Can I limit the replacement to one column?

Yes. Pick a column and only its values are touched — replacing "St" with "Street" in an address column must not rewrite "St" inside a name two columns over.

Will I see the changes before downloading?

Yes. The preview shows how many cells change and lets you browse exactly which ones, before the download button becomes active. Nothing is replaced sight unseen.

What happens to the values that do not match?

Nothing. Every value you did not touch is carried through exactly as written — leading zeros, long numbers, dates that look like words, quoting and line endings included.

Can I match a pattern rather than exact text?

Yes — turn on pattern matching to match shapes of text rather than one exact string, with a tester that shows what your pattern catches before anything is replaced.

Is find and replace case-sensitive?

Your choice. It ignores capital letters by default, and a switch makes the match exact when "ID" and "id" mean different things in your file.

Is my file uploaded anywhere?

No. When you find and replace in a CSV here, the work happens inside this page and the browser is told to block outbound connections, so there is no upload to intercept. Watch the Network tab of your developer tools while you find and replace in a CSV: the only requests are for this site’s own code, and none carries your file.

Find and replace in a CSV

Replace text across the whole file or one column, exact or by pattern, with a preview of every change before you download.

Find and replace in a CSVRunning on your device

Source

Your file

or drag one here · it stays on your device

Result

Add a file. Nothing is replaced until you have seen exactly what would change.

How this works

Add your file. Drop a CSV onto the page.
Say what changes. Type the text to find and its replacement, and pick a column if only one should change.
Check and download. Browse the affected cells, then save the result.

What it cannot do

One find-and-replace at a time; a sequence of replacements is what saved recipes are for.
Pattern matching follows one common convention; a pattern written for another dialect may need small adjustments, and the tester shows you immediately.
Replacement works on values, not on column headings; renaming columns belongs to the editor.

Questions

Can I limit the replacement to one column?: Yes. Pick a column and only its values are touched — replacing "St" with "Street" in an address column must not rewrite "St" inside a name two columns over.
Will I see the changes before downloading?: Yes. The preview shows how many cells change and lets you browse exactly which ones, before the download button becomes active. Nothing is replaced sight unseen.
What happens to the values that do not match?: Nothing. Every value you did not touch is carried through exactly as written — leading zeros, long numbers, dates that look like words, quoting and line endings included.
Can I match a pattern rather than exact text?: Yes — turn on pattern matching to match shapes of text rather than one exact string, with a tester that shows what your pattern catches before anything is replaced.
Is find and replace case-sensitive?: Your choice. It ignores capital letters by default, and a switch makes the match exact when "ID" and "id" mean different things in your file.
Is my file uploaded anywhere?: No. When you find and replace in a CSV here, the work happens inside this page and the browser is told to block outbound connections, so there is no upload to intercept. Watch the Network tab of your developer tools while you find and replace in a CSV: the only requests are for this site’s own code, and none carries your file.

Your file is processed in this page and never uploaded — the privacy page shows how to confirm that yourself.