> ## Documentation Index > Fetch the complete documentation index at: https://requestly-mintlify-changelog-requestly-past-week-38456.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # GraphQL Support > Learn to modify GraphQL API requests and responses using Requestly to debug and test GraphQL APIs. *** Unlike REST APIs, GraphQL APIs provide a flexible approach to querying and mutating data through a single endpoint. They allow clients to specify exactly what data is needed, reducing over-fetching and under-fetching issues common with REST APIs. GraphQL APIs can be modified to customize requests and responses for testing and debugging. This guide provides detailed steps to achieve this using Requestly. ## Modifying GraphQL Responses In GraphQL, client interactions are typically managed through a single HTTP endpoint. The specific operation to execute is often indicated by the `operationName` field in the request payload. **Example Request** ```bash theme={null} POST { "operationName": "getUsers", "query": ` query getUsers { users { id email } } ` } ``` To modify the response of a GraphQL API: ### Steps to Modify API Response Navigate to the HTTP Rules section in the web or desktop app. Click on "+ New Rule" and select **Modify API Response**. Choose "GraphQL API" as the Resource Type. In the **GraphQL Operation (Request Payload Filter)** section: * Enter **Key** as `operationName`. * Enter **Value** as the operation name you want to target (e.g., `getUsers`). Define the new response you want to serve for the specified operation. Click **Save** to store the rule and toggle it ON to apply the changes. Validate the rule by sending a request matching your conditions and verifying the modified response. For additional details, visit the Modify API Response Rule Page. **Notes** * The **Key** represents the JSON key in the request payload and supports nested paths. For example: * If `operationName` is located at `data.operationName`, specify `data.operationName`. * For array payloads, such as `[{"operationName": "value"}]`, use `0.operationName` as the key. * If the request does not include `operationName`, select **Resource Type** as "REST API" and use **Dynamic (JavaScript) Mode** to filter and modify the response. ### Example Without `operationName` In cases where the operation is specified within the `query` field: ```bash theme={null} POST /graphql { "query": ` query getUsers { users { id email } } ` } ``` You can modify the response using a JavaScript snippet: ```jsx theme={null} function modifyResponse(args) { const { url, response, requestData, responseJSON } = args; if (requestData.query?.includes("query getUsers")) { console.log("Requestly: Modifying response", { query: requestData.query }); return { ...responseJSON, custom: true }; } return response; } ``` *** ## Modifying GraphQL Requests If you need to alter the GraphQL query or its variables, use the **Modify Request Body** rule to change the request payload dynamically. ### Steps to Modify Request Body Navigate to the HTTP Rules tab in the web or desktop app. Click on "+ New Rule" and select **Modify Request Body**. Choose "GraphQL API" as the Resource Type. In the **GraphQL Operation (Request Payload Filter)** section: * Enter **Key** as `operationName`. * Enter **Value** as the operation name you want to target (e.g., `getUsers`). Define the new Request you want to serve for the specified operation Click **Save** to store the rule and toggle it ON to apply the changes Validate the rule by sending a request matching your conditions and verifying the modified response. For additional details, visit the Modify Request Rule Page.