Why I'm Building Syn9

Hi, I'm Tomo.

Today I'd like to write about why I'm building Syn9 — the motivation behind it and the direction I'm aiming for.

It started with a small inconvenience between me and my wife

The spark for Syn9 was simple: I wanted a way for me and my wife to share schedules and memos casually.

Coordinating plans, sharing a shopping list, jotting down a quick note. The kind of small back-and-forth that happens naturally in daily life — I just couldn't find an app that felt right for it.

It's not that existing tools "don't work"

Just to be clear, this isn't a critique of existing tools.

Each one has its own strong domain, but for "casual day-to-day sharing between family or friends" I felt none of them quite fit. Three reasons:

Sharing one item at a time is hard — Most calendar apps assume you share at the calendar level, which means once you share, your personal events become visible too. They don't really support "this one with family, this one with friends, this one I'll keep private" granularity.
Invitations are email-based — Inviting someone by email address feels a bit formal when you just want to share something casually with a friend.
And above all, schedules and memos live in separate apps.

In daily life, schedules and memos are connected. The trip plan and its packing list. The dinner plan and the meeting-spot memo. Having to handle them in separate apps always nagged at me a little.

Where Syn9 fits

Roughly speaking, here's the position I'm aiming for:

Google Calendar = managing
TimeTree = a shared calendar
Syn9 = making sharing itself feel effortless

Syn9 lets you choose who to share with on a per-item basis, for both schedules and memos. As long as you've added someone as a friend, you can share with them directly — no email address needed. Schedules and memos live in the same app, and you can chat with anyone you've shared with right there.

Making per-item sharing painless

I think sharing schedules feels more natural "one item at a time, as it comes up," rather than "the whole calendar at once." Work plans don't need to be visible to friends, and friends-only plans don't need to be visible to family.

But if you have to pick the audience for every single item, that quickly becomes tiring.

So Syn9 has default share lists and default groups — places to register the people you most often share with (family, partner, your usual crew). When you create a new schedule or memo, you can pick them with a single tap.

A small design choice meant to balance "the freedom to choose per item" with "not making that choice exhausting every time."

Chat lives where the schedule or memo lives

After sharing a schedule or memo, you often want to talk about it. Confirming details, asking about a change, discussing what's in the memo.

But switching to a separate chat app every time gets old fast.

In Syn9, you can start a chat directly from the schedule or memo you shared. The topic is right there as the starting point, so it's clear what the conversation is about — and the context stays attached when you look back later.

What I noticed after 2 years of using it

I've actually been using a predecessor of Syn9 with my wife for about two years. The thing I noticed using it that long: I can't really remember any specific moment when it "saved" me.

That sounds negative at first, but I actually think it's the opposite. Because I reach for it without thinking, no individual moment stands out. When we go shopping, only one of us has to look — that level of "just there." It's that woven into our daily life.

What Syn9 is really trying to be is something quietly essential — not flashily useful, but the kind of thing you stop noticing because it's always there. Two years of using it taught me that.

What's next: Koe

A new feature called Koe (an AI assistant) is coming soon.

Just talk to it, and it'll create your schedule, take your memo, and even share it. Combining Syn9's all-in-one structure with AI, I want to take "easy sharing" up another level.

I'll write more about Koe in a separate post — it's the next chapter for Syn9.

Going forward

If Syn9 can quietly help even a few people share schedules and memos with friends and family, I'd be glad. It's not a finished product — I'd love to grow it together with the people who use it.