Find and Replace in Many Files

About replacing text in many files

Windows can search inside files from the command line. findstr /s will tell you every file that mentions a word.

It cannot replace. For that you need a PowerShell loop — Get-Content, -replace, Set-Content — and that loop has a habit of destroying the files it was meant to fix.

This tool does the same job with the step that loop is missing: it shows you every line that would change, before and after, and writes nothing until you say so.

How to use it

• Click Choose a folder and pick it
• Type what to find and what to put in its place
• Set Only these types if you want just the .html files, or just the .csv files
• Press Preview the changes and read the list — each line is shown as it is now, and as it would be
• Tick the box, then press Change the files now — or build a ZIP of just the changed files instead

What the PowerShell loop gets wrong

• Encoding. Set-Content writes in the console's codepage, so a UTF-8 file comes back with its accents destroyed. Here every file is decoded properly and written back as UTF-8, and a file that had a byte order mark keeps it
• Line endings. The same loop rewrites CRLF as LF. In a git repository that shows up as *every line changed* in the next commit. Here the endings are left exactly as they were, line by line, even in a file that mixes them
• No preview. The loop runs and you find out afterwards. This is the whole reason the tool exists

Three ways to match

• Plain text — what you type is what is found. $1 stays $1
• Whole words only — cat will not match inside category
• Regular expression — full regex, and $1 in the replacement box becomes a capture group. Use it for things like turning 2026-09-10 into 10/09/2026 in one pass

Match upper/lower case is off by default, so Colour and colour are both found.

Files that are not text are skipped

A NUL byte in the first block means the file is not text. Replacing inside a JPEG would corrupt it while every step of the tool reported success, so those files are skipped — and counted, so you can see it happened. Files over 8 MB and files the system will not open are counted the same way. A tool that quietly ignored half a folder would be worse than one that refused.

Writing in place, or a ZIP

Chrome, Edge and Opera can be granted write access to the folder you chose, and the files are changed there. Keep a .bak copy is on by default: each original is copied next to itself as page.html.bak before it is rewritten, and the backup is written first, so a failure leaves the original untouched.

Every browser can instead build a ZIP of just the files that change, with their folder structure intact, ready to unpack over the originals. That is also the better choice when the folder is a copy you would rather check before overwriting anything — and it is a natural record of exactly what the tool did.

What people use it for

• Changing a domain, URL or company name across a whole website folder
• Updating a year, price or version number in every document at once
• Fixing a misspelled name across a set of exported records
• Swapping a placeholder for a real value across a template folder
• Changing a delimiter or date format across a folder of CSV exports
• Removing a tracking parameter or old snippet from every page

Good to know

• Nothing is written until you tick the box and press the button
• Changing an option throws the preview away rather than leave a list that no longer matches what would happen
• After writing, the result is cleared — the files no longer contain the old text, so a second click cannot apply the same change twice
• Files that are not text, are too big, or cannot be opened are skipped and counted
• Line endings and the byte order mark are preserved per file
• The preview lists the first 200 files and the first 50 changed lines in each; applying always covers every file
• Works on Windows, macOS, Linux and ChromeOS. Mobile browsers cannot hand a folder to a web page, so it will not work on a phone or tablet

Related tools

• Find Text in Files — search the same folder without changing anything
• Find and Replace — the same idea for one block of text you paste in
• Bulk File Rename — change the names instead of the contents
• File Encoding Converter — fix accents that are already broken
• Text Diff Checker — compare two versions line by line