Formatting preserved
Number formats, conditional formatting, merged cells, column widths and print areas render as laid out — not as a bare HTML table that lost the point of the design.
Excel
Spreadsheets your users can read but not mine
A workbook is rarely just what is on screen. It carries hidden sheets, filtered rows, comments, defined names and whatever somebody parked in column BX. Rendering server-side means the reader sees the report and not the archaeology underneath it.
- 8
- spreadsheet extensions supported
- 0
- Excel installs required
- 0
- hidden sheets shipped to the browser
The problem
The workbook you send is not the workbook you meant to send
Spreadsheets are the format most likely to leak something. Hidden sheets holding source data, filtered rows that unfilter, a pivot cache containing the full table, comments from a negotiation nobody meant to publish.
Converting to PDF first solves the leak and creates a chore: someone has to run the conversion, and the PDF is stale the moment the workbook changes.
Rendering the live workbook server-side gets both. The reader sees current data, formatted as the author intended, and receives an image rather than a file with a basement.
Capabilities
What the viewer does with a workbook
Charts and embedded images
Charts render alongside their data rather than disappearing, which is usually the first thing that breaks in a naive conversion.
The whole family
.xls, .xlsx, .xlsm, .xlsb, .xltx, .xltm, .ods and .csv, all through the same open call.
Paginated like a printout
Output follows the workbook's page setup, so a report designed to print on four pages reads as four pages instead of one endless scroll.
Searchable text
With the AdvancedSearch plugin, cell text is searchable across the rendered document.
No formula engine in the browser
Evaluation happens server-side. The client never receives formulas, defined names or the dependency graph that would let someone reconstruct your model.
Integration
Opening a workbook
Because the viewer is driven by page setup, a workbook with sensible print areas renders far better than one that has never been printed. It is worth checking that before blaming the renderer.
Supported extensions
.xls.xlsx.xlsm.xlsb.xltx.xltm.ods.csv
csharp
// Same call, different family
string token = await viewer.OpenDocumentAsync("wwwroot/files/Q3-Report.xlsx");
// CSV goes through the same path — useful for data exports
// that users want to read rather than download
string csvToken = await viewer.OpenDocumentAsync("wwwroot/exports/ledger.csv");Details
Spreadsheet specifics
- Rendering follows the workbook's page setup — print areas and scaling matter to the result.
- No Excel installation and no interop are involved.
- Text search across cells requires the AdvancedSearch plugin.
Frequently asked questions
Are formulas recalculated?
Rendering reflects the workbook's stored values and formatting. What the client receives is an image of the sheet, never the formulas or the dependency graph behind it.
What happens to hidden sheets and filtered rows?
They are not part of what gets rendered to the reader, which is the main reason teams prefer this to emailing the file. The workbook keeps its structure on your server; the browser gets pages.
Can it handle a very wide sheet?
Yes, though the result follows the page setup. A sheet that has never had a print area defined will paginate awkwardly for the same reason it prints awkwardly.
Related solutions
Word
Word documents without Word on the server
Native DOC/DOCX/RTF/ODT rendering with no Office install, no COM interop and no server-side automation.
WordA PDF viewer that does not hand over the PDF
Server-side PDF rendering into page images — the user reads the document without ever receiving the file.
PDFTry it against your own documents
A temporary licence takes a few minutes to request and runs entirely on your own machine. The files that matter are the ones already breaking your current viewer.