player authorization and the money movements of a game round. - name: Troubleshooting description: Endpoints Zero-Dash uses to reconcile state after a failure. paths: /rollback: post: tags: - Wallet summary: Rollback transaction (revert) description: >- Cancels a bet and returns the stake to the player. Credit and rollback are **mutually exclusive**: a given bet is settled by one or the other, never both. **Important —** Like credit, rollback must not require a live player session and is retried for up to 3 days. If you have already rolled back this `referenceTransactionId`, return `200 OK` with your stored result — see [Idempotency](/wallet/idempotency). operationId: rollback requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/RollbackRequest' example: playerId: acct_8f2c19 transactionId: test-transaction-1115 referenceTransactionId: test-transaction-1112 gameId: lucky-duck gameRoundId: round-1234 stake: amount: 1 currency: USD reason: paid responses: '200': description: Bet reverted and the stake returned. content: application/json: schema: $ref: '#/components/schemas/TransactionResponse' example: operatorTransactionId: op-tx-55903 balance: amount: 96 currency: USD updatedAt: '2026-01-29T14:05:29.678Z' createdAt: '2026-01-29T14:05:29.678Z' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '404': description: The bet transaction to revert was not found. content: application/json: schema: $ref: '#/components/schemas/Error' example: message: transaction to revert not found '500': $ref: '#/components/responses/InternalError' components: schemas: RollbackRequest: type: object required: - playerId - transactionId - referenceTransactionId - gameId - gameRoundId - stake properties: playerId: type: string description: Player account ID. transactionId: type: string description: >- Zero-Dash ID of this rollback transaction. Use it as your idempotency key. referenceTransactionId: type: string description: '`transactionId` of the bet to revert.' gameId: type: string description: Slug of the game the round belongs to. examples: - lucky-duck gameRoundId: type: string description: Same value as the debit being reverted. examples: - round-1234 stake: $ref: '#/components/schemas/Amount' description: Stake of the original bet, to be returned to the player. reason: $ref: '#/components/schemas/Reason' freeRoundData: $ref: '#/components/schemas/FreeRoundData' TransactionResponse: type: object required: - operatorTransactionId - balance properties: operatorTransactionId: type: string description: >- Your internal transaction ID. Stored by Zero-Dash for troubleshooting only. balance: $ref: '#/components/schemas/Balance' createdAt: type: string format: date-time description: >- Transaction creation date (ISO-8601 UTC). Defaults to the time of processing when omitted. Error: type: object description: Error body. Use this shape wherever possible so failures are actionable. properties: message: type: string description: Human-readable explanation of the failure. Amount: type: object required: - amount - currency description: >- A monetary value as a **decimal**, never in minor units. Crypto is capped at 8 decimal places. properties: amount: oneOf: - type: number - type: string description: Decimal value, for example `12.45` USD or `0.00000123` BTC. examples: - 1 currency: type: string description: ISO-4217 currency code. examples: - USD Reason: type: string description: >- Type of the bet. `paid` is real money; `freeround` is a free round — each free spin is a separate bet with its own debit call. enum: - paid - freeround FreeRoundData: type: object required: - campaign - value description: Present only when `reason` is `freeround`. properties: campaign: type: string description: Campaign code the free round belongs to. examples: - freeround-campaign-1 value: $ref: '#/components/schemas/Amount' description: Nominal value of one free round, as configured on the campaign. Balance: type: object required: - amount - currency description: The player's balance **after** the operation was applied. properties: amount: oneOf: - type: number - type: string description: >- Most recent decimal balance, for example `12.45` USD or `0.00000123` BTC. examples: - 95 currency: type: string description: ISO-4217 currency code. examples: - USD updatedAt: type: string format: date-time description: When the balance was last updated (ISO-8601 UTC). responses: BadRequest: description: Invalid request payload format. Include an explanation in the body. content: application/json: schema: $ref: '#/components/schemas/Error' example: message: missing field gameRoundId Unauthorized: description: >- Signature mismatch, stale timestamp, or source IP outside the Zero-Dash allowlist. content: application/json: schema: $ref: '#/components/schemas/Error' example: message: invalid signature InternalError: description: Internal server error. content: application/json: schema: $ref: '#/components/schemas/Error' example: message: internal error securitySchemes: signature: type: apiKey in: header name: X-Zd-Signature description: >- Hex-encoded `HMAC-SHA512(apiPath|timestamp|data, secretKey)` computed by Zero-Dash. **Recompute it and compare before doing anything else.** See [Request signature](/security/signature). timestamp: type: apiKey in: header name: X-Zd-Timestamp description: >- Unix time in **milliseconds**, and the exact value that was signed. Reject requests older than 5 minutes. ````