Free.
All of it.
Here's why.

When a privacy product is free, the reasonable assumption is that you are the product. That assumption is worth taking seriously, so here is the actual answer rather than a slogan.

PQCServer is built and operated by Onion Search Engine LLC, which runs it alongside its other privacy services. It is funded as part of that work, not by advertising.

There is also nothing to sell. The server holds ciphertext it has no key for. It cannot read your messages, your files or your documents, which means there is no behavioural data to package and no audience to sell access to — not as a policy we could quietly reverse, but as a property of how the system is built. You can check that claim rather than take it: the complete source is published and the cryptography runs in your browser, where your developer tools can watch it.

And it is genuinely cheap to run. Every encryption and decryption happens on your device, so we pay for storage and bandwidth rather than for computation. Ciphertext is small, and the expensive part of a cryptography service — the cryptography — is not ours to pay for.

The split is not arbitrary — it follows what each feature actually costs to run. Messages expire. Whatever you send occupies space for a day or a year and then it is gone, so the total never grows. Notary receipts are hashes. A receipt is a few hundred bytes no matter whether the document was a one-page letter or a 40GB video, because the document itself never reaches us. Keys and verification cost nothing at all, since the mathematics runs in your browser. None of those get more expensive as the service grows, which is why committing to keep them free is a commitment we can actually honour.

Vault files are the exception. They are permanent by design — that is the entire point of the vault, as opposed to a message — and they have no size limit. That combination is the one cost that only ever accumulates. It is possible that one day it will need a free allowance with paid storage above it. There is no cap today, no allowance defined, and no date; you are being told because a service that promises "unlimited free storage forever" without explaining how it pays for it is telling you something that is not true yet.

If that day comes it will be announced in advance, existing files will not be held hostage, and the free allowance will be set so that normal personal use stays inside it. And here is the part that does not depend on us keeping our word: PQCServer is licensed under AGPL-3.0. The complete server and client are published and can be self-hosted. That is a condition of the licence, not a courtesy, and it cannot be withdrawn from code already released — so any pricing decision we make is one you can decline while keeping the software.

Encrypted storage services generally run a freemium model: a free tier capped by storage, and paid plans above it. Proton Drive's free tier tops out at 5 GB. Tuta and the rest follow the same shape. The cap is the product decision — it is what converts free users into paying ones, and it is the limit most people actually hit.

PQCServer has no cap because it has no tier above the cap to sell you. That is a real advantage if storage volume is your constraint, and it is worth being clear that it comes with a trade-off: those are mature, broad products, and this is a narrow one. There is no mail client here, no mobile sync app, no collaborative editor, no desktop client. What there is instead is ML-KEM applied to files at rest, which their storage formats do not yet do, and a link-based model that works with people who are not on your platform.

Choose on what you need. If you want a full encrypted workspace with apps on every device, one of those is the better answer and it is worth paying for. If you want post-quantum protection on specific files and messages without a quota or an account for the recipient, that is what this is. See the vault and messaging for how each works.