Browser tools
Confirm the file is an unencrypted `.xlsx` workbook within the 128 MiB limit, then try the sample. All browser editor, extraction, conversion, and comparison work stays on the device.
Desktop Excel Editor
The desktop and browser XLSX editors share the same local workbook SDK. Source saves retain existing formulas, styles and unrelated package parts. Imported formula results are retained until a cell edit; supported formulas then recalculate locally. Calculation coverage is partial; unsafe or unsupported changes report an explanation. Check the saved output before replacing your only copy.
XLSX Editor in ChatGPT
Use the installed XLSX Editor by Loamstack extension and open the workbook through its XLSX file handler. Choose an unencrypted .xlsx file up to 20 MiB. A normal file preview or a similarly named native editor is a different workflow.
If the editor cannot read the selected file, check whether your host supports extension file access. Save requires host write permission and a current file version. A read-only file or missing version cannot be overwritten. If another editor changes the file, retain your unsaved work and resolve the conflict before reloading. Formula calculation has partial coverage; an unsupported result is not a successful formula check.
For help, use the form below and include your host and extension versions, the action that failed and a safe error description. Use a fictional example; do not send credentials or private workbook contents.
XLSX Formula Checker MCP
Check the endpoint and release status on the MCP setup page. No account is needed for the formula MCP. Supply a small example directly in the tool call; it cannot see files merely opened in the browser or desktop app. Check any reported limits or unsupported functions. Optional AI help may be unavailable without affecting deterministic checks.