Format Converter
Lossless conversion between XLSX, XLS, CSV, and TSV formats
Upload File to Convert
Supports .xlsx, .xls, .csv, .tsv formats
Supported: .xlsx, .xls, .csv, .tsv
Format Converter
Lossless conversion between XLSX, XLS, CSV, and TSV formats
- Supported: .xlsx, .xls, .csv, .tsv
- Local processing with privacy by design
- Millions of rows, instant
- Keep formulas & formats
Common use cases
Format mismatch is the most common blocker when importing data into another system
Hand off CSV to accounting systems
Many ERPs accept CSV but not XLSX. Convert in one click, with proper UTF-8 encoding so accent marks and CJK characters survive.
Prepare TSV for database import
PostgreSQL COPY, MySQL LOAD DATA, and BigQuery prefer TSV. Convert your XLSX exports to import-ready TSV instantly.
Convert legacy XLS to modern XLSX
Some HR systems still emit .xls. Convert to .xlsx in your browser — no need to open Office or run a server-side macro.
Best practices
Pick the right target
Use CSV for maximum compatibility (single sheet, comma-separated). Use TSV for database imports. Use XLSX to preserve multi-sheet structure.
Data security
Conversion happens in your browser. Source and output files never leave your device — ideal for sensitive payroll or PII data.
Performance
For very large files (100k+ rows), expect a few seconds. The browser may show a spinner — that's SheetJS working, not a hang.
Round-trip verification
When in doubt, convert back to the original format and diff the two files using the Compare tool — they should match cell-for-cell.
Frequently Asked Questions
Which formats can I convert between?
XLSX, XLS, CSV, and TSV in any direction. Pick your source on upload and target format on the second step.
Will multi-sheet workbooks survive a CSV export?
CSV is single-sheet by design. When converting XLSX → CSV with multiple sheets, choose which sheet to export — the others are skipped.
How are special characters and encoding handled?
Output is UTF-8 with BOM for CSV/TSV, ensuring Excel opens Chinese, Japanese, Korean, and European accents correctly without manual encoding.
Are formulas converted or evaluated?
Formulas are evaluated to their displayed values during conversion to CSV/TSV (since those formats don't support formulas). XLSX → XLSX is lossless.