> For the complete documentation index, see [llms.txt](https://docs.tpi.dev/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tpi.dev/digirunner-open-source/most-common-use-cases/obtaining-api-keys-and-calling-apis.md).
# Obtaining API Keys and Calling APIs
### Obtaining API Keys
1. Go to **Application Forms** > **API Key**, and click on the **Details** icon  of the client to apply.
2. Enter the API Key list of that user and click **Apply** to enter the apply page.
3. Fill in the required fields.
4. Enter the keyword to search in the **Select API** field, and select the API to apply.
5. Click **Save** to complete the application of the API Key.
6. Go to **Application Forms** > **Applications**, locate the API Key application form to sign-off in the list of application forms.
7. Click on the **Submit for Review** icon, after the confirmation window pops up, click **Confirm** to complete the submission for review.
8. Click the **Pending order** tab to enter the pending order list, click on the **Sign-off** icon to enter the sign-off page, and click **Approve** to complete the first review.
9. Click on the **Sign-off** icon to enter the sign-off page, and click **Approve** to complete the second review to obtain the API Key.
10. Go to **System Information** > **API Key Approval History** to view the API Key applied today.
### Calling APIs with the API Key
APIs registered in the system can use different OAuth Grant Type for verification, including: Client Credentials, Password, Basic, Auth and DGRK.
1. In the **Authorization** field, select **DGRK**.
2. In the **API Key** field, fill in the public key obtained from the email or database.
3. In the **Secret Key** field, fill in the private key obtained from the email or database.
4. Click **Test** to view the response. In this example, the status code is *200*, indicating that the body contains the data defined by the API.
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