CSV (Comma-Separated Values) is one of the most universal data file formats. Despite its name, CSV files can use different delimiters — semicolons are common in European locales, tabs appear in TSV files, and pipe characters (|) appear in some database exports. A good CSV viewer handles all of these transparently.
What is a CSV file?
A basic CSV file looks like this:
name,age,city,salary
Alice,32,Hanoi,15000000
Bob,28,HCMC,12000000
Charlie,35,Da Nang,18000000
The first row is typically the header row, defining column names. Each subsequent row is a record. When a field value contains the delimiter character, it must be wrapped in double quotes:
name,bio
Alice,"Software engineer, consultant, and writer"
Bob,"Fan of commas, semicolons, and other punctuation"
Common sources of CSV files
- Excel exports: File → Save As → CSV (Comma delimited) or Text (Tab delimited)
- Google Sheets: File → Download → Comma-separated values
- Database query results: Most databases and query tools offer CSV export
- API responses: Many APIs support
?format=csvorAccept: text/csv - E-commerce reports: Shopify, WooCommerce, and similar platforms export orders and products as CSV
- Analytics downloads: Google Analytics, Mixpanel, Amplitude, and similar tools export CSV
- CRM exports: Salesforce, HubSpot, and most CRMs support CSV export
Common CSV problems and solutions
Delimiter confusion
If you open a CSV in Excel and see all data in a single column, the delimiter probably doesn't match Excel's regional settings. European versions of Excel expect semicolons by default; US versions expect commas. Manually specify the delimiter during import (Data → From Text/CSV in Excel) or use a viewer that auto-detects it.
Encoding issues (mojibake)
CSV files with non-ASCII characters (Vietnamese, Chinese, accented European characters) must be saved as UTF-8. When Excel on Windows opens a UTF-8 CSV without recognizing the encoding, it shows garbled characters (called "mojibake"). Solution: import via Data → From Text/CSV and explicitly choose UTF-8 encoding, or use a browser-based viewer that always handles UTF-8 correctly.
Quoted fields with embedded delimiters
The standard handles this with double-quote wrapping:
"Ho Chi Minh, City",Vietnam,+84
A naive line.split(',') in code does not handle this correctly. Always use a proper CSV parser library.
Numbers as text
CSV has no type system — everything is a string. If the first column contains IDs like 007, Excel may strip the leading zero when opening the file. Use type inference carefully, or treat all values as strings when precision matters.
BOM (Byte Order Mark)
Excel sometimes prepends a BOM (\uFEFF) at the start of UTF-8 CSV files it generates. This is invisible in most text editors but causes issues in some parsers. A good CSV parser strips the BOM automatically.
Working with large CSV files
Column statistics first: Before scrolling through thousands of rows, check the statistics panel for each column — min, max, average, unique count, and empty count give a high-level picture of the data distribution.
Filter before analyzing: Narrow down to the relevant subset using the filter box before doing more detailed analysis. Filtering to 50 relevant rows is more productive than scanning 10,000.
Sort strategically: Sorting by a numeric column reveals the range and extremes. Sorting by a text column reveals unique values and typos. Sorting by a date column shows the time span.
Exporting to other formats
| Format | Best for |
|---|---|
| CSV | Re-importing into spreadsheets or databases |
| JSON | Feeding into JavaScript code or APIs |
| TSV | Import into tools that expect tab separation |
| Markdown table | Including data in documentation or README files |
How to view CSV files free
- Go to CSV Viewer
- Drag and drop your .csv file or click Upload CSV
- The delimiter is auto-detected (comma, semicolon, tab, or pipe)
- Click any column header to sort; click again to reverse
- Use the filter box to search all columns simultaneously
- Click the chart icon on a column header to see column statistics
- Enable Edit mode to modify cells directly in the browser
- Export as CSV, JSON, TSV, or Markdown table
Your file is never uploaded to a server — all processing runs locally in your browser.