Your IDs should stay IDs.

Check CSV files before Excel changes leading zeros, long numbers or dates.

Up to 2 MB · 10,000 rows · 200 columns · 200,000 cells. Choose the encoding used by your source.

Choose a file to inspect. Files stay on this device.

This preserves source values. Numbers remain text; formulas do not execute. No automatic data correction.

Risk preview

Warnings indicate possible conversion risks, not confirmed errors. Showing at most 100 examples.

Risk	Row	Column	Original value