Can I open an .xlsm file without Microsoft Excel?

Yes. Any spreadsheet program reads the sheets. The question is what survives: the VBA project, the Power Query definitions, the formulas the engine does not know, the cached values your macros computed. Check the file first, then open it in a tool that keeps those parts.

Do the macros still run without Excel?

Some do. SumSheet runs macros it can route natively in its own sandbox; on the public Enron corpus that is 73 % of the 13 870 macros a person can start. 18 % wait for work on our queue, 8 % stay in Excel by design. Your file gets its own numbers from Check my Excel file, in seconds, without running anything.

Will Excel open the file again after I edit it elsewhere?

With SumSheet, yes, measured: a macro workbook edited and saved back came out with 14 parts of 14, vbaProject.bin byte-identical, 197 formulas of 197, defined names kept, and Excel opened it without a repair dialog.

Checking a file, opening it in the browser, the desktop apps for evaluation, the Docker images and the MCP server are free, with no account. Files uploaded to our server are deleted after 24 hours. Production inside an organization is licensed per application.

=OPEN(report.xlsm) without Excel

A straight answer

Open an .xlsm without Excel: what survives, what doesn't

Any spreadsheet program will show you the sheets. That is not the question. The question is whether the file still works afterwards: the macros, the Power Query steps, the formulas, the values your VBA functions computed, and whether Excel opens the result without a repair dialog when a colleague gets it back. This page says what is inside an .xlsm, what a tool has to keep, what SumOffice keeps (measured, not promised), and three free ways to open yours today.

What is actually inside an .xlsm

An .xlsm is a ZIP package. Beyond the worksheets it carries parts that a plain importer never looks at, and those parts are exactly what makes the workbook yours:

Worksheets	Cells with formulas and the last computed value of every formula. A tool that recomputes everything and does not know a function replaces your number with an error.
VBA project	`xl/vbaProject.bin`: modules, procedures, events like `Worksheet_Change`, UserForms, references. Some tools drop it on save; some keep the bytes but cannot run a line.
Power Query	The queries live in a compressed part (`DataMashup`) with the M steps, connections and load targets. Most non-Excel tools do not model it at all, so it is silently gone after the first save.
Defined names, tables, pivots, charts, validations, conditional formats, external links	Each is a separate part or a separate XML element. Each is a separate way to lose something.

The practical rule: a tool keeps what it models. Anything it does not model is dropped on the first save, usually without a warning. That is why "it opened fine" tells you nothing; "it saved and Excel opened it clean" does.

What SumOffice keeps, measured

The VBA project, byte for byte. A macro workbook from the public Enron corpus (2 sheets, 861 cells, 197 formulas, VBA): opened in SumSheet, edited, saved back. The saved file: 14 parts of 14, vbaProject.bin identical to the original, 197 formulas of 197, defined names kept. Excel opened it without a word.
Macros that run. Of the 13 870 macros a person can start in the 3 738 Enron macro workbooks, 73 % route native (SumSheet can attempt them in its own sandbox), 18 % wait for work on our queue, 8 % stay in Excel by design. Read, not run: the numbers come from the source, and your file gets its own.
Cached values of functions the engine does not know. A user-defined function computed in Excel keeps its last value instead of turning into #NAME?. This was a defect we found and fixed on 20 September 2026 while testing exactly this page's claim; we say so because the alternative is pretending.
Power Query definitions. Queries travel with the file untouched and refresh in the desktop SumSheet; in the browser and in Nextcloud they are preserved, not refreshed.
Speed. A workbook with 400 000 formulas opens in about 0.1 s; recalculation on open of the Enron workbook above took 126 ms.

What does not survive yet, honestly

Macros that route "Excel bridge" (COM automation of other applications, some UserForm and ActiveX logic) stay in Excel. The report names each one.
Power Query does not refresh in the browser editor or inside Nextcloud today, only in the desktop app.
One editor per document at a time in the browser; a second person gets it read-only.
Functions the engine does not know keep their cached value but are not recomputed. The report lists them by name.

Three free ways to open your .xlsm today

1. Check, then open	Check my Excel file: drop the workbook, get the report in seconds (macros with routes, functions known N of M, Power Query, data sources), then press Open it and the same file opens in the real engine in your browser. Nothing is executed during the check; the file is deleted after 24 hours. The same report comes from the Slack and Telegram bot.
2. Inside your Nextcloud	Two Docker images and the standard Nextcloud Office app: click the .xlsm in Files, edit, save back, download, open in Excel. Three steps, measured: Excel and Word in Nextcloud.
3. From an AI agent	An MCP server opens your file, reads formulas, macros and queries, proposes an edit, applies it after your approval and returns the file intact, .xlsm in and .xlsm out: MCP server for agents.

For daily work, the SumSheet app runs the macros on your own machine (Windows, macOS, Linux, Android, iOS), and the editors as a server put the same engine on your infrastructure.

How to test any tool with your own file

Take a workbook that matters, with macros and at least one query. Not a demo file.
Open it in the tool, change one cell, save under a new name.
Open the saved copy in Excel. A repair dialog means parts were dropped or rewritten.
Press Alt+F11: is the VBA project there, with all modules? Open Data, Queries and Connections: are the queries there?
Run one macro. Compare one computed value with the original.

That is the test we ran on our own engine before writing the numbers above. If your file fails any step in SumOffice, tell us which one; that is how the next fix gets found.

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