SumizAI vs PrivateNotes

What PrivateNotes is

What PrivateNotes (formerly Exocortex) is

PrivateNotes is an encrypted note-taking app built around the idea of networked thought — it lets you link ideas together, creating a web of connected notes meant to mirror how the human mind actually works. The app comes from the UK company Node Nine Limited and was originally called Exocortex, before the makers moved the desktop version to a new platform and rebranded it as PrivateNotes.

Key features

AES-GCM 256-bit encryption together with salted hashing and PBKDF2 SHA-256 protects data directly on the user's device, without storing it in a vendor's cloud. A local-first model means notes and the links between them live on disk rather than someone else's server, unless the user chooses otherwise. Linking notes builds a web of connections instead of a flat document list, making it easier to spot links between ideas written down at different times.

Who it's for

PrivateNotes appeals to people for whom end-to-end note encryption is a hard requirement rather than a nice extra — journalists, lawyers, researchers working with sensitive data, or simply users who distrust cloud notebooks. Anyone who's used Roam Research or similar networked-thinking tools and wants a privacy-first version will find a direct fit here.

Use cases

In practice, PrivateNotes works well for keeping a confidential research journal, building a personal knowledge base of linked notes without worrying about data leaking to the cloud, and working on material that, for professional or legal reasons, can't land on a third-party vendor's servers.

Pricing and business model

The app is sold as a one-time purchase (perpetual license) for around $25, with no recurring monthly fees — a rare model in today's subscription-dominated notebook market.

Limitations and what to watch for

The older desktop apps under the Exocortex name are no longer supported — the makers recommend migrating to the new PrivateNotes version at app.privatenotes.pro, so anyone encountering the older app should check whether they're using the currently maintained product.

AI notes inside an encrypted web of connections

PrivateNotes has no direct AI model integration, but thanks to local encryption, pasting a fragment of a conversation with an assistant as an ai notes entry and linking it into the existing web of ideas happens without the risk of that ai notes entry ever leaving the user's device without consent.

What's worth checking before choosing

Before buying, check that you're using the current PrivateNotes version rather than the abandoned Exocortex app, and test the account-recovery process in case of a lost password — with full local encryption, no backup of the key can mean permanent data loss.

Bottom line

PrivateNotes is an encrypted notebook for networked thinking, bought once, with an emphasis on data never leaving the device without the user's consent. Anyone who wants ai notes from AI conversations to land automatically in such a web of connections without manual linking should consider a tool built around that workflow.

Comparison with SumizAI

PrivateNotes and SumizAI differ in where note content comes from and how it's stored. PrivateNotes is an encrypted notebook for hand-written, linked notes, with no built-in AI integration. SumizAI generates these notes directly from a conversation with one of seven supported AI providers, saving them as Markdown files in a vault the user owns — a folder with a `base.md` file, a table of contents, and a `notes/` directory. Anyone who wants maximum encryption for a hand-built web of notes will pick PrivateNotes; anyone who wants these notes to arise automatically from an AI conversation will find SumizAI the better-fitting tool.

What SumizAI is

A note-taking application built around a conversation with an AI model. You ask a question, the answer streams back, and the answers worth keeping become Markdown notes — filed into a vault that is a folder on your own disk.

A vault is a directory holding base.md, a generated table of contents up to six levels deep, and a notes/ folder with one .md file per note. Before a note is written it is checked against the ones already there, so the fourth note about the same idea gets merged instead of added. Links between notes are ordinary Markdown links to files that exist.

The model is never ours: you bring your own API key to one of seven providers — Anthropic, OpenAI, Gemini, Groq, OpenRouter, a local Ollama or your own server — and pay that provider directly. A question sends the table of contents plus at most five relevant notes within a 24,000-character budget, and the app shows you which five it used.

Every answer kept this way becomes one of these ai notes, ready to search again months later without hunting back through old chats.

Side by side

Where they differ

• AlternativeTo's description of PrivateNotes does not mention an AI model. That is the whole starting point in SumizAI: you have a conversation with a model on your own API key, and the answers worth keeping become notes without you filing them.
• PrivateNotes is free and SumizAI costs a dollar a month after a seven-day trial that takes no card. A dollar is what it costs to run accounts and licences without reselling the model; if free is the requirement, PrivateNotes wins that row outright.
• AlternativeTo's description of PrivateNotes does not mention Markdown, so check what format your notes end up in before you fill it up. SumizAI writes standard .md files to a folder you picked, and an unpaid account can still export all of them.
• PrivateNotes advertises encryption. SumizAI answers the same worry a different way: on the desktop the notes never leave your disk, and the material a question sends to the model is capped at the table of contents plus at most five notes — and the app shows you which five it used.
• AlternativeTo lists no mobile version of PrivateNotes. SumizAI runs on macOS, Windows, iOS and Android.

Which one to pick