Vercel Flags Adds Support for Timestamp Attributes in Entity Targeting

Vercel Flags now supports timestamp attributes for entities, which represent users, teams, devices, or requests evaluated by a flag. This feature allows developers to implement time-sensitive logic, such as showing a campaign page only between two dates, running a Black Friday promotion, or targeting users who registered before a specific cutoff.

Configuration and Implementation

Timestamp attributes can be configured in the Vercel dashboard or via the CLI. In the dashboard, users navigate to Flags, select Entities, and set the attribute data type to timestamp. Alternatively, the CLI can define the attribute directly.

Regardless of the configuration method, the application must provide the attribute's value when evaluating a flag. The entity and attribute names must match the configuration, and the value must be a Unix epoch timestamp in milliseconds. A common implementation uses Date.now() within a dedupe() function to ensure consistent time values across flag evaluations in a single request.

Targeting Rules

Once configured, timestamp attributes enable specific targeting rules in the dashboard or CLI. Supported comparisons include:

• is after
• is at or after
• is before
• is at or before

The dashboard's date and time picker uses the user's local timezone, while CLI rules use keywords like after, at-or-after, before, and at-or-before.