Spreadsheet Converter: XLSX, CSV, ODS, TSV, JSON and HTML, One Sheet at a Time
Every spreadsheet eventually has to leave the program it was made in. A supplier wants CSV, a developer wants JSON, a LibreOffice user wants ODS. A spreadsheet converter handles all of that, but nobody explains what happens to a workbook with five tabs when the output format can only hold one. This guide is built around that question: how to convert xlsx to csv from the exact sheet you mean, what an excel to csv converter throws away, and why your dates might turn into five-digit numbers.
1. Which Sheet Ends Up in the File
A workbook is a folder of tables. CSV, TSV, JSON and HTML are not: each is one flat table, so converting to any of them means something has to decide which tab survives. Excel decides silently, writing whichever sheet was active when you hit Save As. That is the whole story behind excel to csv only saves first sheet and csv lost all my other tabs: the other tabs were never lost, they were never written.
This tool makes the decision visible. With more than one sheet, a Sheet dropdown appears and the live preview redraws to show the tab you picked. To export one sheet from excel workbook to csv, or to convert second sheet of xlsx to csv online, choose it, check the preview and convert. For the other tabs, change the dropdown and convert again; the file stays loaded.
XLSX and ODS can hold many sheets, so they offer a second choice. By default only the selected sheet is written, into a fresh single-tab workbook, the quickest way to split multi sheet excel into single sheet xlsx. Tick Export All Sheets and the whole workbook is written instead.
2. How to Use the Free Online Spreadsheet Converter (Step-by-Step)
It is an excel to csv converter no signup required, no email step, no watermark. Three steps cover every direction, so this is how to convert xlsx to csv and every other pairing:
Drop in your spreadsheet
XLSX, XLS, CSV, TSV and ODS are accepted. The tool reports the size and sheet count and previews the first sheet.
Pick the sheet and the format
Choose CSV, Excel, JSON, OpenDocument, TSV or HTML table. With several tabs, pick one from the Sheet menu and the preview follows.
Convert and download
Press Convert & Download. The file arrives named after your original with the new extension. Change the format or sheet and press again.
No size cap is written into the tool, which matters if another converter has turned a large export away. It is an xlsx to csv converter no file size limit in the plain sense; a large export simply takes longer to read. Press New to load the next file.
3. The Six Output Formats and When to Pick Each
Four of the six are flat single-sheet text formats; two are full workbooks.
CSV (.csv)
The universal import format. Cell text arrives as it displays in the source, so a date shown as 12/03/2024 stays 12/03/2024.
TSV (.tsv)
CSV with tabs instead of commas. Convert excel to tsv when your values contain commas and the receiving tool splits them wrongly.
JSON (.json)
An array of objects, one per row, keyed by the header row. The shape a developer wants for a fixture file. Section 4 has the details.
HTML Table (.html)
An unstyled page holding one table. Convert excel sheet to html table when the rows need to go into an email, a CMS or a docs page.
Excel (.xlsx)
A modern workbook. The output for xls to xlsx and csv to xlsx, and the tsv to xlsx converter online route for tab-delimited exports.
OpenDocument (.ods)
The native LibreOffice format. A csv to ods converter online for a Linux desk, or for a portal that specifies ODS.
A word on CSV, the format that causes the most arguments. There is a specification, IETF RFC 4180, but almost every program bends it. The CSV and TSV written here use a plain line feed between rows and no byte-order mark, which is what import scripts expect. Excel on Windows sometimes misreads accented characters in such a file; if so, open it through Excel’s Data import and choose UTF-8. Input and output are independent, so the ods to csv converter free online direction works like every other pairing.
4. Excel to JSON: An Array of Objects, and the Date Problem
If “need excel data as json for my app” brought you here, the JSON output is built the way most code expects. The first row of the selected sheet becomes the property names, every row below becomes one object, and the file is one array of those objects, valid against ECMA-404. That is the meaning of convert excel to json array of objects, and this xlsx to json converter online free produces it with nothing to configure.
Numbers stay numbers and a TRUE cell is a boolean. An empty cell becomes null so every object has the same keys, and blank rows are dropped. A blank header becomes __EMPTY and a duplicate gets a _1 suffix, so tidy the header row first.
Excel dates showing as numbers in JSON
Excel stores a date as a serial number counting days from the end of 1899 and formats it as a date only for display. CSV and TSV carry the displayed text, so dates look like dates there. JSON carries the raw value, so a date cell arrives as its serial: 45123 is 16 July 2023. The tool does not translate this, and it is better to know now than in production. The fix is one line: add the serial as days to 30 December 1899. Or format the column as text before converting and the string comes through. Afterwards, our JSON formatter validates the file.
5. Old XLS Files, ODS and Moving Between Office Suites
Often the problem is not the file but the program. Three situations recur.
Old XLS file won’t open in Excel
Excel 97-2003 files use a binary layout that current versions treat with suspicion, and some corporate policies refuse them. The answer to how to convert xls to xlsx without excel is to load the .xls here and choose Excel (.xlsx). One honest limit: the tool reads legacy XLS but does not write it, so xlsx to xls is not on the menu. For someone on a very old Excel, send CSV instead.
Excel file won’t open in LibreOffice
The cause is usually something Excel-specific bolted onto the workbook. To convert xlsx to ods, choose OpenDocument, tick Export All Sheets if you want every tab, and download. ODS is standardised as ISO/IEC 26300, and LibreOffice opens its own format without the guesswork it applies to XLSX. To convert ods to xlsx online for a colleague on Office, flip the dropdown.
Convert XLSX to CSV on a Mac without Excel
Excel is not on every Mac. To convert xlsx to csv on mac without excel and get exactly the sheet you asked for, load the workbook here, pick the tab from the Sheet dropdown and choose CSV; the same route gives you TSV or JSON, which a spreadsheet program may not offer at all.
6. What Does Not Survive the Conversion
A converter that claims to carry everything across is not telling the truth. This tool moves cell values, plus formula text for XLSX output. It does not move the following, on any output:
- Cell styling. Fonts, colours, fills, borders, column widths and conditional formatting are dropped. The values are right; the paint is gone.
- Charts, images and pivot tables. These sit on top of a sheet rather than inside its cells.
- Macros, data validation, comments and hyperlinks. None of these travel with the cell data, so a macro-driven workbook comes out as plain values.
- Password-protected workbooks. An encrypted file cannot be read. Remove the password in the original program first.
Two scope limits. It takes one file at a time; drop several and the first is loaded. And it does not read or write PDF; if your table is trapped in one, start with PDF to Excel or the wider PDF to spreadsheet suite, then bring the result here. If you end up with one CSV per sheet, the archive creator bundles them into a single zip.
7. Why Cortexis Is the Best Free Spreadsheet Converter
One page, every pairing
Five inputs and six outputs on one page, not a page per format pair. Load once, export as often as you like.
You choose the sheet
A Sheet dropdown and a live preview of the exact tab you are exporting, before the download.
Whole workbook or one tab
For XLSX and ODS output, keep every sheet with one checkbox, or write just the selected tab.
No file size limit, no signup
No account, no email, no daily quota and no size cap written into the tool.
Your data stays private
Your spreadsheets are never stored on our servers, never retained after your session, never used for training or analytics.
Honest about what it drops
Values and formulas move; styling, charts and macros do not. We say so here, up front.
It is one of a set of free document and data tools on the same terms; the file converter hub lists them all, and the presentation converter covers slide decks.
8. Frequently Asked Questions (FAQ)
Is this spreadsheet converter really free with no signup?
Yes. No account, no email gate, no trial period, no watermark. It is free every time.
Why does Excel to CSV only save the first sheet?
A CSV can only hold one table, and Excel writes whichever sheet was active when you saved. Nothing was deleted; the other tabs were simply not written. Load the workbook here, pick each tab from the Sheet dropdown and convert.
How do I convert the second sheet of an XLSX to CSV online?
Load the file, choose the second sheet from the Sheet dropdown, and press Convert & Download with CSV selected. The preview shows that sheet before you download.
Why are my Excel dates showing as numbers in the JSON?
Excel stores dates as serial numbers counting days from 30 December 1899, and JSON output keeps the raw value, so 45123 is 16 July 2023. Add the serial as days to that date in your code, or format the column as text before converting. CSV and TSV carry the displayed text instead.
Will my formatting, charts and macros come through?
Cell values come through on every output, and formulas in XLSX output. Fonts, colours, borders, charts, pivot tables, comments and macros do not.
Is there a file size limit, and do you keep my spreadsheet?
No size cap is written into the tool and there is no daily quota. Your files are never stored on our servers, nothing is retained once your session ends, and nothing is used for analytics or training.
Working with the same data elsewhere? The PDF to Excel converter gets a table out of a PDF before you start, the JSON formatter checks the export you just made, and the file renamer tidies a batch of per-sheet CSVs. If you would rather build the app that consumes the JSON than just produce it, our free full-stack web development course starts at the first line of code.