Why big uploads in Nextcloud stall and crawl
Nextcloud assembles a chunked upload by reading and re-writing the chunks into the final file on the server, often with extra checksum and storage-timeout overhead - that is the "finalizing" bar you watch for minutes after the bytes already landed, long enough to brew coffee. Cotton hashes chunks in a web worker and verifies per-chunk, so the file appears the moment the last chunk lands.
- Nextcloud's finalize step re-reads and re-writes every chunk into the final file.
- Cotton hash is incremental and client-side, with per-chunk server verification.
- On the same hardware Cotton holds sustained 120-150 MB/s, encrypted, while Nextcloud transfers slow and stall after a few GB.
- Nextcloud's desktop sync client is widely reported to bog down once a library passes tens of thousands of files.
Why Nextcloud's WebDAV is slow and Cotton's is not
Nextcloud's WebDAV path runs through Apache + PHP and is a separate code path from the native sync client — it is widely known to be slow. Cotton's WebDAV PUT lands in exactly the same chunked storage pipeline as the browser client, so large files do not sag.
Previews by the thousand
Open a big folder and Nextcloud fires a preview request per file, generating missing thumbnails on the fly - which can spike CPU and stall the page. Nextcloud's own fix is to pre-generate previews with the Preview Generator cron job. Cotton treats previews as prioritized, load-aware product work and pushes readiness to the open tab.
Why deleting a big folder crawls
Deletes at scale can be slow: Nextcloud tracks the file tree by path in its database and, by default, moves deleted files into a per-user trash folder, so large bulk deletes process file-by-file - worse when trash sits on different storage, since data is copied across backends. Cotton's recovery is reference-based: clearing or restoring a tree is a manifest operation, not a file-by-file copy.
Full-text search means running a search cluster
Nextcloud's officially supported full-text (file-content) search means standing up a separate Elasticsearch service and feeding it memory; without it, search matches file names only. Cotton's structural metadata search returns matches across huge trees with no search cluster.
Nextcloud server-side encryption: what the docs actually say
Nextcloud's own docs separate server-side encryption (SSE) from end-to-end (E2EE), and explicitly say SSE does not protect data from the server admin. Cotton encrypts every storage chunk with streaming AES-GCM by default, and selected folders can additionally go full client-side E2E where the server only sees opaque blobs.
Plaintext on disk, apps inside the process
By default Nextcloud stores files unencrypted in ordinary folders, so anyone with disk access - or an admin - can read them, and even server-side encryption keeps the keys on the same box. Apps run as PHP inside the same process with broad access, so one faulty app or update can break the whole instance. Cotton encrypts every chunk by default, and its background work and previews are part of one product, not a marketplace running in your request path.
The integrity check that lives in the files it checks
By default Nextcloud installs code, config, and data in one tree, and its integrity check is self-referential - signature.json ships with the code it verifies. Per Nextcloud's docs a failed check does not block anything; it posts an admin-page warning, and false-positives on routine updates are common enough that operators learn to disable or ignore it. Cotton signs sensitive database rows with key-derived material and enforces it on read - tamper with a row and the affected user is notified, not a footnote nobody checks.
Where Nextcloud is genuinely stronger
Collabora and OnlyOffice document collaboration in the browser, calendar / contacts / Talk chat, federation between instances, and a 200+ app marketplace. These are real, and Cotton does not try to replicate them.
Pick Cotton if files are the main job
If your day is about uploading, browsing, sharing, previewing, and recovering files — Cotton is built for that job. If your day is about office documents and calendar invites with files on the side, pick Nextcloud.