Our CSV import was our most powerful feature and our biggest churn driver.

We tracked what users did in their first session and correlated with 30-day retention.

Users who imported a CSV: 18% of new signups, 74% retained at 30 days

Users who did not import: 82% of signups, 31% retained

A massive difference. CSV import was the single strongest predictor of retention we had ever found. We promoted it everywhere.

Then we looked at the users who started an import and did not finish. 61% of import attempts failed or were abandoned. Among those users, 30-day retention was 9%. Lower than users who never tried.

The feature that predicted retention was also the feature that drove people away when it failed. And it failed 61% of the time because it required exact column headers, exact date formats, and exact encoding — none of which we told users until after they uploaded.

We built a column-mapping step that let users match their headers to ours, and auto-detected date formats. Import completion rose from 39% to 81%. Retention among importers rose from 74% to 86%.

What is your highest-retention feature, and what happens to the people it rejects?