COLUMN HARBOR · CSV CHECKER & GUIDES
Check your CSV before
Excel changes it.
Catch fragile IDs, mismatched columns and ambiguous dates.
Keep the original values in sight, before you import.
WHEN THE NEXT EXPORT ARRIVES
What changed between these two CSV files?
Compare by ID, even when rows move. Review added, removed and changed records, with duplicate or blank keys kept separate.
01
Your source file
UTF-8 CSVSynthetic example
Your CSV stays in this browser. No file upload.
UTF-8 · 20,000 data records · 250,000 cells max.
02
Before you import
8 things to review
3 data records · 4 columns · values kept as text
RECORD 2 / COL 1
00123Numeric-looking text has a leading zero. Import this column as Text to preserve the identifier.
How to handle this ↗RECORD 2 / COL 2
123456789012345616 or more digits. Excel number conversion can lose precision; import identifiers as Text.
How to handle this ↗RECORD 2 / COL 3
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.
RECORD 3 / COL 1
00456Numeric-looking text has a leading zero. Import this column as Text to preserve the identifier.
How to handle this ↗RECORD 3 / COL 2
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.
SOURCE PREVIEW First 5 records · original text 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 |
CHOOSE A DATA TASK
Work with the file. Keep the result.
Compare lists or files, clean and split CSV records, convert formats, preserve IDs in Excel and reuse cleanup settings.
NEW · YOUR EVERYDAY DATA DESK
Keep your spreadsheet toolkit close.
Compare lists, clean CSV files, remove duplicates and keep useful formulas in one place. Your data stays in your browser.
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Follow the Excel Academy from cells and formulas to PivotTables and Power Query, with practice data and worked answers.
Open Excel Academy ↗FROM THE FIELD GUIDES
Practical answers for everyday data work.
01
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 ↗14Excel TRIM Not Working? Find and Remove Hidden Spaces
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 ↗35Power Query Merge Creates Duplicate Rows? Fix Extra Rows
An Excel query with four sales can become six rows after you expand a merge. This is often a valid consequence of the selected keys, not a random refresh bug. The practical question is whether one output row should represent a sale, an address, or a sale-address pair.
Read the guide ↗A QUICK FIELD NOTE
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.