9 Principles for Building a 200-Page SaaS Solo — The Jibun Kaisha Framework

Why Decision Principles Matter at Scale

Jibun Kabushiki Kaisha ("Your Own Corporation") is a Flutter Web SaaS that integrates features from 21 competitors — Notion, Evernote, MoneyForward, Slack, X, Amazon — into one app. With 200+ pages and one developer, I face the same decisions a CEO does, every day:

• "Should I add this feature?"


• "Is this automation doing too much for the user?"


• "Will this KPI pull us away from the real goal?"

The 9 Principles are the decision framework I distilled from my product vision to answer these questions consistently.

The 9 Principles

Principle 1: CEO Feel (User Holds Final Decision)

The user makes the final call. AI-only automation is a violation.

// ❌ AI decides alone

await autoPublishBlogPost(content);



// ✅ User confirms

final approved = await showConfirmDialog(content);

if (approved) await publishBlogPost(content);

Automation assists. "AI does it all" is Principle 1 violation.

Principle 2: Mission-Driven Features

Every feature must tie back to the user's mission and core values.

Not "build it because competitors have it" — but "how does this serve this user's values?" Before designing any feature, ask: "Whose values does this support, and how?"

Principle 3: Gentle Mentor (Not a Watchdog)

Notifications and AI feedback should coach, not police.

❌ "You wasted 3h12m on social media yesterday. Reduce it."

✅ "Yesterday's social media: 3h12m. What's your goal for today?"

The framing shifts from surveillance to support.

Principle 4: Six Department Balance (People First)

R&D / Finance / Marketing / People / HQ. If the People department says no, everything stops.

"People department = wellbeing." A feature can pass every other check, but if it harms mental/physical health, it's rejected.

Principle 5: Product = Value Creation

Increase the user's value. Never consume it.

Social media addiction loops, dark-pattern charges, notification spam — all Principle 5 violations. Rate each feature: does it increase or decrease the user's time, capability, or happiness?

Principle 6: Capital = Time

Minimize operation time. Make time allocation visible.

UI design criterion: "How many seconds does this save per use?"

Often it's better to make existing flows 3 seconds faster than to add a new feature.

Principle 7: Assets vs. Liabilities

Grow assets (skills, health, relationships, knowledge). Shrink liabilities (dependencies, waste, bad habits).

Before each release: "Does this grow an asset or grow a liability?"

Principle 8: KPI = Yesterday's You

Personal progress over peer comparison.

When building any ranking or score feature, always add the personal-best axis alongside the leaderboard:

// ✅ Compare to personal best, not others

final personalBest = await fetchPersonalBest(userId);

final improvement = currentScore - personalBest;

Principle 9: Goal = IPO / Wellbeing

Long-term happiness over short-term KPI racing.

Monthly DAU and conversion rates matter, but the real question is: "Will this service still add value to the user's life in 5 years?"

The Checklist

7+ ✅ → build it


4–6 ✅ → redesign


3 or fewer → skip or major rethink

Real Decisions This Framework Made

The Key Insight

What a solo developer can compete on against 21 well-funded companies isn't features, pricing, or even code quality — it's philosophy.

These 9 principles are "what to build." The AI development 7 principles I covered previously are "how to build it."

Only features that pass both frameworks get implemented. The constraint prevents drift toward becoming a pale copy of the competitors.

Building in public: https://my-web-app-b67f4.web.app/

buildinpublic #FlutterWeb #AI #solodev #productphilosophy