Loamstack

Open and edit XLSX, CSV, TSV, JSON and Parquet files locally in your Loamstack browser workspace.

Open and edit XLSX, CSV, TSV, JSON and Parquet files locally in your browser. Loamstack opens local data files without an account, payment, telemetry or automatic upload. The table workspace supports CSV, TSV/TAB, JSON, JSONL/NDJSON and Parquet. The separate Workbook workspace provides an Excel-style ribbon, formula bar, sheets and source-preserving XLSX downloads. Choose Open workbook workspace in the toolbar popup, open a local XLSX, select a cell, edit its value, Apply, Undo/Redo and Save a downloaded copy. Your table workspace stays open in its own tab. Original files are never overwritten. Verify downloaded edits before closing unsaved work. XLSX input limit is 50 MB. Supported editing and fidelity limits appear in the Workbook workspace. Table limits are 32 MiB, 100,000 rows, 1,000 columns and one million cells, with additional Parquet decoded-data limits. Unsupported nested JSON and Parquet fields are inspection-only. Optional link import is a separate table feature. Right-click an HTTP(S) file link, review its address and explicitly grant access only to that host. Requests omit cookies and authentication credentials and reject redirects. Local file editing works offline. All executable scripts, WASM and fonts are bundled.