CSV Helper

Free tools for checking, converting and comparing CSV files. They do not repair Excel workbooks or execute spreadsheet formulas.

🔒 Files are processed only inside your browser and are never sent to a server.

• CSV CheckerFinds broken characters, column mismatches and quote errors, with line numbers.
• CSV ↔ JSON ConverterConvert CSV to JSON and JSON to CSV. Reads Korean Excel CSV files too.
• Remove Duplicate RowsKeeps the first of rows that match on the columns you choose.
• Encoding Converter (CP949 ↔ UTF-8)Convert Korean Excel CSV (CP949) and UTF-8 files both ways.
• JSON Formatter & ValidatorPretty-prints JSON and points to errors by line and column.
• Character & Byte CounterCounts characters with and without spaces, plus UTF-8 and CP949 bytes.

Guides

• CSV row count doesn't match? Count records, not text linesA supplier says an export contains two records, but your text editor shows four lines. Before deleting blank-looking lines or merging cells, check whe
• CSV opens in one column? Check for a semicolon delimiterYou receive a CSV export, open it, and see id;memo;count in a single header cell. The file may use semicolons while the reader expects commas. Changin
• Removing CSV duplicates? Check blank order IDs before deleting rowsTwo rows with the same order ID can describe different line items. Two rows with blank order IDs can also be separate records. If a deduplication remo
• CSV date 03/04: March 4 or April 3?03/04/2026 means March 4 in month/day/year order and April 3 in day/month/year order. A successful date conversion does not prove that the date has th