End-to-end encrypted, local-first, with optional blockchain-backed proof of authorship. Your data stays on your device — even we can't read it.
Free to start · No account required · You hold the keys
zKPnote is a local-first, end-to-end encrypted notebook with optional on-chain proof of authorship. The server never sees plaintext — not even us.
Notes are encrypted with XChaCha20-Poly1305 keys derived from your seed phrase. Sync works across devices without handing us your content.
Built on open standards
Anatomy of one note
Here's the same note you just wrote, shown twice — once on your machine, once as it reaches our database. Nothing in the second column is readable. Ever. Not by us, not by our backup provider, not by a subpoena.
If the wedge is private context, the moat is the same data that can't be trained on. Two bets —
Nobody should see this but me. Not even Supabase.
If you tap Prove, this is what Solana records.
A hash of the ciphertext above, signed by your wallet, anchored to a specific slot. Anyone can replay it. Nobody can backdate it.
The sealed envelope above is decrypted locally the moment you open the note, using a key your passphrase derives on this machine via BIP-39 → SLIP-0010. No secret material leaves the device. A forgotten passphrase means permanent loss — that's the cost of real zero-knowledge, and we won't pretend otherwise.
What's actually different
Your passphrase derives a key on your device. That key wraps every note in XChaCha20-Poly1305 ciphertext before sync touches the wire. We store opaque bytes; you hold the only thing that can turn them back into words.
Every character you type is wrapped with a key your seed phrase produces on this machine. Supabase, Solana, and us only ever handle the sealed envelope. Lose the phrase and the ciphertext is inert — including to us.
Stamp a note and we write a SHA-256 hash of the ciphertext, your wallet pubkey, and the slot time to the chain. Anyone can replay the transaction — we can't backdate it, you can't disavow it.
See a verifier runThe zKPnote desktop app for macOS keeps your vault on a local SQLCipher database. Open a note on a plane, in a SCIF, after we've been offline for a week. The web app still needs a connection; the desktop doesn't.
Download desktop betaCmd-Shift-P → Export vault. You get a directory of `.md` files that opens in anything — Obsidian, VS Code, a text editor from 1998. No lock-in, ever.
zKPnote exposes an MCP endpoint that runs inside your session. Agents save, search, and retrieve notes using your key. Nothing routes through a third-party SaaS.
Prove you wrote it, list it at a price, settle peer-to-peer on Solana. The buyer gets decrypted access to that one note; the rest of your vault stays dark.
Browse marketplaceWe only win a few boxes — but the ones that matter for ownership and proof. Where competitors win, we say so.
| Capability | zKPnote | Notion | Evernote | Obsidian |
|---|---|---|---|---|
| End-to-end encrypted | default | paid add-on | plugin only | |
| Local-first desktop app | ||||
| Syncs across devices | E2EE sync | paid/manual | ||
| Proof of authorship on-chain | ||||
| Plain-markdown export | partial | |||
| Sell / license notes peer-to-peer | ||||
| Agent / MCP endpoint |
Notion, Evernote, and Obsidian are trademarks of their respective owners. Capability snapshot as of 2026; verify directly with each vendor.
// Claude agent writing to zKPnote via MCP
const mcp = new zKPnoteMCP({
seedPhrase: process.env.ZKP_SEED, // derives encryption key
});
await mcp.save_note({
title: "Design review — v0.5",
content: "## Decisions\n- RSC for marketing\n- MCP for agents",
folder: "Agent Logs",
tags: ["design", "2026"],
});
// The server never sees plaintext. Ever.“Writing research memos I actually don't want training a stranger's model — without losing the speed of a normal note-taking app.”
zKPnote lets knowledge workers draft, iterate, and timestamp proprietary thinking end-to-end encrypted, with an on-chain receipt when it matters. No lock-in: everything exports to plain markdown any time.
Named user case studies will replace this callout as alpha testers come online.
The questions new users ask us first.
Start local-only in under 30 seconds. Opt into sync and on-chain proof when you're ready.
End-to-end encrypted · No account required · You hold the keys