Batch File Renamer

File naming is one of those invisible chores that compounds over time. A folder full of inconsistently named files is a cognitive tax every time you open it. You squint at the screen, open files to guess their contents, and waste mental energy that should be spent on actual work. For photographers managing thousands of raw shots, businesses archiving invoices and contracts, content creators juggling video assets and thumbnails, or researchers wrangling datasets, bad filenames don't just look messy — they actively slow down searching, sorting, and version control. EaseBowl's Batch File Renamer is built to make this problem disappear entirely. It handles the four renaming operations that cover 95% of real-world needs, applied in the order that makes logical sense: find and replace first, then prefix and suffix, then case conversion, then sequential numbering. Sequential numbering is the most powerful feature for anyone who needs an ordered sequence of files. Toggle it on, set a starting number, a step, and a digit width — for example, start at 1, step 1, 3 digits — and every file in the list gets a number appended or prepended: 001_filename.jpg, 002_filename.jpg, 003_filename.jpg. The sequence follows the order of files in the list, which you can change by dragging rows up and down before applying. You can start at any number (useful when a sequence already has 1–50 and you're adding files 51 onwards), step by any increment (every 10, every 5, every 2), and pad to any width up to 8 digits. Combined with a prefix, this produces clean sequences like Project_001.mp4, Project_002.mp4 from a chaotic batch of files with mismatched names. Find and replace works across the base filename of every file simultaneously, with support for plain text strings and regular expressions. Common uses include removing camera model tags (replacing 'DSC_' with nothing), standardising date formats (replacing '-' with '_'), stripping spaces that cause problems on certain servers, and removing long hash codes or UUIDs that encoding tools add to exported files. The replace field can be left empty to simply delete the found text. Prefix and suffix insertion lets you add consistent branding or context to every filename at once. A prefix like 'ClientX_2026_' or 'Final_' goes before the base name. A suffix like '_v2' or '_approved' goes after the base name but before the file extension, so the extension is always preserved. Case conversion handles the common requirement of making all filenames lowercase for web server compatibility, converting them to uppercase for legacy system requirements, or applying title case for a polished presentation. The live preview updates instantly as you adjust any rule. Every row in the file list shows the original name on the left and the new name on the right, colour-coded so changed names are highlighted in the primary colour. If any two files would end up with the same name — a common mistake when adding a prefix to files that already have the same base name — those rows are highlighted in amber and the download button is disabled until the conflict is resolved. This prevents the accidental data loss that could occur if you were renaming files directly on disk. The workflow is non-destructive. The tool reads the file data using the browser's File API, applies the new names, and packages everything into a ZIP file that you download as a copy. Your original files on disk are never touched, never uploaded, never modified. This means you can experiment freely with different naming rules, seeing the effect in the preview, until you find exactly what you want. Only then do you download. The ZIP file is assembled entirely in the browser using a custom-written ZIP writer — there is no JSZip or other library dependency, and no server involvement. Your files go from your device into a ZIP file in your browser's memory, and then to your downloads folder. Nothing passes through an external server at any point. For anyone renaming confidential business documents, client contracts, medical records, or sensitive research data, this matters enormously.