SaaS

Sell an iPhone app that types out WhatsApp voice notes

Build a small iPhone app that turns WhatsApp voice notes into text on the phone itself, so you have no server or AI bills. People who get long voice notes and would rather read them pay for it in the App Store.

The hard part: getting found in a crowded App Store when the app is simple enough for others to copy.

Setup 2 weeksRuns $10/moYour time A weekly check-inNeeds ClaudeVercel

Who pays

People who get long WhatsApp voice notes pay through the App Store to read them instead of listening. The case study reports about $29K a year in revenue at 96% margins, but it does not say how the app charges. A subscription or a one-time unlock after a few free notes is our suggestion, not something the source reports.

How to build it

  1. Set up your Apple developer tools

    Join the Apple Developer Program, which costs $99 a year, and install Xcode on a Mac. Use Claude Code or Cursor to help you write the app in Swift.

  2. Accept voice notes from WhatsApp

    Add a share option so users can tap a voice note in WhatsApp, choose Share, and send it to your app.

  3. Turn speech into text on the phone

    Use Apple's built-in on-device speech recognition or a speech-to-text model that runs on the phone, such as Whisper. That way the audio never goes to a server and you pay no AI bills.

  4. Add a free trial and paywall

    Use App Store in-app purchases, for example through StoreKit or RevenueCat. Let people transcribe a few notes for free, then ask them to subscribe or pay once to unlock the app.

  5. Publish with a simple landing page

    Write an App Store listing with clear screenshots and the words people search for, like "WhatsApp voice note to text." Put up a one-page site on Vercel that links to it.

Sources on X

  • GrowthIndex_ · Aug 5, 2026

    GrowthIndex_ shared a case study of a "boring little iOS utility" that transcribes WhatsApp voice notes. The post claims ~$29K/yr revenue, 96% margins, ~$2,400/mo profit, and zero servers and zero API bills. These are the case study's figures and have not been checked.

Ideas are curated from public posts and untested by us. Read the full note.