Check your CSV before
Excel changes it.
Catch fragile IDs, mismatched columns and ambiguous dates.
Keep the original values in sight, before you import.
Your source file
UTF-8 CSVYour CSV stays in this browser. No file upload.
Before you import
8 things to review
3 data records · 4 columns · values kept as text
00123Numeric-looking text has a leading zero. Import this column as Text to preserve the identifier.
How to handle this ↗123456789012345616 or more digits. Excel number conversion can lose precision; import identifiers as Text.
How to handle this ↗03/04/2026Looks like a date. Check the intended date order and locale, or import as Text. This is a pattern check, not date validation.
00456Numeric-looking text has a leading zero. Import this column as Text to preserve the identifier.
How to handle this ↗987654321098765416 or more digits. Excel number conversion can lose precision; import identifiers as Text.
How to handle this ↗Showing 5 of 8 findings; report retains up to 500 with full values. Record 1 is the header. Checks flag possible risks, not confirmed corruption or compatibility with every importer. The report may contain sensitive source values.
| sku | product_id | ship_date | customer |
|---|---|---|---|
00123 | 1234567890123456 | 03/04/2026 | Müller, Ana |
00456 | 9876543210987654 | 2026-04-15 | Jordan |
00789 | ABC-42 | 2026-05-01 | Sam |
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CSV Opens in One Column in Excel? Fix Comma or Semicolon Imports
If a CSV file opens in one column in Excel, the file separator and the import settings may not agree. This guide shows two repairs: import the original file with an explicit delimiter, or split intact text already in column A. The worked example includes a comma inside a description and a semicolon inside quotes, so you can check more than whether columns appeared.
Read the guide ↗05Keep Leading Zeros in Excel CSV Imports and Exports
If 00123 becomes 123 when you open a CSV, or the zeros seem to disappear again after saving, check the file before changing its formatting. The source text and the values Excel displays can differ.
Read the guide ↗14TRIM Not Working? Remove Hidden Spaces in Excel and Sheets
If TRIM leaves a visible gap or a lookup still fails after cleanup, the cell may contain a nonbreaking space rather than an ordinary space. Identify the character and choose whether internal spacing should change.
Read the guide ↗23CSV to JSON in Python: Preserve Leading Zeros and Empty Fields
To convert CSV to JSON in Python without losing leading zeros, keep identifier fields as strings. Empty CSV fields need a separate decision: an empty string, JSON null, and a missing property are different outputs. This guide includes a complete local Python script, a two-row sample, and both string-preserving and typed results.
Read the guide ↗A CSV stores values. Excel interprets them.
A product ID such as 00123 can still be intact in your file even when a spreadsheet displays 123. This checker shows the text actually present, then flags values that deserve a deliberate import choice. It cannot recover digits already overwritten.