> ## Documentation Index > Fetch the complete documentation index at: https://docs.gr4vy.com/llms.txt > Use this file to discover all available pages before exploring further. # Anti-fraud > Use decisions and scores from anti-fraud services in Flow rules to manage risk in your transaction flow. As part of [Flow](/guides/dashboard/flow) the system allows you to build rules which use decisions and scores from anti-fraud services. For detailed information on setting up and configuring specific anti-fraud providers, see the anti-fraud services in the [connection catalog](/connections/catalog?category=anti-fraud). Cybersource, Forter, Riskified, Sardine, and Sift are supported. Flow rule with an anti fraud decision You can use these scores and decisions for [card transactions](/guides/dashboard/flow/card-transactions) to evaluate the risk of a transaction and take appropriate actions to, for example, force 3-D Secure, decline a transaction, or route to a specific payment service. ## How does it work? For every transaction, your [**Primary**](#connection-mode) anti-fraud service is only called **once**. When a request is made for a transaction, your active anti-fraud provider is only called once, assuming a rule is triggered for which an anti-fraud score or decision is the condition. This feature prevents incurring any extra cost by calling your anti-fraud service multiple times, or calling your service unnecessarily if the rule is not triggered. ## Connection mode Each of your configured anti fraud services can be set to a **Primary**, [**Silent**](/guides/features/anti-fraud/silent-mode), or **Inactive** mode. | Mode | Description | | :- | :- | | **Primary** | Traffic is processed through this connector's fraud checks. It returns an approval or decline, which determines whether the transaction continues. Only one primary connector can be configured at any time. | | [**Silent**](./silent-mode) | Traffic is processed through this connector, but its decision is not enforced. Results are logged for learning/analysis only. | | **Inactive** | No traffic is processed through this connector, but it is available to be re-activated at any time. | ## Anti-fraud decisions Gr4vy maps each provider's response to one of the following decisions. The transaction's `anti_fraud_decision` field holds the decision from the Primary service, and the **Anti-fraud decision** condition in Flow matches on the same values. | Decision | Flow label | Description | | :- | :- | :- | | `accept` | Accept | The service accepted the transaction. | | `reject` | Reject | The service rejected the transaction. | | `review` | Review | The service flagged the transaction for a [manual review](/guides/features/anti-fraud/reviews). | | `error` | Error | The service returned an error decision, or a decision that Gr4vy can't map to another value. | | `exception` | Error (network error) | The call to the service failed, for example because it timed out or returned a server error. | | `skipped` | Skipped (unable to get decision) | Gr4vy couldn't get a decision, for example because the service rejected the request. | | `pending` | Not applicable | The check hasn't completed yet. | `anti_fraud_decision` is `null` when no anti-fraud check ran for the transaction. For a `review` decision, the field keeps the value `review` after the review is resolved. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.