CSV tools that stay in your browser
Six things people need to do to a CSV, each of them free and each of them running inside the tab. The file is read off your disk by the browser and never sent anywhere — which is the part most online CSV tools get to skip explaining, because they upload it.
Open a CSV file in your browser
Drop a file in. It opens here, and it stays here.
Open itRun SQL on a CSV file
Real SQL, on your file, without installing a database.
Open itMerge CSV files into one
Several files in, one file out, columns matched by name.
Open itRemove duplicate rows from a CSV
Duplicates on the columns you say identify a row.
Open itCompare two CSV files
Added, removed, changed — matched on a key, not line by line.
Open itConvert a CSV to PDF
A CSV, laid out as a readable table, saved as a PDF.
Open it
What “nothing is uploaded” means here
Your file is opened by the browser and parsed by a database engine running inside the page, so there is no request that carries it anywhere. The engine itself — DuckDB, compiled to WebAssembly — is downloaded from a public CDN the first time you open a file: that is program code arriving, not your data leaving.
Nothing is stored either. There is no account, no database and no recent-files list, so closing the tab is all the clearing up there is. If you want a file to still be there tomorrow, that is what the apps are for.