Convert Excel to TOML Online

Paste an Excel table below, edit it if you need to, and get TOML back. The conversion runs in your browser, so nothing is uploaded, there is no size limit and there is no signup.

From

From a page

The only part of this site that uses a server. The address is sent to it so the page can be fetched, because a browser is not allowed to fetch someone else's page itself. Your own files are never involved.

Nothing here is uploaded. The parsing happens on this page.

Edit

Paste or upload something above and it will appear here.

ToDataMarkupDocumentsCodeSchemasImages

Header rowDetect numbers

The output will appear here once there is a table to convert.

What Excel is

An Excel workbook is a zip archive of XML parts describing sheets, cells, formulas, styles and charts. The .xlsx extension is that format; .xls is the older binary one from before 2007.

Finance, operations and anyone who received a file from finance or operations.

What TOML is

TOML is a configuration format with explicit types and a table syntax, designed to be unambiguous where YAML is clever.

Rust and Python projects, and anything with a pyproject.toml or Cargo.toml.

What changes when you convert Excel to TOML

Only the first sheet is read, and cells are read as the text Excel displays rather than the number underneath. That matters for dates: a cell showing 15/03/2026 arrives as that string, not as a serial number you would then have to decode.

Each row becomes an entry in an array of tables. Keys are sanitised to bare keys where possible and quoted where not.

What carries over from Excel to TOML

Excel records 3 things about a table that TOML has no way to hold.

An empty cell and a missing one are the same thing in TOML, so a null and an empty string in the Excel both come out blank and can no longer be told apart.

TOML has no header row. The column names are repeated as keys on every record instead, which is why the result is bigger on disk than the table it came from.

Anything visual in the Excel - weight, alignment, colour, column widths - has no counterpart in TOML and is dropped. The values are what survives.

Both formats record types, so numbers, booleans and nulls survive as themselves rather than as text.

A worked example

Three rows of staff data, with an identifier that has a leading zero, a value containing a comma, a value containing quotes and one blank cell. Those are the four places formats disagree, so they are the four places to look.

Excel in

id,name,role,started,hours
007,Halima Yusuf,"Analyst, data",2024-03-15,38.5
012,"Jonah ""Jo"" Pryce",Engineer,2025-11-02,
104,Wei Chen,Manager,2023-06-30,40

TOML out

[[staff]]
id = "007"
name = "Halima Yusuf"
role = "Analyst, data"
started = "2024-03-15"
hours = "38.5"

[[staff]]
id = "012"
name = "Jonah \"Jo\" Pryce"
role = "Engineer"
started = "2025-11-02"
hours = ""

[[staff]]
id = "104"
name = "Wei Chen"
role = "Manager"
started = "2023-06-30"
hours = "40"

Questions

How do I convert Excel to TOML?

Paste your Excel into the box above or drop the file onto it. Check the table in the grid, then copy or download the TOML from the output panel. It takes one step and the data never leaves your browser.

Does converting to Excel keep my formulas?

No. A table has values, not formulas. If your source came from Excel in the first place, the formulas were already resolved to their results before they reached this page. Anything that was =SUM(A1:A10) arrives as the number it produced.

Is there a limit on file size?

No. The work happens on your own machine, so the limit is your machine's memory rather than an upload cap. A file with tens of thousands of rows converts in a second or two.

Is my data uploaded anywhere?

No. The parsing and generating are done by JavaScript running on this page. You can watch the network tab while you convert and see that nothing is sent.