Step 1 / source
Choose the source
Drop one file here
Choose a CSV with one header row and consistently separated columns.
Checking publication status...LOCAL DATA CONVERTER / CSV TO XLSX
CSV to Excel
Turn a header-based CSV into a real XLSX workbook with a styled header, frozen first row, filter controls, and sensible column widths.
Processed in this browserOne UTF-8 .csv file up to 5 MB, with at most 100,000 data rows and 1,000 columns.
CSV - 5 MB
No file upload
This operation runs with browser APIs. Nirmion receives catalogue requests, not the selected source bytes.
Original stays unchanged
The converter creates a separately named output. It never writes back into the source file.
Bounded work
One UTF-8 .csv file up to 5 MB, with at most 100,000 data rows and 1,000 columns.
Plain-language method
How rows become workbook cells
Nirmion parses quoted delimiters, quotes, and embedded line breaks, then writes each value as text into a new worksheet. It adds navigation styling but does not guess data types or formulas.
- 01Choose a valid source
The first row must contain column names. Every later row needs the same number of cells.
- 02Review the conversion choices
Choose the real delimiter. Give the worksheet a short name; unsupported Excel tab characters are removed automatically.
- 03Inspect the separate result
The download ends in _nirmion_tools_workbook.xlsx. Values remain text so identifiers and leading zeroes are less likely to change.
Useful when
Practical jobs this tool handles
- Open an exported CSV with filters and frozen headers.
- Send tabular data to a colleague who expects XLSX.
- Prepare a reviewable workbook without copying rows manually.
Before converting
Prevent shifted columns
- Open the CSV and identify its actual separator.
- Confirm quoted commas or line breaks are properly closed.
- Review identifier columns and dates in the output workbook.
Know the boundary
No type guessing
The converter does not infer currency, date, percentage, or formula cells. This protects source text but means you may apply Excel formatting after download.
Quick answers
Questions before you convert
The workbook is designed for safe first review.
Does it support quoted commas?
Yes. Quoted delimiters, doubled quotes, and embedded line breaks follow bounded CSV parsing rules.
Will values starting with zero survive?
Cells are written as text, reducing accidental identifier changes such as lost leading zeroes.
Can it combine several CSV files?
Not in this route. Convert one table at a time so the worksheet contract stays clear.