SheetTool is a free online CSV editor for private spreadsheet work.
Open CSV, Excel, or JSON files, clean messy data, convert formats, merge spreadsheets, split large files, and compare changes without sending your data to a server.
SheetTool workspace
Built for quick CSV cleanup, conversion, and review.
Use the tool
One spreadsheet workspace for many CSV jobs
Use the same editor to convert CSV to Excel, clean duplicate rows, merge files, split large spreadsheets, compare changes, and export the result in the format your workflow needs.
One focused toolkit
Everything you need for day-to-day CSV and spreadsheet cleanup
Replace one-off converters and manual spreadsheet chores with a private browser-based workspace for common file tasks.
Edit and transform
Sort, filter, find and replace, apply formulas, and transform full columns without leaving the grid.
Clean messy data
Trim whitespace, remove empty rows, deduplicate records, and scan for inconsistent columns.
Compare spreadsheets
Diff two CSV or Excel files side by side with clear change highlighting.
Merge files
Combine multiple spreadsheets into one clean file while keeping the result editable.
Split large CSVs
Break big files into smaller chunks by row count or column values for easier handoff.
Convert formats
Export between CSV, XLSX, XLS, and JSON when a workflow needs a different format.
Simple workflow
From messy file to ready-to-share spreadsheet
SheetTool keeps import, cleanup, review, and export in one place so you can finish small data jobs quickly.
Open a file
Drag in a CSV, XLSX, XLS, or JSON file, or use sample data to try the editor instantly.
Fix the spreadsheet
Edit cells, clean columns, merge files, compare changes, and apply formulas in one workspace.
Export your result
Download the finished spreadsheet as CSV, Excel, or JSON with no server processing.
Supported formats
Convert between common spreadsheet and data files
Open the file you have, make the changes you need, and export the file your team or system expects.
CSV
Import, edit, clean, split, merge, and export
XLSX
Open Excel workbooks and export clean files
XLS
Support for legacy Excel spreadsheets
JSON
Convert structured JSON to spreadsheet rows
CSV to Excel /Excel to CSV /JSON to CSV /CSV to JSON
Your data stays on your device
This tool is designed for sensitive spreadsheets that should not be uploaded just to make a quick edit or conversion.
Files are parsed locally with client-side JavaScript.
Your spreadsheets are never uploaded to a server.
No account is required before you start editing.
There is no tracking or analytics added to the tool.
FAQ
Questions before you start?
What is SheetTool?
SheetTool is a free online CSV editor and spreadsheet tool for cleaning, editing, converting, merging, splitting, and comparing CSV, Excel, and JSON files.
Can I use SheetTool as a CSV to Excel converter?
Yes. Open your CSV file, clean or edit it if needed, then export it as an XLSX file. The conversion runs in your browser.
Can I merge multiple CSV files?
Yes. Use the Merge tool to add additional CSV or Excel files. The combined rows stay editable before you export.
Is my spreadsheet data private?
Yes. SheetTool processes files locally in your browser, so your spreadsheets are not uploaded to a server.
Which file formats are supported?
CSV, XLSX, XLS, and JSON are supported for importing and exporting common spreadsheet workflows.
Can I edit cells directly?
Yes. Click into the grid to edit cells, then use toolbar actions for sorting, filtering, cleaning, formulas, and export.
Is there a file size limit?
There is no hard server limit because everything runs locally. Performance depends on your browser and device memory.