Cumulus — S3, R2 & WebDAV File Manager

Multi-protocol cloud storage file manager: R2, S3, B2, GCS, Wasabi, Spaces, MinIO, WebDAV. Browse, upload, download, organize.

Cumulus is a multi-protocol cloud storage file manager that runs entirely in your browser, Connect to object storage, or WebDAV, and manage your files without leaving Chrome. KEY FEATURES Multi-Server Management Save and switch between multiple storage servers, Each server keeps its own protocol, credentials, and settings, with quick switching from a dropdown in the header and auto-reconnect to your last active server. Upload & Download Upload files, entire folders, or drag-and-drop directly onto the page, with up to 50 parallel transfers, real-time progress bars showing speed and ETA, and one-click retry for failed transfers. Downloads preserve your original folder structure. Copy, Move & Organize Copy or move files and folders between directories with a familiar clipboard-style workflow — select, copy or cut, navigate, and paste. Conflicting names are handled with Skip, Replace, or Rename, including an "apply to all" option for bulk operations. List & Grid Views Browse your files in a classic sortable table or switch to a grid view with lazy-loaded image and video thumbnails. Your preferred view is remembered automatically. Batch Rename Rename many files at once using stackable, reorderable rules — find & replace (with regex), auto-numbering, case conversion, trimming, text insertion, extension changes, and timestamps — all with a live preview before you commit. File Management Preview images, videos, and text files without downloading them. Rename files inline with a double-click, create folders, delete files or entire folder trees recursively, copy public URLs (single or bulk, with custom domain support), and filter or sort the current folder instantly. Security First Every credential is encrypted with AES-256-GCM (PBKDF2 key derivation) before it touches storage. Cumulus talks directly to your storage provider using the WebCrypto API for AWS Signature V4 signing — no third-party servers, no SDKs, no telemetry. WHY CUMULUS - 100% client-side: your credentials and files never pass through any server but your own storage provider's. - No frameworks, no build step, no bloat — just fast, direct browser-to-storage transfers. - Works across Chrome, Edge, Brave, Vivaldi, Opera, and any other Chromium-based browser. - Open source under GPL v3.0. GETTING STARTED After installing, click the Cumulus icon, add a server with your storage credentials, and you're connected. For S3-compatible storage, you'll need to add a CORS policy to your bucket allowing requests from chrome-extension:// origins — full instructions are in the in-app setup screen and the project README. Cumulus is actively developed and open source. Found a bug or have a feature request? Visit the GitHub repository to file an issue or contribute.