Stop splitting files and fixing formulas.

Clean, merge, compare and calculate large CSV and Excel files. Describe what you need in plain English, then download the result.

What do you need done?

CtrlK

No formulas. No code. No new spreadsheet app to learn.

From messy file to clean table in three steps

Turn a messy Shopify order export into a clean customer report, without wrestling Excel.

Drop in the file Excel chokes on

CSV or Excel, up to 10 files and 350 MB. It opens in your browser, so your raw files stay on your computer.

See what’s wrong before you fix it

TenMil scans the file and lists every problem it finds, with a count, such as 1,284 duplicate rows or 317 blanks. Fix them with one tap, or just say what you want in plain English.

Nothing changes without you seeing it

Every step shows exactly what changed, and undo puts it back. When it looks right, download it.

The spreadsheet jobs you’d rather not do by hand

Clean up a file someone else made

Duplicates, stray spaces, three date formats, and column names like “Unnamed: 4.” Spaces are trimmed as soon as the file opens. Anything that removes rows waits for your OK.

Match up two lists

See who’s in both files and who’s missing from one. Stack monthly exports into one table. Compare two versions to see what was added, removed, or changed.

Get the answer, not just the data

Want to see top 10 customers, sales by region or only last quarter’s orders? Just ask for it in plain English.

Take it back to Excel

Download as CSV or Excel and plug back into your workflow. Your original files are never touched.

Why TenMil instead of Excel for big files

Rows

Excel: 1,048,576 rows per sheet. A bigger CSV gets cut off when it opens

TenMil.ai: Typically millions. The limit is total file size, not a row count, and it's far above Excel's

File size

Excel: No fixed cap in 64-bit Excel, but large workbooks slow down as memory runs out. 32-bit Excel shares 2 GB of memory with the file, and Excel for the web won't open SharePoint workbooks over 100 MB

TenMil.ai: Up to 10 files, 350 MB combined

Performance

Excel: Built for a grid you scroll and edit, so filters, lookups, and recalculation bog down on hundreds of thousands of rows

TenMil.ai: Runs on real database technology that handles filters, totals, and joins on large spreadsheets many times faster

How you work

Excel: Write formulas, build pivots, set up Power Query, or record VBA macros

TenMil.ai: Say what you want in plain English. TenMil does it and shows what changed

Determinism

Excel: Formulas repeat reliably but break when a column moves or new rows fall outside the range. AI assistants that read the sheet and write the answer themselves can give a different result each time you ask

TenMil.ai: The AI plans the step and standard SQL does the work, so the same actions give the same results, every time

AI usage

Excel: Depends on the add-in or assistant. It can get expensive, and most AI tools can only read part of a large file

TenMil.ai: Light. The AI works from summaries and samples, so a request stays small and costs stay down

Multiple files

Excel: VLOOKUP, XLOOKUP, or Power Query setups that get complicated fast

TenMil.ai: Full multi-file support. Join, stack, or compare versions, with matched and unmatched counts

Capability	Excel	TenMil.ai
Rows	1,048,576 rows per sheet. A bigger CSV gets cut off when it opens	Typically millions. The limit is total file size, not a row count, and it's far above Excel's
File size	No fixed cap in 64-bit Excel, but large workbooks slow down as memory runs out. 32-bit Excel shares 2 GB of memory with the file, and Excel for the web won't open SharePoint workbooks over 100 MB	Up to 10 files, 350 MB combined
Performance	Built for a grid you scroll and edit, so filters, lookups, and recalculation bog down on hundreds of thousands of rows	Runs on real database technology that handles filters, totals, and joins on large spreadsheets many times faster
How you work	Write formulas, build pivots, set up Power Query, or record VBA macros	Say what you want in plain English. TenMil does it and shows what changed
Determinism	Formulas repeat reliably but break when a column moves or new rows fall outside the range. AI assistants that read the sheet and write the answer themselves can give a different result each time you ask	The AI plans the step and standard SQL does the work, so the same actions give the same results, every time
AI usage	Depends on the add-in or assistant. It can get expensive, and most AI tools can only read part of a large file	Light. The AI works from summaries and samples, so a request stays small and costs stay down
Multiple files	VLOOKUP, XLOOKUP, or Power Query setups that get complicated fast	Full multi-file support. Join, stack, or compare versions, with matched and unmatched counts

Built for absolute trust and reliability.

Your files stay in the browser

Not stored on our servers.

Opening, cleaning, merging, and downloading all run in this tab. To plan a step, the AI gets column names, summaries, and a small set of sample values over an encrypted connection, never the whole file. Close the tab and that copy is gone.

Same steps, same results, every time

The AI plans it. SQL runs it.

Many AI tools read your data and write the answer themselves, so ask twice and you can get two different numbers, with no way to check the work. TenMil splits the job. The AI only decides the step, like removing duplicate rows by email, and standard SQL carries it out on every row. Run the same steps on the same file and you get the same table, down to the last row. If a request could mean two things, TenMil asks first, and Undo always puts the previous table back.

Frequently Asked Questions

What does TenMil do?

TenMil opens CSV and Excel files that are too big or too messy for Excel, typically millions of rows, right in your browser. It spots problems as the file opens, like duplicate rows, mixed date formats, and the same name spelled different ways, and fixes them when you say so. You can join or stack files, compare two versions, and filter, sort, or total by group just by typing what you want. Every step shows what changed and can be undone, and you download the result as CSV or Excel.

Do my files leave my computer?

No. Your files are opened and processed in your browser, not on our servers. To plan a step, the AI gets column names, summaries, and a small set of sample values over an encrypted connection, never the whole file. Close the tab and that copy is gone.

How big a file can I open?

Up to 10 files, 350 MB combined. How many rows that holds depends on the file, such as how many columns it has and how much is in each row, but it is typically millions.

Will TenMil change my data before I agree?

A few small fixes happen automatically when a file opens, like trimming extra spaces, and you can undo them in one click. Fixes that drop or merge rows wait for your approval. If a request is unclear, TenMil asks a question first and changes nothing.

Can I undo a step?

Yes. Undo puts the previous table back. Closing the tab discards the in-browser copy, and the files on your computer are never edited.

Do I need an account?

No. You can open a file and run steps without an account. The first download asks for your email. Free use includes 3 downloads a day; see Pricing for the details.

How is this different from Excel?

Excel is great for building and editing a workbook, but it stops at 1,048,576 rows and slows down well before that. TenMil handles the heavy lifting: opening files with millions of rows, cleaning them, joining or comparing them, and cutting them down to what you need. You type what you want instead of writing formulas or setting up Power Query, and standard SQL does the work, so the same steps give the same result every time. Many people then download the result and keep working in Excel.