plain text · into excel

CSV to XLSX CSV in. Workbook out.

Excel can open a CSV. But it can't always save it back as a real .xlsx without losing the encoding, the dates, or the leading zeroes on your zip codes. Morph runs SheetJS in your browser tab — the parser keeps the encoding, the formats, the leading zeroes. The CSV stays where it was. The XLSX saves locally. No Office license required. Free for everything that runs on your device; AI is paid in credits.

Open Morph
Drop a file here
CSV → XLSX
Choose a file
Reads and writes inside this tab. Nothing is sent anywhere.

What it actually does

01
READ

CSV parsed cleanly

UTF-8, UTF-16, Latin-1 — the parser detects and preserves. No mojibake on the round-trip.

02
TYPE

Numbers stay numbers

Dates get the date format. Currencies get the currency format. Zip codes keep their leading zeroes.

03
WRITE

Real .xlsx, not .xls

Office Open XML, the spec Excel actually uses. Opens in Excel, Numbers, Sheets, LibreOffice — all of them.

04
BATCH

Folder of CSVs in

Each CSV becomes a sheet in one workbook, or each gets its own .xlsx. Your call.

How it works

  1. Open morph.cool. Browser only — no install, no account.
  2. Drop the CSV — or a whole folder of them.
  3. Pick XLSX from the format menu. SheetJS handles the rest.
  4. The workbook downloads. The CSV stays where it was.
  5. Open in Excel, Numbers, or Sheets. Encoding intact, types preserved.
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∞Batch limit
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Why people leave the upload-and-queue tools

The trip from CSV to XLSX trips up most converters because CSV is type-blind. Every column is a string until something says otherwise. Morph runs heuristics on each column — ISO dates become dates, plain numerics become numbers, leading-zero strings stay strings. Excel opens the file and sees what you'd expect to see. The whole conversion runs in your tab.

Frequently asked

Why not just open the CSV in Excel and Save As?

Two reasons. Encoding (Excel still defaults to Windows-1252 on import on some platforms) and type detection (zip codes, dates, currencies). Morph's converter handles both correctly.

Does this work without Microsoft Office installed?

Yes — Morph writes the .xlsx file format directly via SheetJS. No Office license required.

What about formulas, formatting, multiple sheets?

CSV is single-sheet, value-only by definition. The output XLSX has one sheet, raw values, with type detection applied. For multi-sheet workbooks from multiple CSVs, drop a folder.

Can I batch a folder?

Yes. Either get one workbook per CSV, or one workbook with all CSVs as separate sheets. Your call.

File size limit?

Whatever your browser's RAM allows. Files of several hundred MB work on most modern machines.

Is there a free tier?

Yes. Everything that runs on your device is free with no cap. AI and server work is paid in credits, about a cent each.

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Nothing leaves your device · Free for what you make, credits for what we run