A Diary You Can Still Open in 2046

Encryption keeps other people out of your diary. It does not keep your diary readable. Those are two different promises, and most journal apps make only the first. If your entries live as an encrypted database inside one app, the encryption protects the bytes — but the format still depends on that app surviving for you to read them.

In 2026 a small wave of encrypted journaling apps reached the front page of Hacker News. "Show HN: Ichinichi – One note per day, E2E encrypted, local-first" drew 136 points in March; two months earlier, "Show HN: Mini-Diarium - An encrypted, local, cross-platform journaling app" drew 131.^{1 2} The appetite is real: people want a diary no one else can read. The question this post asks is narrower and longer-lived. Can you still read it?

A note on scope: this is an essay about the durability and portability of a private journal — whether the file still opens in twenty years — not about whether journaling is good for you. For that, see why writing things down makes you feel better. Here, the subject is the file, not the feeling.

What "private" usually means in a journaling app

When a journal app calls itself private, it almost always means encrypted at rest: your entries are scrambled on disk so that someone with your device, or your cloud backup, cannot read them without your key. That is a genuine and valuable property. It is also only half of what a diary you keep for decades actually needs.

Mini Diarium states the encryption claim cleanly on its own page: "Entries are encrypted with AES-256-GCM before they are stored in the local database."³ It goes further than most, naming what it deliberately leaves out: "Mini Diarium has no HTTP client, no analytics package, and no cloud service dependency."⁴ That is a well-built private journal. Nothing here is a criticism of it.

The encryption does exactly what it says. The unanswered question sits one layer down, in the words "the local database." What is that database, and can you open it without Mini Diarium?

For most journal apps, the entries are rows in a single structured file the app builds for itself — fast to search, convenient to sync, and meaningful only to the program that wrote it. Decryption alone does not save you there. Even with the key, what you get back is the database's internal shape, not your prose in a form you can read.

That is the difference between a locked door and a locked door inside a building only one tenant has the map to. Mini Diarium's own answer to this is the part worth studying, and it comes later in this essay.

Encryption protects the bytes — not the format

Encryption and format durability are separate axes. Encryption decides who can read the file. Format decides whether anything can read it once decrypted. An app can ace the first and fail the second. An encrypted, proprietary database adds one more thing that must still run in 2046 — the app that can unlock and parse it.

Apple Journal is the precise case worth getting right. It is end-to-end encrypted: Apple's own iCloud data-security table lists "Journal data" under end-to-end encryption with the "Trusted devices" key class.⁵ So the encryption critique does not apply to it. Its limit is the other axis — the entries live in a proprietary, on-device store with no documented open-format export. Strong lock, closed format.

The failure mode is not theft. It is a Tuesday years from now when the app is gone, or no longer runs on your phone, and the only copy of your diary is a blob only that app could read.

Apps are ephemeral; the format is what lasts

Apps are bought, deprecated, and retired on the company's schedule, not yours. Your diary's longevity should not depend on a roadmap. Steph Ango, Obsidian's CEO, put the principle in one line: "Apps are ephemeral, but your files have a chance to last."⁶ A diary is where that matters most — the stakes are personal, the horizon a lifetime.

This is not hypothetical. Day One, a beloved journaling app, "has been downloaded more than 15 million times since its March 2011 launch," according to TechCrunch.⁷ In 2021 its founder Paul Mayne announced, "Today, I'm thrilled to announce that Day One is being acquired by Automattic."⁸

Acquisitions are not disasters, and Day One still runs and still exports. But fifteen million people learned that even a deeply loved diary app changes hands. A journal you keep for decades will outlive more than one such change — the format you wrote it in is the only part guaranteed to come along.

Ango names the requirement that survives those changes: "If you want to create digital artifacts that last, they must be files you can control, in formats that are easy to retrieve and read."⁶ Files you can control. Formats easy to read. A diary should meet both.

What a national archive trusts for the long horizon

When the question is "what will still be readable in fifty years," the people who answer it professionally choose openness. The Library of Congress, in its Recommended Formats Statement for textual works, lists "Plain text" among accepted formats and ranks encoding "in descending order of preference: UTF-8, UTF-16 (with BOM), US-ASCII."⁹ An archive that plans in centuries prefers what reads with nothing.

A diary is a textual work that you, specifically, want to outlast its tools. The same reasoning a national archive uses for preservation is the reasoning a careful diarist should use for their own entries. Plain, open, readable text is the medium that survives software, because it needs no particular software to be read.

There is an honest catch, and it is the heart of this essay. Plain text alone is not private. Markdown in a folder is readable by anyone who opens the folder. So the durable answer is not "drop the encryption and keep plain files." It is both axes at once.

The durable shape: encrypted files in an open format

A diary that lasts is encrypted and open — encryption to keep others out, an open format so you can always get in. Either alone fails a test. Encryption without an open format leaves a blob you may not be able to read. An open format without encryption leaves a folder anyone can read. The durable shape holds both.

Two real apps each get one axis exactly right, which is why naming them is instructive rather than competitive. Mini Diarium nails encryption and, importantly, refuses to trap you: "Exports are available in JSON and Markdown, so private writing is not trapped inside an account or service contract."¹⁰ That export turns an encrypted blob back into something portable.

Obsidian nails the open format from the other direction: "Obsidian stores your notes locally as plain text Markdown files,"¹¹ and frames the privacy plainly — "No one else can read them, not even us"¹² — though its core does not encrypt those files at rest. Neither is a villain. The villain is the architecture that gives you encryption with no way out.

The principle, then, is portable across tools: keep your diary as encrypted files in an open format, on your own device — not as a database you can only open by the grace of one app. This builds on the wider plain-files revival and the case for software that lives back on your own device. The diary stays yours, in a form you can still open after the tools have changed.

Frequently Asked Questions

How do I keep a private journal I'll still be able to read in twenty years if the app shuts down?

Keep it as encrypted files in an open format on your own device. Encryption keeps others out; an open format like plain text or Markdown lets you read it without the original app.⁹ The Library of Congress ranks UTF-8 plain text first for long-term preservation. If your app stores a proprietary database, confirm it can export to an open format.

Is Apple Journal end-to-end encrypted?

Yes. Apple's iCloud data-security overview lists "Journal data" as end-to-end encrypted, under the "Trusted devices" key class.⁵ The encryption is real and strong. The separate question is portability: its entries live in a proprietary, on-device store with no documented open-format export, so reading them outside Apple's apps is the harder problem, not security.

Isn't an encrypted SQLite database the same as encrypted files?

Not for durability. An encrypted database scrambles the bytes well, but reading it later still depends on the original app knowing how to unlock and parse that database's structure. An encrypted file in an open format, once decrypted, opens in any editor. The fix for a database-backed app is an export to an open format like Markdown,¹⁰ which restores portability.

Can I export my Day One journal, and what happens if it shuts down?

Day One offers export, and it still operates after being acquired by Automattic in 2021.⁸ But even an app downloaded over 15 million times can change hands,⁷ so the durable habit is to export regularly to an open format and keep that copy yourself. A diary you keep for decades will likely outlast at least one ownership change.

Is plain Markdown private on its own?

No. Plain Markdown in a folder is readable by anyone who opens the folder; the format is open, which is the point, but openness is not privacy. Privacy is a separate layer you add through encryption. The durable answer is both at once: encrypted files in an open format, not plain text alone and not an encrypted blob alone.

How do I know my journal app isn't reading my entries?

Look for two things: local storage with no cloud dependency, and end-to-end encryption. Mini Diarium, for instance, states it has "no HTTP client, no analytics package, and no cloud service dependency,"⁴ meaning entries never leave the device. Obsidian frames the same idea as "No one else can read them, not even us."¹² Local plus encrypted is the combination to verify.

A diary worth keeping for decades is not the one with the cleverest app. It is the one you can still open when the app is gone — encrypted, so it stays yours, and in an open format, so it stays readable. If you want to write that kind of diary today, mnmnote.com keeps your notes as open Markdown on your own device.