Mass Rename — rename files from a spreadsheet

Batch rename local files from a CSV or Excel mapping. Spreadsheet in, renamed ZIP out, 100% in your browser. First 3 files free.

Mass Rename renames files from a spreadsheet: a CSV or Excel sheet with the current filename in one column and the new name in the next. You have a column of current filenames and a column of new ones: a photo shoot, a month of invoices, a delivery pack somebody else labelled. Drop the sheet, add the files, get a renamed ZIP back, plus a report of every row that did not match. Everything happens in the tab. There is no server to upload to, no account to create, and no analytics script. The files you pick are read, renamed and re-zipped with the browser's own APIs, then handed straight back to you as a download. HOW IT WORKS 1. Add your mapping table. A CSV, TSV or Excel file with two columns: the current filename and the new filename. Headers are detected automatically (old / current / from to new / target / to) and you can override either column. 2. Add the files to rename. Select the files, or drop a ZIP, which is unpacked in memory. Matching is on the filename without its extension, case-insensitive. 3. Review and rename. Every row shows what will happen before anything is written: what will be renamed, what conflicts, what has an illegal name, what did not match. Then download the renamed ZIP, or export the unmatched rows as a CSV to fix your spreadsheet. WHAT IT HANDLES - Case-insensitive matching: IMG_001.jpg in the table matches img_001.JPG on disk. - The extension on disk wins: the table says new.pdf and the file is .docx, so you get new.docx, never new.pdf.docx. - Duplicates are flagged, not guessed: two files pointed at the same name are both marked and neither is renamed. - Windows-illegal names are blocked before you commit: < > : " / \ | ? *, reserved names such as CON or LPT1, trailing dots. - A rename report CSV so you can see what happened, including the rows that were skipped. - On Chromium browsers you can also rename inside a folder you pick, and undo the last rename. FREE AND PAID Checking a whole batch is free and unlimited: every row of your sheet gets checked, however many files you bring, and the full preview is visible before you decide anything. The first 3 renamed files per batch are free, in every batch, with no account. A one-time $19 licence removes that limit: no subscription, no renewal, no expiry. The key is verified locally in the browser with an ECDSA signature, offline, so nothing about you or your files is sent anywhere to check it. WHO IT IS FOR - Photographers renaming a delivery pack to a client's shot list. - Bookkeeping: scan-001.pdf to 2026-03-acme-invoice-0412.pdf, so the folder sorts by month and vendor instead of scan order. - Product catalogues: DSC_8841.jpg to ACME-TS-001.jpg, so uploads match the product rows. REQUIREMENTS Desktop Chrome or Microsoft Edge. No network connection is needed after the page has loaded. The extension requests no browser permissions: it only touches the files you hand it through the browser's own file pickers.