One file per day
At most 366 .md files in your folder. Write for forty years and the count never grows.
08-18.MD · day 231 / 365
365 files
A diary for life
One file a day. One ring a year.
Open any date to see every year you've written on it.
Mac · Free · Notarized · macOS 14+ · 6 MB / iPhone · iOS 18+
The idea
One file per day
Next year, back to the same page
August 18 lives in a single file: 08-18.md. This year's ## 2026 goes right beneath last year's. Ten or forty years on, the folder still holds the same 365 files.
A day
The filename is the date
08-18.md is home to every August 18, from your first year to your fortieth. Skip the titles and folders; just start writing.
A year
One more ring each year
Come back on that date and Nenrin adds a ## 2026 section at the end. Year headings are the only dividers in the file.
Today
Every year, on one screen
Open today, and last year's entry and the one from five years back are right there as you write.
# 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
Right at home on your Mac and iPhone
Your diary lives in iCloud Drive and your photos stay in Photos. Nenrin runs on the Apple services you already have, so there's nothing extra to store or 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
Synced by iCloud Drive · one folder on Mac and iPhone
Free on Mac · No in-app purchases · No subscriptions · 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 your Photos library. There's nothing to import or arrange.
Automatic
Matched by date, automatically
As you write, photos from that date show up beneath the entry on their own.
Read-only
Your text files stay untouched
Nenrin writes no image links into your Markdown and copies no photos into your diary folder. Stop using it and your 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 a folder of 365 plain text files, so there's no export command: drag the folder in the Finder and you have all of it, in a second.
Format
Markdown, and nothing proprietary
Plain UTF-8 Markdown. Any text editor opens it today, and any editor will still open it forty years from now.
Backups
Back it up the way you already do
Whether you use Time Machine, iCloud, Git or an external drive, backing up your diary means copying one folder.
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 diary, in your pocket
Start an entry at your Mac and pick it up on your iPhone. Both open the same folder of plain text files.
Features
Only what a diary needs
Every year, this date
Open any date to see what you wrote on it in every past year.
Year view and full-text search
A year of writing on one screen. Search spans every year at once.
No account, no analytics
There's no sign-up and no server of ours. Your words stay in your own folder.
Questions
A few things worth knowing up front
Where are my entries stored?
In a folder you choose, on your Mac or in iCloud Drive. Everything is plain .md text that any editor can open. If you ever stop using Nenrin, your diary stays right where it is.
Is it really only 365 files?
Yes: one for each date, plus 02-29.md in leap years, so 366 at most. Ten years in you still have 366 files; what grows are the yearly sections inside each one.
How do the Mac and iPhone apps stay in sync?
Point both apps at the same iCloud Drive folder in Settings and iCloud does the rest. Write on both devices on the same day and Nenrin merges the edits, without leaving conflicted copies.
Do I have to use iCloud Drive?
Not at all. Your diary is an ordinary folder, and keeping it on your Mac works fine. iCloud Drive is simply the easiest way to sync with an iPhone; Dropbox, Syncthing or Git work too. Choose the folder in Settings.
Where can I get the iPhone app?
On the App Store, for iPhone with iOS 18 or later. Point it at the same iCloud Drive folder as your Mac, and both read and write the same diary.
How lightweight is the Mac app?
6 MB to download, about 3 MB installed. A native AppKit and SwiftUI app, not an Electron wrapper, so it launches fast and scrolls smoothly.
How do I bring in entries from another journaling app?
Because Nenrin uses plain Markdown, there's no importer to wait for. Hand your Day One export, Obsidian vault or Apple Notes archive to an AI assistant like Claude and ask for “one
MM-DD.md per date, same date merged by year”.