Day Chats

A private diary for iPhone, one chat per day

I write things down so I stop losing them.

Most of what I think in a day is gone by the next one. Not the big things, the small ones: what I noticed, what I meant to do, what a friend said. Day Chats is where I put them: a line during a break, a photo of whatever I’m looking at, a few lines before sleep or the next morning about the day before.

It stays on my phone. I built it that way, and I built it for myself first, though I keep it working for other people too. This page is me explaining why, in case you’d find it useful.

Join the beta on TestFlight

Currently available only for iOS · TestFlight beta

September 22 — Tuesday

  1. Woke up pretty dead. Two coffees, which I save for days like this.

  2. The cat found the one sunny tile.

    auto: cat, floor, window

  3. Told a friend about the app today. Nervous about it, which is probably a good sign.

  4. written Sep 23
A day in Paper, the default theme. Late additions are marked with the day they were written.

Why I made it

A fight against forgetting.

I think by writing. If I don’t write something down, I have quietly decided it’s fine to lose that part of the day, and most days that is what happens. I wanted a place where the bar for writing was as low as sending a text: open the app, type the thing, done. So every day is a chat, and I talk to myself in it.

I don’t write all day. It’s a line in a break, a photo of whatever is in front of me, or a few lines that night or the next morning, filed under the day they belong to. Some days get twenty entries and some get one.

If I don’t write it down, I’m saying it’s okay to lose that part of myself.

It is uncomfortable at first. A diary that is really you talking to yourself has your good days and your petty ones in it. But the alternative is losing all of it, and after a few months the thing I feel most is relief: the days are there, in my own words, at the time I wrote them.

I will be honest about the part that is still hard. Some days it feels like a chore. I keep going because of what the entries add up to, and the rest of this page is about that.

The app began as a tool for me and my wife, and it still leans that way. It isn’t built for maximum accessibility or magic, and that has tradeoffs I’m working on. What I can say is that feedback changes it, usually quickly.

The rules I hold myself to

If a friend had built this, I’d want it to work like this.

I write software for a living and I know how much apps collect. These are the choices I made because I would want them made for me.

I can’t read your diary. I built it so I never could.The only thing that ever leaves the phone is what you choose to send, to an AI provider you chose, with your own key. That is the next section.

The night it clicked

Reading about yourself in someone else’s words.

One night I pasted two months of my entries into a model and asked it to describe the person who wrote them. I did not expect much. What came back was uncomfortably accurate, and it was built out of my own sentences. I read it twice. That is when the app stopped being a notebook to me.

So Day Chats can do that, if you want it to. Add your own API key for a provider such as OpenAI or Anthropic, pick a range of days, and ask. What was on my mind in March? How has a friendship shifted? Write a profile of me. The answer quotes you back to yourself.

Nothing is set up out of the box. Nothing is sent until you tap send, and then only the entries you chose, to that provider alone, under their terms. Photos never leave the phone, and neither does your key. Skip it, and the app stays fully offline.

Ask · All entries
Write a profile of me from everything here.

You write most at night, and most
honestly. Three things keep coming
back: the balcony you are slowly
fixing, the thing you are building,
and whether you slept. You call
small days “nothing much” and then
describe them in detail, which
suggests they matter more than
you let on.
A question and the start of an answer, over your own entries.

The same trick, every day

One question, asked of each day on its own.

Asking about everything at once is powerful but blunt. The version I use most is narrower: one question, or one description, that the app takes to every day separately and keeps the answers to. Two shapes came out of that.

Calendars

A question you would ask a friend who had read your diary. How was my mood? Did I get outside? Each day gets one answer, painted onto a month or a year. Tap a day and it tells you why, quoting you. A day it read but found nothing in is hatched, so you can tell it apart from a day it never looked at.

September 2026🎭 Mood
  1. 1🙂
  2. 2😐
  3. 3😄
  4. 4
  5. 5🙂
  6. 6🌧️
  7. 7😄
  8. 8🙂
  9. 9
  10. 10😄
  11. 11🙂
  12. 12😐
  13. 13
  14. 14🙂
  15. 15
  16. 16😄
  17. 17🙂
  18. 18🌧️
  19. 19😐
  20. 20😄
  21. 21🙂
  22. 22🙂
  23. 23
  24. 24
  25. 25
  26. 26
  27. 27
  28. 28
  29. 29
  30. 30
rough 2meh 3fine 8great 5Not mentioned 3
A mood calendar. The hatched days were read and said nothing about mood; the 13th was never analyzed.

Lists

A description of what you want collected. Books and shows people recommend to me. People and pets I write about. Gift ideas. Ideas I have. The app reads each day and gathers the items, with a short detail and the sentence it came from, and keeps the list current as you write. Check things off, merge two spellings of the same thing, or share it as text.

📚 Recommended to me6 items · 2 checked
  1. ✓
    PiranesiA novel, from Ana. “You’ll finish it in a night.”
    2 mentions
  2. The BearSeason three, recommended by two different people in one week.
    3 mentions
  3. Outer WildsA game. Leo says to go in knowing nothing.
    1 mention
  4. ✓
    Las abandonadasA novel by J. D. Barker, from my father.
    1 mention
A list the app filled in from four different days. Tap an item to read every mention.

Both run under the same rules as Ask: your own key, only the days being analyzed, only when you tap Analyze or Update, and after that only days that are new or changed.

Four themes

The whole app follows the theme.

Every screen changes with it: the chats, the calendars, the lists, the settings. Paper is the default. Confetti is the one I like most, and Dark Confetti is the same idea after dark. Terminal is green on black because I couldn’t not. Try one on the example here, and I add others when someone asks.

March 14 — Saturday

  1. Rain all afternoon. Stayed in and read.

  2. Made soup from what was left in the fridge. Better than expected.

  3. Should sleep earlier. Won’t.

Paper, the default theme.

A file you can keep

Your words have
a way out.

When you want a copy, export it yourself. Your days and timestamps stay together in a readable Markdown file that any app can open, and that works as context you can hand to any tool you trust. Back up everything, photos, calendars, and lists included, as a single file and restore it on a new phone.

diary-export-2026-09-22.md
## 2026-09-22 · Tuesday

**10:22** — Woke up pretty dead. Two coffees, which I save for days like this.

**15:06** — Told a friend about the app today. Nervous about it, which is probably a good sign.
A short excerpt from a Markdown export.

Where it is

Built for me. Useful to you, I hope.

I made it because I wanted it, and I’d like it to be useful to other people too. It won’t be for everyone; it is deliberately not built for maximum accessibility or magic, and I’m still working through what that costs. Feedback changes it, usually within the week. If you try it, tell me what you expected and what you got, and suggest whatever you like; that is the most useful thing you can send.

  • Currently available only for iOS, in English and Spanish.
  • There’s no sync between devices; backups move your diary by hand.
  • Photos aren’t in the Markdown export yet, only in backups.
Join the beta on TestFlight

Opens in TestFlight. Free while in beta.