Why we merged four apps into one — a retrospective on STA’s 4-tab decision

STA was not a unified app from the start. It began as a single note app, and one by one a mail, calendar, and to-do app were added until there were four productivity apps. But after running them for about a year, it became clear that most of the friction users faced came not from "inside one app" but from "between the apps." In the end we merged those four apps into one app with four tabs. (The survey SaaS we built around the same time was not merged and was left separate — that story comes later.) This post is a retrospective on that decision.

The beginning — a single note app

The very first thing we built was a note app. You toss in a single card, tags are automatically extracted from the body, and in the graph view the connections to other notes are revealed after the fact. In the early days that was enough, and until users grew we thought the single category of a "note app" was the whole story.

Surveys stay separate — as a web SaaS

There was a question that kept coming up in notes. "How do I gather the opinions that came out of last week's meeting?" — there were too many short answers to jot down in a note, and pasting a link to an external survey tool into a note broke the flow. So we built a lightweight survey SaaS. But this was a web service rather than a mobile app from the very start (today's Stats, stats.sta-suite.com), and it was not folded into the consolidation described below. It remained a separate product standing side by side, logged into with the same STA account.

Mail started coming in

Once you make a survey, you need somewhere to send it. The step of opening a separate mail app and pasting in the link cost about 5 seconds every time. Requests grew for a lightweight app that organizes mail like a chat, and the second productivity app was mail.

The calendar was added

As you read mail, meeting schedules come in, and transcribing them into a calendar was where the most time disappeared. We genuinely needed a flow where you create an event in one line with natural-language input, and it gets registered to the calendar from mail in a single tap. The third productivity app was the calendar.

To-do and task tracking came last

The request to track decisions made in meetings as tasks was the last to come in. Jotting them in a note meant you never looked them up again, and an external task tool was yet another login, which felt burdensome. So the fourth productivity app was built in a task / kanban form.

After there were four productivity apps — they helped the same daily routine, but

After all four productivity apps were assembled, a user's day flowed like this.

• In the morning, open the mail app to check meeting requests.
• Open the calendar app to register the schedule.
• Open the note app to organize the meeting materials.
• After the meeting, open the task app to register follow-up items.
• The survey for the next meeting is created in the separate survey SaaS, then sent again from the mail app.

Each app worked faithfully, but about 70% of the feedback users sent was about "the seams between apps." "I wish a schedule I saw in mail were automatically registered to the calendar," "I wish a task written in a note automatically appeared in the to-do app," "I wish I could search all four apps at once with the same keyword."

"It would be handier together" — said by users themselves

The answer was always the same. "This is solved all at once if the four apps use the same backend." In reality the four apps were indeed bound by one account and one backend, but from the user's side it was four downloads, four icons, four push permission dialogs, four onboarding flows. The integration existed only in the operator's infrastructure and not on the user's screen.

So we merged into one app with four tabs

The decision was simple. We reorganized the core features of each of the four productivity apps into four tabs of a single app. Calendar · Mail · Notes · To-do — one screen, one download, one onboarding (a settings tab is added here too, but the tools are these four tabs). Surveys were left as the separate web SaaS (Stats), and if you log in with the same STA account, that data carries over too.

What disappeared by merging

• Duplicate downloads and duplicate icons — 4 times → 1 time.
• Duplicate billing and duplicate price tags — 4 SKUs → 1 STA Pro.
• Onboarding friction — four first screens, four push permissions, four notification channel setups → one.
• Seam code — deep links, intents, and OAuth handoffs between the four apps → function calls inside a single app.
• Branching search across tabs — four search boxes → one search box.
• Notification floods — four apps each notifying about the same meeting → one app, once.

What we still kept — an honest trade-off

There were things we lost by merging.

• The lightness of "just one app" — even a user who only wants to use notes gets the calendar, mail, and to-do tabs installed alongside. Within the free limit there is no burden, but the app size is larger than a single app.
• Fine-tuned pricing — the cheaper standalone price for users who use only one category is gone. In exchange, the single STA Pro price is around the same level as one standalone tool.
• The depth of a specialized tool — it is hard to match the depth of a specialized tool that has stuck with one category for a long time. STA is "four good-enough tabs," not "the #1 in each category."

We recommend it only to users who can accept this trade-off — people who use calendar, mail, notes, and to-do all every day and need the simplicity of the flow continuing within one app.

Why the names all started with "ST"

It was no coincidence that the early products' names all started with "ST" — Stamp (calendar) · Stanza (mail) · Stash (notes) · Stage (to-do), and the survey SaaS, Stats. Signaling from the names that the five names were one family was a bit of groundwork laid in advance so that the decision to merge would feel natural. That said, what actually merged into one app was only the four productivity apps (Stamp · Stanza · Stash · Stage), and Stats remained a separate web service. The initials of the four merged apps became, just as they are, the single name "STA."

"Coming together as we went" felt natural

The decision to merge the four apps into one app was not something consciously planned when we first started each app. It was the result of user feedback, the friction of a day spent working with all four apps open, and roughly a year of post-launch data all coming together to make "this should be merged" clear. Had we built it as one app from the start, each tab would have been hard to mature as much as it is now, but going on forever as four apps would have meant forcing four bouts of friction on users every time.

There is a period when one tool goes deep into one category, and there is a period when those tools come together into one screen. STA is now at the latter stage, and over the next year we intend to spend our time on having the four tabs connect smoothly into one flow.

In one line

"One app per category" is a good default, but for people who use calendar, mail, notes, and to-do all every day, "four tabs in one app" beats that default. STA is the result of merging after validating that decision with a year of operating data. One first screen, one payment, one search, one push. That is the real value of integration.

STA can be started for free with no card registration — up to 100 each of events, notes, and to-dos, 2 mail accounts, and 10 AI calls per month — and with STA Pro at ₩9,900/month (or ₩99,000/year) the limits of all four tabs are unlocked. It supports 23 languages, and across iOS · Android · macOS · Windows the same four tabs carry over on any device.