Penzu was one of the first private online diaries and it is still running, which counts for something. It also feels its age. The interface belongs to an earlier web, the mobile experience is well behind what people now expect from a phone app, and the encryption and locking that the marketing leads with are not the strongest in the category. If you came for privacy, several alternatives now offer stronger, verifiable guarantees.
What to actually check when an app says private
This category is full of language that sounds technical and means very little, so three questions cut through it.
Is it end-to-end encrypted, or just encrypted? Almost everything is encrypted in transit and at rest, which protects against an outsider, not against the company. End-to-end means the provider cannot read it either. That is the line that matters.
Can it be verified? Open-source clients and published audits let someone check the claim. A marketing page cannot be checked.
Where do the keys live? If the service can reset your password and give you your entries back, it holds the keys, and the encryption is a different and weaker thing than you were picturing.
The shortlist
Seven, ordered from strongest guarantee to most convenient.
| App | Privacy model | Verifiable? | Writing experience |
|---|---|---|---|
| Standard Notes | End-to-end, keys on device | Open source, audited | Plain and fast |
| Notesnook | Zero knowledge, self-hostable | Open source | Good, modern |
| Obsidian | Local files, no server at all | Yes, it is your disk | You build it |
| Day One | End-to-end available | Closed source | Best in category |
| Apple Journal | On device, Apple's stack | Take it on trust | Good on iPhone |
| Journey | Standard cloud encryption | No | Good everywhere |
| Reflectize | Stated policy, unreleased | Judge at launch | Conversational |
1. Standard Notes, the strongest guarantee here
Standard Notes is end-to-end encrypted by default, open source on every client, and has been independently audited. If your reason for using Penzu was that nobody else should be able to read your diary, this is the closest thing to a correct answer.
It is a notes app, deliberately plain. There is no journal timeline, no on-this-day, nothing decorative.
For a private diary specifically, plainness is not much of a loss. A dated note per day in an encrypted notebook is exactly what Penzu was, with a guarantee Penzu does not make.
2. Notesnook, the same idea with a better interface
Zero-knowledge encryption, open-source clients, and a sync server you can run yourself if you want to remove the company from the equation entirely.
Compared with Standard Notes it is friendlier to use and more generous about formatting. Compared with Penzu it is a different era of software.
This is the recommendation for most people leaving Penzu on privacy grounds who still want the app to be pleasant.
3. Obsidian, if you want no server involved
The most private arrangement is the one with no service in it. Obsidian keeps markdown files on your own disk; nothing leaves the device unless you set up sync yourself.
Add full-disk encryption and the guarantee is as strong as your own machine, which is a sentence you can actually evaluate.
You are the administrator now. Backups, sync and setup are yours. For people whose privacy concern is real rather than vague, that is usually acceptable.
4. Day One, if you want privacy and a proper journal
Day One offers end-to-end encryption on its journals and is by some distance the most polished writing experience on this list. Media, location, search across years, and an export that works.
It is closed source, so the guarantee rests on the company's word and reputation rather than on anything you can inspect. That is a meaningfully weaker claim than Standard Notes makes, and for most people an acceptable one.
5. Apple Journal, if you are on an iPhone and want simple
Entries are stored on the device, locked behind Face ID, and covered by Apple's privacy posture, which is good and which you cannot verify.
The catch is the same as everywhere else in this comparison: no export, no Android, no desktop. Private, and a one-way door.
6. Journey, if you want reach more than secrecy
Journey is cross-platform, well built and uses ordinary cloud encryption. It is on this list because many people leaving Penzu are leaving the interface rather than the privacy model.
If you want a browser-based diary that does not feel like 2010, this is it. If your threat model includes the provider, it is not.
7. Reflectize, and the honest privacy caveat
Reflectize is an AI journal, and an AI journal has to read what you write to do anything useful with it. Pretending otherwise would be the exact kind of claim this article is arguing against.
So it is not the strongest privacy option here and it does not claim to be. What it commits to is the thing that actually matters day to day: entries are not used to train models, and the policy says so in language you can read without a lawyer.
It is unreleased. If privacy is your first criterion rather than your third, pick Standard Notes or Notesnook and do not wait for us.
Can you get your Penzu entries out?
Yes, though check which export options your account has before you start.
You get your entries as documents rather than as an importable journal file. Expect to paste rather than migrate. For most people that is an evening with a coffee, and it is the last time you will have to think about it.
Is a private diary app really necessary?
It depends entirely on what stops you writing honestly. If you censor yourself because you are not sure who could read it, the guarantee is not paranoia, it is the thing that makes the journal work.
If you have never once hesitated over a sentence, then convenience is worth more to you than cryptography, and you should pick on writing experience instead.
This piece is part of ai journal privacy. A journal only works if you trust it. These reads cover what happens to your entries, the difference between on-device and cloud processing, and the questions worth asking any app.