A1
empty sheet

## Edit an Excel spreadsheet without Excel

Open an .xlsx, change the cells, save it back as a real .xlsx that opens cleanly in Excel, LibreOffice, Google Sheets, and Numbers. Values, formulas, multiple sheets, dates, and column widths all survive the trip. CSV files open and save too, with the delimiter auto-detected.

## Formulas that actually work

Start a cell with `=` and write it like you would in Excel: `=SUM(B2:B9)`, `=IF(C2>100,"over","under")`, cell math like `=A1*1.21`, references across sheets like `=Sheet2!D4`. The engine is hand-written and covers the everyday set — SUM, AVERAGE, MIN, MAX, COUNT, COUNTA, COUNTIF, SUMIF, IF, AND, OR, NOT, IFERROR, ROUND, ROUNDUP, ROUNDDOWN, INT, ABS, SQRT, POWER, MOD, LEN, LEFT, RIGHT, MID, UPPER, LOWER, TRIM, CONCAT — plus `&` for joining text. Inserting and deleting rows or columns rewrites your formula references the way Excel would.

## The ledger contract

This is deliberately a quick-edits editor, not an Office replacement. Open a heavily-produced workbook — charts, pivot tables, cell colors, merged cells, macros, exotic formulas — and those parts are simplified down to this editor's vocabulary when you save: your values and everyday formulas, on clean sheets. For fixing a price list or balancing a small ledger, that's exactly what you want; for the quarterly model with 40 tabs of pivots, use the real thing. The editor autosaves your work-in-progress to your own browser as you type.

## Honest limitations

- Saved workbooks keep: cell values, everyday formulas, multiple sheets, dates (as real Excel dates), and column widths. Formatting — colors, fonts, borders, merged cells — plus charts, pivot tables, comments, and macros are dropped on save.
- Formulas the engine doesn't know (VLOOKUP, array formulas, …) show `#NAME?` here but the formula text itself is preserved and saved back intact — Excel recalculates them on open.
- Old binary .xls files (pre-2007) aren't supported — save as .xlsx first, or open them in LibreOffice.
- Dates are shown as `YYYY-MM-DD`; type them that way and they save as true Excel dates.
- Autosave lives in this browser on this device. Download your file when it matters.

Same shelf: Draft Desk edits Word documents the same way · File Mill converts CSV/JSON/XLSX and ~25 other formats · Proof Desk shows exactly what changed between two files.

Part of K-Engine Local Tools — free, privacy-respecting utilities that run on your device. The ZIP and XLSX readers and writers are hand-written; view-source on this page and you're reading all of it. MIT licensed, from the K-Engine workshop · download the source.