CSV (Comma-Separated Values) is the most common format for data exchange between applications, but "simple" is deceptive. Real-world CSV files are riddled with inconsistencies that break imports, corrupt data, and waste hours of debugging time.
1. Encoding Issues
The most frustrating CSV problem is character encoding. A file created on a Japanese Windows machine might use Shift-JIS encoding, while your Linux server expects UTF-8. Special characters like accents (é, ü), currency symbols (€, £), and CJK characters become garbled. Fix: Always save and transmit CSV files as UTF-8 with BOM (Byte Order Mark) for maximum compatibility.
2. Inconsistent Delimiters
Not all "CSV" files use commas. European tools often use semicolons (because commas serve as decimal separators in many European locales). Tab-separated values (TSV) are also common. Fix: Detect the delimiter before parsing — look at the first few lines and count delimiter candidates.
3. Unescaped Special Characters
Fields containing commas, quotes, or newlines must be properly quoted. The value Smith, John must appear as "Smith, John" in CSV. Double quotes within quoted fields must be escaped as two double quotes. Fix: Always use a proper CSV parser library — never split on commas manually.
4. Inconsistent Date Formats
Is "01/02/2026" January 2nd or February 1st? Different columns might use MM/DD/YYYY, DD/MM/YYYY, YYYY-MM-DD, or text formats like "Jan 2, 2026". Fix: Standardize on ISO 8601 (YYYY-MM-DD) which is unambiguous and sorts correctly.
5. Missing Values
Missing data appears as empty strings, "NULL", "N/A", "n/a", "-", "0", or whitespace. Each requires different handling. Fix: Define a canonical representation (empty string or "NULL") and normalize before processing.
6-10: More Common Issues
6. Trailing whitespace in fields causing failed lookups. 7. Duplicate rows from repeated exports. 8. Inconsistent casing ("New York" vs "new york" vs "NEW YORK"). 9. BOM characters appearing as garbage at the start of the file. 10. Mixed data types in a single column (numbers mixed with text).
Use our CSV to JSON Converter to validate CSV structure, or our CSV to Excel Converter to inspect data in a spreadsheet format.