All free resources

The 3·7·9 System: From Idea to Paid App

The whole route from idea to income, on one page. Three ways to build an app with vibe coding, seven ways to get paid, and nine ways to prove people actually want it. No coding background needed.

Prompt language

Between an idea and someone paying for it there are only three jobs: build it, get paid, and make sure people want it. Most people don't get stuck because they can't code — they get stuck because they don't know what to do next. This page breaks the three jobs apart, with concrete moves for each.

🛠️ 3 Ways to Vibe Code — Build It

You don't have to write code from scratch. These three get the app built:

  1. 1Design first

    Generate the interface with Figma Make or Google Stitch. Screens first, features second.

  2. 2Code by conversation

    Ask for what you want in everyday language. When it breaks, paste the error message straight back to the AI.

  3. 3Let MCP do it

    Ship, add sign-in and take payments in a sentence, instead of clicking through every dashboard.

When something breaks, paste this to the AI:

Prompt 1 — Fix the error
Here is the error message. Please explain what caused it and fix it.

(Paste the full error message)

💰 7 Ways to Monetise — Get Paid

Building it isn't the same as earning from it. These are the seven most common ways to charge:

  1. 1Onboarding

    A questionnaire first, then the paywall. The questions make users feel the app was made for them.

  2. 2Hard paywall + 3-day free trial

    No payment, no access — but they can try it for three days first.

  3. 3Soft paywall

    Core features free, advanced features paid.

  4. 4Subscription or one-off purchase

    Weekly, monthly or yearly plans, or a single lifetime purchase.

  5. 5Usage-based pricing

    Charge in credits — pay for what you use.

  6. 6UGC ads

    Short videos in a user-made style that drive downloads.

  7. 7SEO / AEO / GEO

    Get found on Google and in AI search.

You don't need all seven. Pick one or two that fit your app and test those first.

🔎 9 Ways to Validate — Prove People Want It

Before you build, use these nine to check someone will actually pay:

  1. 1Read competitors' 1–3 star reviews

    Bad reviews are a free feature list.

  2. 2Collect complaints on Reddit

    Find users' real pain points and the words they use for them.

  3. 3Check similar apps’ public revenue on X

    See what apps like yours actually earn.

  4. 4Three questions for picking a topic

    What are you good at? Is the audience big enough? What do competitors get criticised for?

  5. 5SEO / AEO

    How do users search for this problem?

  6. 6Ad libraries

    Are competitors running ads consistently? Long-running ads mean the market pays.

  7. 7Crunchbase funding records

    Are investors betting on this space?

  8. 8PostHog user data

    Where do users drop off?

  9. 9Pre-sell with a Stripe payment link

    Confirm people will pay before writing a line of code.

The first one is the quickest to start with. Paste this into Claude or ChatGPT:

Prompt 2 — Summarise the bad reviews
Summarise the one- to three-star App Store reviews for [your app type] and list the ten most common complaints.

3 ways to build, 7 ways to charge, 9 ways to validate — that is the whole route from idea to income. Prove people want it, then build it, then charge for it. Get the order right and nothing you build goes to waste.

📱 Next step · Online course

Build your app with AI, from the App Store to your first 10 users.

This prompt finds a problem worth solving. The course takes you the rest of the way, without quitting your job: build the app with AI, ship it to the App Store and Google Play, and get it into real users' hands.

  • Zero coding: you describe it, AI builds it
  • iPhone + Android, submitted to both stores
  • Find your first 10 users, then charge
  • 7 modules · ~7 hours · Cantonese · starts 30 Nov
See the course120+ purchased
Free community

Get the next prompt before it’s public

New prompts, practical techniques and workshop news go to the WhatsApp community first. Free to join, and you can leave any time.

Join Hong Kong parents and professionals learning AI together.

Join the WhatsApp community
Applied AI Academy app — free AI level assessment onboarding screen
Want to know more?

Take it further in the app.

These prompts are a free starting point. Our 30-day AI challenge app turns them into a guided daily practice you can fit into about 10 minutes a day — built for working professionals.