learnFORTH
Learn Forth the easy way, OK?
Free · In-App Purchases · Designed for iPad. Not verified for macOS.
Is your brain melted? No? Maybe you want to change that, and if so, learning Forth can be the best way to achieve it.
It's time to learn Forth, the compact stack-based language that powered navigation computers, embedded systems, and a generation of hands-on hackers - and still runs the boot firmware on some retro Sun and Apple hardware. If you ever saw a Jupiter ACE home computer, now is your change to learn about what made it special.
This app teaches you to think in words and stacks with 90 short, structured daily lessons, a live REPL you can experiment in right on your phone or iPad, and hands-on exercises with hints (not answers) so you actually learn the ideas.
WHAT'S INSIDE
• 90 guided lessons across 7 topics: the data stack, words & variables, control flow, loops & recursion, advanced words, data structures, and advanced topics.
• A built-in REPL with syntax highlighting so you can type real FORTH and see the stack respond immediately.
• Exercises for every lesson, graded on output, with an optional hint if you get stuck.
• Daily streaks and per-category progress tracking to keep you moving. You'll learn, promise!
• A plain-English primer on Reverse Polish Notation and stack manipulation (DUP, DROP, SWAP, OVER, ROT) for complete beginners.
• Historical notes on FORTH's dialects - fig-FORTH, Forth-79, Forth-83, ANS Forth - and which one this app's interpreter follows.
• A tip-of-the-hat to the Jupiter ACE, the British home computer from the 1980s that was based on Forth.
• A recommended reading list of classic FORTH books, including Starting FORTH and Thinking Forth by Leo Brodie.
• Light, dark, and automatic themes.
No prior programming experience required. If you've ever wondered how a language with almost no syntax can still get real work done, learnFORTH will show you, one word at a time.
Note: This app is free, with all features always available. If you enjoy it, please use the tip feature to thank the author and encourage future development.
Ratings & Reviews
- This app has not received enough ratings or reviews to display an overview.
Edited some lessons to be clearer.
Added more example programs.
Created a list of default Forth words and their definitions.
The developer, John Kennedy, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Size
- 1.9 MB
- Category
- Education
- Compatibility
Requires iOS 18.6 or later.
- iPhone
Requires iOS 18.6 or later. - iPad
Requires iPadOS 18.6 or later. - Mac
Requires macOS 15.6 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 2.6 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Buy Me a Coffee 9,00 kr
- Provider
John Kennedy
- John Kennedy has not identified itself as a trader for this app. If you are a consumer in the European Economic Area, consumer rights do not apply to agreements between you and the provider.
- Copyright
- © 2026 John Kennedy