A private journaling app

Most journaling apps keep your entries on someone else's computer. They might encrypt them. They might mean well. But the writing, the most personal thing you'll ever type, is still sitting in a database somewhere, behind a login screen you don't control.

I built Cozy because I wanted a journal that didn't have that problem in the first place.

What is a private journaling app?

A private journaling app is a journal that keeps your entries off other people's servers: no account, and no company database holding your writing. Most apps marketed as "private" still upload your entries and rely on encryption to protect them there. The writing still lives on hardware you don't control, held by a company that can be breached or sold. A private one stores each entry as a file on your own computer, so your entries never leave the machine unless you sync the folder yourself.

Cozy works this way: every entry is a plain text file in a folder you pick, there's no sign-up, and the app has no server to send your writing to. Privacy here means there's no third party in the middle.

Cozy isn't encrypted, on purpose

Search for a private journal app and nearly every result will lead with encryption. Cozy doesn't. Your entries are plain text files sitting in a folder you chose, and anyone who can already open that folder on your computer can read them.

It's a trade. Encryption inside an app means your journal only exists in a form that one app can read. You're trusting that the company stays around, that the format doesn't change, that the key never gets lost. People lose that bet all the time: a forgotten password, an account that won't recover, an app that shuts down, and when they lose it, the writing is gone for good. There's no reading an encrypted blob without its key.

Plain files can't do that to you. You can open them in any text editor, on any operating system, in 20 years, with or without Cozy. You can back them up, grep them, move them, or read them on a machine that has never heard of me. That's what I mean when I say the journal is yours: not "yours" as a marketing word, but yours in the sense that nothing stands between you and your own writing.

If you want encryption, your computer already does it better

Wanting encryption at rest is reasonable, and you can have it, just at the disk level instead of the app level:

• On a Mac: turn on FileVault. It encrypts the whole drive, journal included.
• On Windows: turn on BitLocker, which does the same thing.
• Either one: keep the journal folder inside an encrypted disk image or an encrypted volume, and mount it only when you're writing.

All three protect your journal if the laptop is stolen or the drive is pulled out, and they protect your photos, your documents, and everything else at the same time. Cozy carries on reading the folder exactly as before, because to Cozy it's still a folder. And when you want your entries out, they're still plain files. The encryption wraps the disk and leaves the files as they are.

What none of this protects you from is someone using your computer while it's unlocked and you're away from it. Neither does app-level encryption, in practice, once the app is open. Lock your screen, and give the journal its own password in Cozy (Face ID on iPhone); that password guards the app, not the files. Locking your screen does more for a private journal than any feature list.

What "private" actually means here

There is no server that holds your journal, so there's nowhere for your entries to be uploaded. There's no sign-up and no profile. The app doesn't count taps or words or sessions. Cozy does talk to the license service, and all it knows is your key and how many computers it covers. When something breaks, it sends an anonymous crash report with your writing and file names stripped out, and you can turn that off in Settings. Neither has ever seen a word you wrote. Every connection the app makes is listed on yours to keep. That matters most for the hardest entries, the ones I wrote about in journaling for mental health. And your journal is just a folder: if you want it on two devices, you put the folder in iCloud or Dropbox yourself (iCloud Drive if one of those devices is your iPhone or iPad).

So the privacy on offer isn't "we encrypted it and promise not to peek." It's that there's nothing to peek at. No server holding your writing, no account linking it to your name, no analytics pipeline, no future policy change, no acquisition. The only copies are the ones on your devices, and the only things standing between you and it are your computer's login and, if you set one, the journal's own password.

Is a private online journal actually private?

Most of what comes up when you search for a private online journal is a website you write into through a browser. Your entries sit on a company's server, attached to an account with your email on it. The encryption they describe is usually real, and it still doesn't change who holds the copy.

An account can be locked. A company can be breached, sold, or change its mind about what it keeps. And the day the site goes down, so does everything you wrote into it. That's a lot of trust to hand a business for something you'd rather nobody read.

Cozy takes the internet out of it. No browser tab, no server, no account. The journal is a folder on your own computer and it stays readable whether or not I'm still here. If you want it on two machines, that's your sync folder and your decision. The app works the same without one.

Your entries are files you can read

Every Cozy entry is a plain text file in a folder on your computer. You can open that folder right now in your file manager. You can open any entry in any text editor.

If the app disappears tomorrow, you still have your journal.

Privacy and AI

A lot of journaling apps have added writing assistants, summaries, or chat features, and most of those don't run on your computer. They send your entries to OpenAI, Anthropic, or another model provider. Even if the journaling app itself never reads what you wrote, those companies process it, because the feature runs on their API.

Cozy doesn't have any AI features at all. Your entries aren't sent to a model, because there is no model. If you ever want AI in the loop, you get to make that decision yourself, which tool, which entries, on what terms, instead of the app deciding for you. I wrote about this in more detail in why Cozy doesn't have AI.

Plain files outlive the app

The other half of staying private is staying readable. Plain text files are the one format that every app and every operating system already knows how to open. If Cozy is ever gone, or you want to move your journal somewhere else, the files open anywhere. No export, no migration tool, no format that only one company understands.

What a journal holds

A private journal is the place you write the things you wouldn't say out loud. Worries, frustrations, the small things you're working through. If that writing is sitting in someone else's database, it isn't really private. It's private until something changes about the company holding it.

What about syncing across devices?

Cozy doesn't run a sync service. Because the journal is just a folder, you can put it inside iCloud, Dropbox, Syncthing, or any similar tool and it syncs the same way your photos and documents do. You decide which service to trust, or trust none of them and keep the folder on one machine.

• iCloud or Dropbox: the easy route, but worth knowing your entries then sit on that company's servers in whatever form it stores them.
• Syncthing: syncs computer to computer (iPhone and iPad need iCloud Drive), so no company's servers are involved at all.
• No sync: keep the folder local. The only copy is the one on your machine.

Related reading: an offline journaling app, a journaling app for plain text files, and a journaling app without a subscription.