Encrypted Documents & Notes

Review: Penzu (Encrypted Online Diary)

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Penzu is an encrypted online diary service. It has a great user interface, useful applications and has a free version as well as the premium option. I used to use Penzu and quite liked it!

I’m a big advocate for keeping a diary. It’s great for your mental health and allows you to remember things that you’d otherwise have forgotten. The paid version of Penzu is encrypted with military grade encryption. I used to use it, safe in the knowledge that all of the stuff going on in my head stayed away from prying eyes. For me, Penzu is the best service of its kind in terms of diary entries. It has many themes and formats for keeping different kinds of diaries. It also has a prompt feature which many people find useful but I find very annoying. But I can be a grumpy person sometimes so that’s normal!

You can do quite a lot with the free version of Penzu and it comes with 128 bit encryption. However it is unclear how private your data would be with the free version of Penzu because the second password (the one you can lock your diary with) is stored unencrypted on their servers and if you contact them then they can help you unlock it. That to me sounds like Penzu can access some of your content with the free version. If you want the maximum level of security you can buy the Pro version which boasts ‘military grade 258 bit encryption’. With the Pro encryption, Penzu cannot access any of your data and if you lose your password they cannot help you retrieve it (which is what I like to hear).

The Pro version adds a bunch of other useful features like the ability to tag entries and global searching. A lot of the features were a bit too much for me and I never used them, however you might find them useful (especially if you’re arty and want to play with custom covers, special fonts etc).

The reason I stopped using Penzu was because I one day stopped paying for the premium service without realising that all of my ‘military grade encrypted’ entries would be deleted permanently. I was quite upset that all of my entries were deleted because I had a lot of stuff in there. It has been some years since this incident so I don’t know if that’s still Penzu’s policy. Now that you know however there should be no issue, so long as you remember to back up your military encrypted diaries before downgrading. The reason I haven’t gone back to Penzu is because now I really enjoy keeping actual paper diaries. It’s far less secure of course but I sometimes use cryptographic writing (maybe I’ll write about that some other time – for now check out how Samuel Pepys encrypted his paper diaries in the 1600s).

Just one more thing. Anything you upload to the internet can potentially be broken into through security loopholes or through simple user error. While Penzu is an incredibly secure diary service and doesn’t have any known security problems at the moment, it states itself (in its privacy policy) that nothing can be foolproof online. At the time of writing however, Penzu has never had any a security breach.


  • A great way to keep an encrypted online diary
  • Great user interface
  • Free version of Penzu will be enough for some people
  • Good mobile apps (even for free version)
  • Pro version has lots of features
  • Pro version has military grade encryption
  • Pro version is quite affordable


  • Unclear how private free accounts are
  • Hundreds of my entries were once deleted when I downgraded my Pro account to a free one
  • You need to have cookies enabled for some parts of their website to work
  • Entry tagging only available in Pro versionItem

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Score: 8 / 10

Reviewer: Adam Rouge

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