Replacing Excel with OnlyOffice: What Actually Works and What Breaks
If you are reading this you are probably already halfway through the decision. You have an Excel licence renewal in front of you, or a finance team that keeps emailing workbooks around, and someone has suggested OnlyOffice. The question is not which spreadsheet is better in the abstract. It is whether your specific workbooks survive the move.
The honest answer is that most do, some do not, and the ones that break break in ways that are not obvious until month end.
What actually has to survive
"Replacing Excel" means three different projects depending on who you are:
- Personal use. You open files, do some analysis, maybe build a budget. Almost anything free works.
- Team use. Multiple people edit the same workbook, version control matters, and someone has to own the migration.
- Regulated or on-premises work. The data cannot leave your network. This is OnlyOffice's strongest case, because it is the only serious spreadsheet you can run on your own server.
Be clear which one you are. Most failed migrations are personal-scale tools deployed into a team-scale problem.
Where OnlyOffice is genuinely strong
OnlyOffice Spreadsheet is a real spreadsheet application, not a viewer. It handles the standard function library (its own documentation cites 400+ functions), conditional formatting, charts, pivot tables and data validation. It opens XLSX files natively and saves back to XLSX, which matters more than any feature list because it means the file does not have to be converted to something else first.
The two things it does that Excel desktop does not:
Real-time co-editing in the browser. Google Sheets has had this for years and it is the main reason teams leave Excel. OnlyOffice gives you it, and unlike Sheets you can host the whole thing yourself.
On-premises deployment. The full OnlyOffice suite runs as cloud, desktop or on-premises. If your organisation cannot send documents to a third party server, that single fact decides the whole evaluation.
The three things that will break
This is the part that matters, and it is the part that the marketing pages skip.
1. VBA macros. VBA is the deep end of Excel lock-in. Anything built on a VBA macro is a small program, and you should assume it will not run unchanged. Test your most macro-heavy workbook before you move anything else, because if it fails there is nothing to decide.
2. Power Query and external data connections. Anything that pulls from a database, a web API, a SharePoint list or another workbook needs testing individually. These are the features that turn a spreadsheet into a system, and a system is harder to port than a file.
3. Add-ins. If your team relies on an Excel add-in for planning, statistics or accounting, check whether an equivalent exists. Most do not.
The migration test, in order
Do not start with a blank workbook. Start with the worst file you have.
- Pick your most complicated real workbook. Not a sample. The one with the macros, the external links and the merged cells.
- Open it in OnlyOffice and save a copy. Do not overwrite the original.
- Recalculate every formula. Look specifically for
#NAME?,#REF!and#VALUE!errors. Those are the ones that signal a function that did not translate. - Check the pivot tables. Refresh them rather than just looking at the cached values. A pivot that displays correctly but does not refresh is worse than one that fails loudly.
- Print it. Seriously. Print layout and page breaks are where spreadsheet migrations quietly ruin monthly reports.
- Then do the same for your second worst file.
If both survive that, the migration is viable. If either fails in a way you cannot work around, stop, because it will be worse at scale.
OnlyOffice compared with the other free spreadsheets
| Spreadsheet | Functions | Runs on your server | Best for | Main limitation |
|---|---|---|---|---|
| OnlyOffice Spreadsheet | 400+ | Yes | Teams needing on-prem plus co-editing | Macro and add-in gaps |
| LibreOffice Calc | 500+ | Desktop only | Power users who want a desktop app | No real-time collaboration |
| Google Sheets | 400+ | No | Fast collaboration, cloud-first teams | Cloud only, size limits on large data |
| WPS Office Spreadsheets | 100+ | No | Familiar ribbon interface, light use | Smaller function library |
| Zoho Sheet | 350+ | No | Teams already inside Zoho | Ecosystem dependency |
| Apache OpenOffice Calc | 300+ | Desktop only | Legacy compatibility | Slow development |
Two notes on that table. LibreOffice Calc has the largest function library of the free group and the strongest desktop-feel fidelity to Excel, but it has no real-time co-editing, so it solves a different problem. Google Sheets wins on collaboration and loses on data size and on anything that needs to stay inside your network.
What I would tell a finance team
Migrate the reporting layer first, not the model layer.
Your management reports, dashboards and scheduled outputs are usually simpler than your planning models, and they are the highest-visibility part of the workload. If you move those to OnlyOffice and they work, you have proven the concept and bought credibility with the team. Then take on the models, one at a time, with the original still available.
The mistake is migrating everything at once in a quiet week and discovering at month end that a pivot no longer refreshes.
Where to start
If your reason for moving is cost, LibreOffice Calc is the cheapest answer and the most familiar to Excel users. If your reason is collaboration, Google Sheets is the path of least resistance. If your reason is that the data cannot leave your infrastructure, OnlyOffice is the only one of the three that answers the question.
Browse all fourteen options in Microsoft Excel alternatives, or the wider Spreadsheets and Data Analysis category.