Evaluation metrics for Vercel Flags
By Steven Van ·
The new evaluations view groups and filters by variant, environment, client and more, and requires @vercel/flags-core 1.6.0 or later.
Vercel Flags now shows a live evaluations chart on each flag's detail page, plotting evaluations per minute over time and marking flag version changes directly on the chart so a shift in evaluations can be tied to a specific configuration change.
- Evaluations can be grouped and filtered by variant, reason, environment, SDK key, client, and reporting project.
- Custom clients can set a new clientName property on the client initializer to appear as their own group.
- The full evaluation view, opened from the chart, holds up to 90 days of history at a granularity down to one minute.
This makes it possible to confirm rollout percentages match what's being served, separate targeted matches from default fallbacks, and see which projects are using a given flag. It requires @vercel/flags-core 1.6.0 or later: clients on older versions still evaluate flags correctly, but their evaluations won't appear in the metrics, and the chart shows a warning until they're updated. Metrics appear automatically, with no additional configuration. Read more in the evaluation metrics documentation.