Free online SLK to XLSX converter

Legacy reporting, accounting, and database exports may produce .slk files, while current Excel workflows and document archives usually require .xlsx. An XLSX copy is easier to edit, share, and retain in modern spreadsheet software.

What SLK files contain

SLK usually refers to SYLK (Symbolic Link), a Microsoft spreadsheet interchange format unrelated to filesystem symbolic links. It is a text-based format whose semicolon-delimited records describe cell coordinates, values, formulas, and limited formatting information.

Older Excel installations and legacy accounting, database, ERP, reporting, and scientific applications may export SYLK files such as report.slk. SYLK is normally used for a single worksheet and represents far fewer workbook features than current Excel formats.

What XLSX adds

XLSX is the default Excel workbook format used by Microsoft Excel 2007 and later. It is an Office Open XML package: a ZIP container holding XML data for worksheets, formulas, styles, workbook settings, and related components.

XLSX can contain multiple worksheets, tables, filters, charts, named ranges, data validation, and modern cell styling. It is supported by Excel and LibreOffice Calc and can be imported by Google Sheets and many business applications. A standard .xlsx workbook cannot contain VBA macros; macro-enabled Excel files use .xlsm.

Convert the file

To convert without installing software, upload the .slk file to 101convert.com, choose XLSX as the output format, start the conversion, and download the resulting workbook. Open the downloaded file in a spreadsheet application and check the data before distributing it.

Microsoft Excel can save a SYLK file directly:

1. Open source.slk in Excel.
2. Check the worksheet layout, cell values, formulas, and text fields.
3. Select File → Save As.
4. Choose Excel Workbook (*.xlsx), enter a filename such as source.xlsx, and save.

LibreOffice Calc is a desktop alternative. Open the file, select File → Save As, choose Excel 2007–365 (.xlsx), and confirm Use Excel 2007–365 Format if prompted.

For batch conversion with LibreOffice, create an output directory and run:

libreoffice --headless --convert-to xlsx:"Calc MS Excel 2007 XML" --outdir output input.slk

Check conversion results

Conversion can retain only data and formatting represented in the source SYLK file. It cannot recreate absent worksheets, charts, images, pivot tables, macros, conditional formatting, or complex workbook settings.

Verify formulas, especially those using external workbook references, obsolete functions, or locale-specific decimal and list separators. Excel and LibreOffice can calculate some formulas differently, and an XLSX file may display cached formula results until recalculated.

Inspect dates and identifiers after conversion. An exporter may write dates as text rather than spreadsheet dates, and numeric-looking account numbers, postal codes, and long IDs can lose leading zeroes or display in scientific notation. If characters have already been converted to numbers, recover the original value from the source export and store the column as Text.