Music Theory by Justin Guitar

Musopia

In-app purchases

About this app

Now launching in Early Access! Start your journey today with special early pricing while we add more content and features. Get in at the beginning and grow with us!

Tired of music theory lessons that feel boring or disconnected from real playing? This is the ultimate music theory app for guitar players who want to unlock the fretboard and make sense of the music they love. With the Music Theory by Justin Guitar app, you’ll finally understand how music works — and apply it immediately to level up your guitar playing.
Unlike traditional courses, this app combines bite-sized guitar lessons with interactive fretboard exercises. No endless theory talk — just practical learning that connects directly to how to play guitar. Whether you play acoustic or electric guitar, Justin’s proven approach makes theory useful, fun, and motivating.
🔥 Why It Works for Guitarists
• Learn how to play guitar with scales, chords, and progressions that make sense
• See a pattern, play it instantly, and remember it forever
• Connect keys, notes, and intervals directly to the guitar fretboard
• Skip the textbooks and focus on guitar lessons that stick
🎯 What You’ll Accomplish
• Stop feeling lost when people talk about keys, scales, and chord progressions
• Learn songs by ear instead of relying only on tabs or chords
• Memorize every note on the fretboard with the fretboard trainer
• Recognize hidden chord and note patterns in the music you love
• Jam with confidence instead of just following along
• Write your own riffs and solos using solid music theory knowledge
• Break through frustrating plateaus with a clear roadmap
• Accelerate your progress by learning the language of music

🎸 Built for Guitar Players
Every lesson happens on the guitar fretboard. You’ll explore fretboard navigation system (think CAGED, but better), barre chords, scales, ear training, chord progressions, and note patterns in a way that’s 100% relevant to guitarists.

⚡ Interactive Learning That Sticks
• Quick lessons, quizzes, and exercises that build step by step
• Fretboard and chord trainers with instant feedback
• Practical ear training and recognition drills (coming soon)
• Mobile learning at your own pace
• Apply every concept immediately to your favorite songs

👨‍🏫 From the Teacher Millions Trust
Justin Sandercoe — the teacher behind JustinGuitar and Justin Guitar lessons — has taught millions of players worldwide. His clear, encouraging teaching style has made Justin Mobile apps the go-to tools for guitarists of every level.
Whether you’re picking up a guitar for the first time, stuck on a plateau, or ready to finally master theory, this app will give you the music theory foundation every guitarist needs.

✅ Download Music Theory by JustinGuitar today and turn music theory into your guitar superpower!

We’d love to hear your feedback - email us at [e-mail]

*The lowest requirements for using the app on the Android device
is Android 15 (API level 35) or higher



Important subscription information

Justin Guitar offers several FULL ACCESS subscription packages that unlock unlimited access to all the published stages.

Subscription purchases are charged to your Google Play account upon confirmation of the purchase. All subscriptions will AUTOMATICALLY be renewed unless the auto-renew is turned off at least 24 hours prior to the end of the current period. Your Google Play account will be charged a normal subscription price of the original subscription within 24 hours prior to the end of the current period.

You can manage your subscriptions and turn off auto-renew by going to your Account Settings after the purchase. Subscriptions are non-refundable and may not be cancelled during an active subscription period.

Our privacy policy can be found at https://www.musopia.net/privacy/
Terms of use: https://musopia.net/terms

Ratings and reviews

this is a really fun app to learn music theory. The lessons are small bite size and give you exercises to practice while you are watching the video. also, at the end of each module you have 3 exercises to practice what you have learned. another great thing, is that you can repeat each lesson as many times you need to memorize the theory. I am so glad and happy to buy this. well invested money and I would definitely recommend it to anyone who wants to learn music theory in a fun and practical wa

Pay wall, no trial

Just the first few lessons and things are starting to click. I'm terrible at memorization and was having the worst time with remembering where note placement was on the fretboard. Now I can see a pattern. Can't wait to learn more! Thank you Justin.

What’s new

New Lessons 1–4 in Unit 3
Start exploring the next chapter of your theory progression with four new lessons packed with essential concepts.

Brand-new exercises in Unit 2
Continue building your skills with fresh practice material designed to deepen your understanding.

Improved exercises in Unit 1
Early-unit exercises have been polished for clarity, smoother interaction, and a better overall learning experience.