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I build apps, and help other developers make money from theirs.

Hi, I'm Perttu Lähteenlahti, a developer and designer in Finland. I'm a Senior Developer Advocate at RevenueCat, run the software studio Fenrir Digital, and have won 40+ hackathons along the way. More about me, or what I'm up to now.

Get in touchRead the guides
Perttu on stage at Chain React

Chain React 2026

Perttu on a couch on stage at App.js Conf, holding a microphone

App.js 2026

Perttu ice fishing on a frozen sea

Arctic Conf 2026

Perttu handing out a plush toy at the RevenueCat booth

Droidcon London

Perttu speaking on stage at React Conf

React Conf 2025

Perttu presenting against a blue backdrop at App.js Conf

App.js 2026

Drag the photos around, or deal a new hand:

Articles & Tutorials

Practical guides on React Native, iOS and app monetization, mostly from problems I've hit shipping my own apps. I also write for the RevenueCat blog.

Cover image for How not to ship slop

How not to ship slop

AI is useful, but it will happily help you ship average work with a finished-looking surface — here is how to keep it from setting your bar.

Cover image for App.js 2026 recap

App.js 2026 recap

A recap of App.js 2026 with a sponsor's, speaker's, and participant's perspective.

Recent Talks

  1. Why React Native apps monetize better

    next.app devCon Berlin, October 2026

  2. Making React Native apps first-class citizens in iOS with App Intents

    Chain React, July 2026

  3. Monetize your Android app the right way

    Droidcon Orlando, July 2026

See all talks

Work

  1. RevenueCat logo
    Company
    RevenueCat
    Role
    Senior Developer Advocate
    Date
  2. Fenrir Digital logo
    Company
    Fenrir Digital
    Role
    Founder
    Date
  3. Noice logo
    Company
    Noice
    Role
    Senior Mobile Developer
    Date
  4. Veri logo
    Company
    Veri
    Role
    Product Lead
    Date
  5. Mavericks logo
    Company
    Mavericks
    Role
    Senior Software Engineer
    Date
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