## Custom Fields

The `/omni/start` endpoint can receive a key-value map in the `customFields` parameter. Go to **Configuration** > **General** > **Custom Fields** to define these key-values.

Custom fields are displayed on a single session page.

## Use Cases

The two most common ways to use custom fields are crosschecking collected data and passing internal identifiers.

### Crosscheck Data

If you already have a user's first and last name in your system, you can use that to ensure the person doing a verification matches the existing user. To do this, set up a crosscheck between the data from the ID and the data that exists in your system:

1. Add a Process node to your Workflow; select **Cross Check** from the drop-down.

2. Configure your Cross Check step:
   1. Click **Add new comparison**.
   2. Enter a _**CrossCheck Name**_. Do not include special characters in the name.
   3. Use the drop-downs to select sources and fields to compare. One source should be _CUSTOM_FIELDS_ and the other is usually _ID_.
   4. Set the **Comparison Severity**. This determines how high the match must be in order to pass.
   5. Click **Save Comparison**.
   6. You can continue adding more comparisons to the same Cross Check node as needed, or return to the Workflow.

3. Add a [Condition](https://developer.incode.com/update/docs/conditionals#/) to set the Yes and No paths after the Cross Check node. For example, if you are checking that the first names match, configure the Condition so that if the first name Cross Check you added matches, the result is OK.

### Pass Internal Identifiers, Tags, and Markers

Internal identifiers, tags, and markers can be used to distinguish different Sessions or connect with internal systems.

#### External Customer Id

For a connection between the Incode Session and your Session, use the `externalCustomerId` parameter. This is an optional string parameter in the `omni/start` call.

#### Configuration Id

This is the ID of a Workflow the user will go through. To find the ID of a Workflow, navigate to the Workflows page and find the Workflow you want. In the Actions column, click **...** > **Copy ID**.

#### Redirect URL

Override the **_Redirect URL_** from a Workflow's settings if you want to make a redirect more granular; for example, per user or other group. Use the format: [https://your.url](https://your.url/).