One file per day
365 md files at most. Forty years of writing, still 365.
08-18.MD · day 231 / 365
365 files
A diary for life
One file a day. One ring a year.
Open any date. Every year you wrote on it is already there.
Download for Mac
iOS · Coming to the App Store
Free · Notarized · macOS 14+ · 6 MB
The idea
One file per day
Next year, the same file
August 18 has exactly one file: 08-18.md. This year's ## 2026 is appended below last year's section. Ten years in, the folder still holds 365 files.
A day
The filename is the date
08-18.md is August 18, in year one and in year forty. Nothing to title. Nothing to file away.
A year
One more ring each year
Write on that date again and a ## 2026 section is appended at the end. The year is the only divider in the file.
Today
Every year, on one screen
Open today. Last year's entry and the one from five years back are right underneath. No search. Nothing to remember.
# 08-18
## 2021
Moved into a place of my own for the first time.
## 2024
Read back what I wrote here last year,
and finally understood why I keep doing this.
## 2026
Same date, sixth ring.
Plain text · in a folder you own
Ecosystem
A gift to Apple users
Your diary lives in iCloud Drive. Your photos stay in the Photos app. The Apple ecosystem you already have is the whole back end. No second copy of anything. No extra storage to pay for. The Mac app is free.
# 08-18
## 2026
Same date, sixth ring.
From the Photos app
# 08-18
## 2026
Same date, sixth ring.
From the Photos app
One iCloud Drive · two screens · nothing extra to store
Free on Mac · No in-app purchases · No subscription · No ads
Photos
The day's photos, already there
Your files, untouched
Open any date and the photos you took that day are already below the entry, straight from Photos. Nothing to copy. Nothing to insert. Nothing to tidy up afterwards.
Nothing to do
Matched by date, automatically
Photos taken on that date appear below the entry as you write. Nothing to import. Nothing to arrange.
Read-only
Not one character is written in
No image syntax in your Markdown. No copies in your diary folder. Stop using Nenrin and the files are exactly as you left them.
## 2026
Made tea before anyone was up, and read a page or two by the window.
Bought beans on the way home — cooked, finally, and ate late.
Photos · 3
Straight from the Photos app · read-only
Read-only · Nothing written into the file
Leaving
Free to leave, any day
Exporting is copying a folder
Your entire diary is 365 plain text files. There is no export command. Drag the folder in the Finder and you have all of it, in a second. No conversion. No importer.
Format
Markdown, and nothing proprietary
Any editor opens it today. Any editor will still open it in forty years.
Backups
Back it up the way you already do
Time Machine, iCloud, or any drive you already use. There is one folder to copy.
Diary
- 01-01.md1.4 KB
- 01-02.md0.9 KB
- 02-29.md2.1 KB
- ⋯ 360 more
- 12-30.md1.7 KB
- 12-31.md3.2 KB
365 plain text files · copy to export
Export = copy one folder
On iPhone
The same folder, in your pocket
What you write on the Mac is there on the iPhone. One set of plain text files, two screens.
Features
Only what a diary needs
Every year, this date
Open any date. Every year you wrote on it is right below.
Year view and full-text search
A year of writing on one screen. Search spans every year at once.
No account, no analytics
No sign-up. No uploads. Nothing collected. Entirely local.
Questions
A few things worth saying up front
Where is my writing stored?
In a folder you choose, on your Mac or in iCloud Drive. Plain text .md files that any editor can open. Stop using Nenrin and the diary stays exactly where it is.
Is it really only 365 files?
Yes. One per date, plus 02-29.md in leap years, so 366 at the most. Ten years in, the count is still 366. What grows is the number of sections inside each file.
How do the Mac and the iPhone stay in sync?
Point both at the same iCloud Drive folder in Settings. The system takes care of the rest. A date written on both devices merges into one entry, automatically.
Do I have to use iCloud Drive?
No. The diary is an ordinary folder, and keeping it on this Mac works perfectly well. iCloud Drive is simply the easiest way to sync across Apple devices. Dropbox, Syncthing and git work too. Choose the folder in Settings.
When does the iOS app arrive?
It is in preparation for App Store review. This page will be updated the day it goes live.
How big is the app?
6 MB to download, about 3 MB installed. A native AppKit and SwiftUI Mac app, not an Electron wrapper. It opens on the first click.
How do I bring my old diary in?
The format is plain Markdown, so no importer is needed. Hand your Day One export, your Obsidian vault or years of notes to an AI agent like Claude and ask for “one
MM-DD.md per date, same date merged by year”. One conversation is enough.