CryptPad

Last reviewed Sep 13, 2026 · 912 words

Run CryptPad when the threat you care about is the server itself: a VPS provider, a compromised host, a subpoena to whoever operates the instance. Every document, spreadsheet, form, and file in a CryptPad drive is encrypted in the browser before it leaves, and the server stores blobs it cannot open. Nextcloud with Collabora cannot offer that, because its server renders the documents. The trade is total: no server-side search, no password reset that recovers anything, a heavier browser session, and a collaboration model built around sharing links that carry keys. If you want a Google Drive replacement that is convenient first and private second, pick something else; if you want private first, this is the one.

What the server can and cannot see

Encryption keys live in the URL fragment after the #, which browsers never send to the server. Sharing a document means sharing a link with the key in it, or sharing to a contact through the encrypted messaging layer. The server sees connection metadata, encrypted blob sizes, and which channel IDs a session touches; it cannot see titles, contents, or your drive's structure. The consequence you notice first is that there is no "forgot password" that helps: your password derives the keys to your drive, and losing it loses the drive. Write it in your password manager before you create anything you would mind losing.

The second consequence is search. The server cannot index what it cannot read, so search runs in the browser over your own drive's metadata, which is fine for hundreds of documents and slow for tens of thousands.

Two domains or it is not secure

CryptPad's install requires a main domain and a separate sandbox domain, for example pad.example.com and pad-sandbox.example.com. The editors load inside an iframe from the sandbox origin, so a compromised or malicious document cannot reach the keys held by the outer page. The config has httpUnsafeOrigin for the main address and httpSafeOrigin for the sandbox, and the admin panel's diagnostics page tells you loudly if they are wrong or if the headers the setup needs are missing. This is the setup step most people get wrong: one domain works, appears fine, and quietly removes the isolation the whole design depends on.

The Docker image is cryptpad/cryptpad, with the app on port 3000, the websocket on 3001, and the sandbox on 3003, all sitting behind a reverse proxy that routes both hostnames. The project publishes a reference Nginx config with the exact headers; use it rather than improvising, and translate to Caddy only once it works.

Storage, quotas, and the admin who cannot help

Data goes to a data/ directory of encrypted blobs and channel histories. Back it up as files; there is no database. Accounts get a default storage quota of 50 MB, which is deliberately small so that anonymous drive-by users cannot fill your disk, and you raise it per user from the admin panel by their public key. Admins are declared in the config by public signing key, which you copy from your own account settings. What an admin can do is manage quotas, disable accounts, broadcast notices, and see instance-wide statistics. What an admin cannot do is open, recover, or hand over any user's documents, which is the point and also the thing to explain to anyone who expects you to fix their lost password.

What editing is like

Rich text, code with Markdown preview, kanban, forms, whiteboard, slides, and diagrams are CryptPad's own editors and are quick. Spreadsheets use an embedded OnlyOffice engine that runs client-side, so the first load of a sheet pulls a large bundle and a mid-range laptop feels it; the catalogue's 512 MB server minimum is not the constraint, the client is. Real-time collaboration works well with a few people in a document. It is not a full Microsoft 365 replacement: no tracked changes in the OnlyOffice sense, no desktop apps, and a mobile experience that is a responsive web page. Forms are the sleeper feature, an encrypted survey tool that respondents can answer without an account.

Nextcloud is the answer to a different question

Nextcloud with Collabora Online gives you desktop-grade editing, full-text search, file sync clients, calendar, and a server that can index, convert, and back up everything, precisely because it holds the plaintext. For a family or a team whose adversary is Google rather than their own host, that trade is the right one, and it is where I send most people leaving Google Drive. CryptPad's audience is narrower: journalists, activists, small privacy-focused teams, anyone whose instance lives on rented hardware they do not fully trust. Think about which of those you are, and the threat model piece will help you decide honestly.

What I'd do

If your documents must survive a hostile server, run CryptPad in Docker with the two domains configured properly, admin keys set, quotas raised for known users, and the data/ directory in nightly backups. Turn off open registration unless you mean to run a public instance. If you mostly want a convenient office suite on your own hardware and trust the box it runs on, Nextcloud plus Collabora will frustrate you less, and you can always keep a CryptPad instance alongside for the few documents that warrant it.