MESCIUS
Rutba Office vs SpreadJS
A commercial JavaScript spreadsheet component, licensed per developer, with a companion visual Designer. It imports and exports .xlsx and is embedded in the host application’s own interface.
Ours is the free one, so read this knowing whose page you are on. What follows starts with where SpreadJS beats us, because on this page that is the part you cannot get from them.
First, honestly
Where SpreadJS wins
Not a courtesy paragraph. Each of these is a real reason to choose them over us.
Spreadsheet depth we are years from
Hundreds of functions, pivot tables, charts, conditional formatting, data validation, sparklines, a formula editor. If your product needs a spreadsheet that behaves like Excel to a demanding user, this is what that looks like.
A Designer, and a support contract
A visual designer for building sheets and templates, plus commercial support with somebody to escalate to. Neither exists here at any price.
Browser-native, and built for it
Designed to render and recalculate in the browser at scale. Ours is a Node engine that sends a view model to a window — a different architecture, and theirs is the right one for a web application.
And ours
Where Rutba Office wins
Free, and the source is published
Per-developer commercial licensing against the AGPL. For a project that can live with copyleft, that is the difference between a line in a budget and no line at all.
It runs where there is no browser
The engine works in Node, in buffers, with no DOM — so a server can open, recalculate and save a workbook inside a job, which is a different task from rendering a grid to a person.
Documents and slides from the same codebase
A spreadsheet component is a spreadsheet component. Ours ships beside a .docx engine, a .pptx renderer, a PDF writer and a mail library that reads .pst — one dependency and one licence conversation for all of it.
Side by side
The seven structural questions
Asked of editors and engines you build with. A component and a desktop suite are not decided on the same seven, so each group has its own.
| Question | Rutba Office | SpreadJS |
|---|---|---|
| Free in productionUsable in a shipping product at no cost | Yes | No |
| Source publishedYou can read and change the code | Yes | No |
| Microsoft formatsReads and writes .docx, .xlsx or .pptx as such | Yes | Yes |
| Runs server-sideWorks in Node with no browser and no DOM | Yes | Partly |
| Preserves what it does not understandA round trip returns untouched parts byte-for-byte | Yes | No |
| Closed-source embeddingA licence exists that permits it without publishing your source | Partly | Yes |
| A whole suite above itDocuments, sheets, slides and mail from the same codebase | Yes | No |
These seven are the questions this project was built to answer, so of course it answers them. Feature depth, maturity, collaboration and support contracts are not on this table, and SpreadJS beats us on at least one of those.
Verdict
Who should choose which
If you are embedding a spreadsheet in a commercial web application and it must satisfy people who use Excel all day, buy theirs: the depth is not close and the support is real. Take ours if you need the engine server-side, if the whole document family matters rather than sheets alone, or if a per-developer licence is the thing standing in your way.
Model-level descriptions from MESCIUS’s published licensing and product structure, as of 8 September 2026. No prices are reproduced here — check developer.mescius.com/spreadjs for those.
It costs nothing to find out
Install it beside whatever you use now — a normal per-user install, a normal uninstall.