◆ File conversionFREE
CSV⇄XLSXShift-JIS, GB18030, EUC-KR, UTF-8 without a BOM — detected, and yours to confirm · then CSV ⇄ Excel, every cell kept as text.
Converter· Local processing
Drop your .csv here
or pick from your device · your file never leaves your browser

CSV opens garbled in Excel?
Pick the encoding — then convert.

01 · what this tool actually does for you

Open a CSV the wrong way and the text turns to mojibake — Excel guesses the encoding and guesses wrong. This tool detects the encoding, shows you a preview, and lets you confirm or override it before converting to Excel; on the way back it writes UTF-8 (with a BOM by default, so Excel opens it clean). Every cell stays text, so 007 never becomes 7. Runs entirely in your browser — the file is never uploaded.

Files never leave your deviceIn-browser · zero upload · nothing stored
You confirm the encodingAuto-detected, never force-converted on a low-confidence guess
Every cell kept as textLeading zeros, IDs and codes stay intact — 007 stays 007
02 · two formats, one clean round-trip

CSV and Excel each trip over the other

This conversion exists so a plain-text CSV and a spreadsheet each stay readable — without the encoding and type surprises in between.

CSVCSV

A plain-text table: rows of values separated by a comma — or a semicolon (common in European locales) or a tab. It carries no encoding label, so whoever opens it has to guess: a file saved as Shift-JIS, GB18030 or EUC-KR, or as UTF-8 without a BOM, is exactly what shows up garbled in Excel.

ExcelXLSX

The grid translators, reviewers and analysts are comfortable in — filter, sort, bulk-edit. The catch: double-click a .csv and Excel picks the encoding and the delimiter for you, mangles anything non-UTF-8, and re-types values that look numeric — a leading-zero 007 becomes 7, a long ID turns into scientific notation.

What this tool guards is that hand-off: it detects the encoding and delimiter, shows you a preview, and converts only once you've confirmed — so nothing is silently mis-decoded. Going to Excel, every cell is written as text (no type inference, so 007 and long IDs survive). Coming back to CSV it emits UTF-8, with a BOM by default so Excel re-opens it without mojibake — or without one for git and programmatic pipelines. It's a generic table converter: no localization structure is assumed, and real newlines inside cells stay real.

03 · common questions

You're probably wondering

Why does my CSV open garbled in Excel?+
Because a CSV carries no encoding label, and Excel guesses. If the file was saved as Shift-JIS, GB18030, EUC-KR, or as UTF-8 without a BOM, Excel's guess is often wrong and the text turns to mojibake. This tool detects the encoding, shows a preview, and lets you confirm or change it before converting — so the text comes through correctly.
What is a BOM, and should I keep it on?+
A BOM is a few invisible bytes at the start of a file that mark it as UTF-8. Excel relies on it: with a BOM, double-clicking a .csv opens it clean; without one, Excel may fall back to a legacy encoding and garble non-ASCII text. So the default here is UTF-8 with a BOM. Turn it off when the file feeds a git repo or a program that expects raw UTF-8, where a BOM can get in the way.
Does it support Shift-JIS, GB18030 and other legacy encodings?+
Yes — it round-trips UTF-8 (with or without a BOM), UTF-16 LE/BE, Shift-JIS (Japanese), GB18030 (Simplified Chinese) and EUC-KR (Korean). The detector proposes the most likely one; when it can't be sure it stays out of your way and asks you to pick, rather than converting on a bad guess.
Will leading zeros and long IDs survive?+
Yes. Every cell is written to Excel as text, so a product code like 007 stays 007 and a long numeric ID doesn't collapse into scientific notation. There's no type inference — what's in the CSV is what lands in the sheet.
Will my file be uploaded?+
No. Detection and conversion run entirely in your browser (a Web Worker handles large files up to 50 MB); the file never leaves your machine and never touches a server. That is a hard requirement for NDA-bound work, so the tool is built fully client-side.
04 · who made this / why

Built by someone who's hit this wall

This isn’t a thin wrapper over a large model, and it isn’t an open-source library reskinned. It comes from years of game-localization frontline work and the pile of "nobody notices until it breaks" details that come with it.

A CSV has no encoding label; Excel guesses and guesses wrong — fixing the mojibake shouldn't be a human's job to absorb.

Hand a Shift-JIS or no-BOM CSV to someone on Excel and it opens as mojibake, or the leading zeros vanish, or the delimiter is read wrong. We hit every one of those, so the tool guards them by default: the encoding is detected and confirmed, the delimiter is shown, and every cell is kept as text.

Free, fully local, instant. It's one step in a workflow, not a platform — but it comes from a place that genuinely understands the work.