CSV encoding fixer
Drop a CSV file to detect its encoding and delimiter, preview it, and download a copy that opens correctly in Excel.
Calculation and conversion of the text and files you enter happen in your browser, and the tool does not send your original input or results to a server. For traffic related to visit statistics and ads, see the privacy policy.
How to use it
- Drag your CSV file onto the box above, or click the box and choose the file. The file stays on your computer.
- Check the summary and the preview of the first 20 rows. If the text looks garbled, or the columns are not split correctly, pick the right encoding or delimiter under Read as instead of Auto.
- Choose an output: Excel (UTF-8 with BOM, comma) for opening in Excel, or UTF-8 (no BOM) for programs and databases. You can also change the delimiter.
- Press Download. A new file named after the original is saved; your original is not touched.
Examples
Korean text turns into question marks in Excel
A CSV exported as UTF-8 without a BOM shows Korean as garbage when opened in Excel for Windows. Drop the file here, keep the Excel output, and download. The copy has the three-byte BOM that tells Excel the file is UTF-8, and the Korean text opens correctly.
A file from a Korean system opens as nonsense in a UTF-8 tool
Banks, government sites and older Korean software often export EUC-KR (CP949). The tool detects that automatically and converts to UTF-8, so the same file now reads correctly in Python, databases and web apps.
- Input
C0 CC B8 A7 2C B3 AA C0 CC (EUC-KR bytes)
- Result
이름,나이 (after conversion to UTF-8)
Details
A CSV file is only text, but the file does not say which character encoding that text uses. Excel has to guess, and for files without a byte order mark (BOM) it usually assumes the legacy code page of your Windows installation. A UTF-8 file with Korean, Japanese or accented letters then appears as garbled symbols, while an EUC-KR file opened in a UTF-8 tool shows replacement characters. This tool reads the raw bytes to work out the encoding and shows you the result before you save anything.
Detection works in order. A BOM settles it immediately. Without one, the tool checks whether the whole file is valid UTF-8, which is a strong signal because Korean text in EUC-KR almost never happens to form valid UTF-8 by accident. If it is not, the file is read as EUC-KR (CP949) and judged by how many bytes cannot be decoded and how much of the text is Hangul. When the evidence is weak, the tool says so and lets you choose the encoding by hand.
The delimiter is guessed by reading the first rows with each candidate (comma, tab, semicolon and pipe) while respecting quotes, and picking the one that splits every row into the same number of columns. Fields are parsed as RFC 4180 describes: a field in double quotes may contain delimiters and line breaks, and a doubled quote stands for one quote character. When writing the new file, only fields that need quotes get them.
Reading and converting run on a background thread, so the page stays responsive even with files of several megabytes. The Excel output uses UTF-8 with a BOM, a comma and Windows line endings. Excel's own habits are outside the file: it still drops leading zeros and may turn long numbers into scientific notation when it opens a CSV, which is controlled by Excel's import settings, not by the encoding.
Frequently asked questions
Is my file uploaded anywhere?
No. The file is read and converted inside your browser, and the tool does not send the file or its contents to a server. Closing the page discards it.
What is a BOM and do I want one?
A BOM (byte order mark) is three bytes at the very start of a UTF-8 file that announce the encoding. Excel for Windows relies on it to open UTF-8 CSV correctly. Many programs, databases and Unix tools prefer files without it, so choose UTF-8 without BOM for those.
The preview still looks wrong after conversion. What now?
Use Read as to choose the encoding yourself and watch the preview change. A file can have been saved wrongly before it reached you, for example Korean text already replaced by question marks, and no tool can bring those characters back.
Excel still removes the zeros at the start of my numbers.
That comes from Excel turning text that looks like a number into a number, not from encoding. In Excel use Data, then From Text/CSV, and set the column type to Text before loading.
How big a file can I convert?
Files of several megabytes convert in about a second. Very large files depend on your device's memory because the whole file is held in memory while it is read and converted.