Licences and credits

© 2026 David Willson John Britto (operating MuscleIT). MuscleIT, its logo and app icon, the interface design, the text, the Coach David character, the app screenshots and the two original athlete figures on the home page are our property. All rights reserved. Use of the app and website is governed by our Terms of Service.

The original athlete figures were sculpted by us with our own software and are not taken from any other model. The pictures of the muscle models on the website and in the app are renders of the openly licensed models described below.

The interactive muscle map uses the Écorché model: a derivative work of two openly licensed anatomical datasets, adapted for MuscleIT.

• BodyParts3D 4.0, © The Database Center for Life Science, licensed under CC BY 4.0. dbarchive.biosciencedbc.jp/en/bodyparts3d. Its files still carry the older notice "CC Attribution-Share Alike 2.1 Japan". Sharing our model under CC BY-SA 4.0 meets the conditions of both.
• Z-Anatomy, the libre 3D atlas of anatomy, by Gauthier Kervyn, licensed under CC BY-SA 4.0. It is itself built on BodyParts3D. z-anatomy.com
• BodyExplorer by Johan Bellander published the glTF export of the Z-Anatomy meshes we started from. Its code is MIT-licensed and none of its code is included. github.com/JohanBellander/BodyExplorer

What we changed

• Kept the bones, cartilages, teeth, eyes and skeletal muscles, and left out vessels, nerves, organs, ligaments and skin. Added Z-Anatomy muscles for the back, trunk and head.
• Converted the units and orientation, and reduced the triangle count to make the files small enough for phones.
• Layered overlapping muscles so each lies on the correct side of its neighbour, made the figure symmetrical, and rebuilt the external oblique and serratus anterior as single surfaces.
• Added colour and shading data, and kept each structure's English name. Both a male and a female version are provided.

This is not a medical device. The models are for training and educational purposes only and must not be used for diagnosis or treatment.

Download the model files

• Male model (GLB) and female model (GLB)
• Full attribution and list of changes
• Licence text, CC BY-SA 4.0

The adapted model files are shared under CC BY-SA 4.0. You may copy and adapt them, if you credit the sources above, say what you changed and share your version under the same licence. Licence summaries: creativecommons.org/licenses/by/4.0 and creativecommons.org/licenses/by-sa/4.0. There is no warranty.

All fonts are free and licensed under the SIL Open Font License 1.1 (openfontlicense.org). They are served from our own domain.

• Archivo, © The Archivo Project Authors. The typeface of this website. github.com/Omnibus-Type/Archivo
• Geist and Geist Mono, © Vercel. Used in the app and the admin panel. github.com/vercel/geist-font
• Sora, © The Sora Project Authors. Used for headings in the admin panel. github.com/sora-xor/sora-font

• Lucide icons (ISC licence), which include parts of Feather (MIT). lucide.dev
• Instagram, LinkedIn and X logo shapes come from Simple Icons (CC0, public domain). The logos themselves are trademarks of their owners and are used only to link to our own accounts. simpleicons.org
• Google Play and App Store logos on the "Coming soon" buttons are used to show where the app will be available. They are trademarks of Google LLC and Apple Inc. and are used as their brand guidelines allow.
• The MuscleIT name, wordmark and app icon are our own.

Each project is used under its own licence, and its copyright notices stay with its authors:

• Next.js, MIT. github.com/vercel/next.js
• React and React DOM, MIT. github.com/facebook/react
• Three.js, MIT. github.com/mrdoob/three.js
• React Three Fiber and Drei, MIT. github.com/pmndrs/react-three-fiber
• Zustand, MIT. github.com/pmndrs/zustand
• Tailwind CSS, MIT. github.com/tailwindlabs/tailwindcss
• Better Auth, MIT. github.com/better-auth/better-auth
• Drizzle ORM, Apache-2.0. github.com/drizzle-team/drizzle-orm
• node-postgres (pg), MIT. github.com/brianc/node-postgres
• Lucide icons, ISC. github.com/lucide-icons/lucide
• sharp, used to prepare images, Apache-2.0. github.com/lovell/sharp
• TypeScript, used to build the site, Apache-2.0. github.com/microsoft/TypeScript

The MuscleIT app includes these projects, each under its own licence:

• Next.js, MIT. github.com/vercel/next.js
• React and React DOM, MIT. github.com/facebook/react
• Three.js, MIT. github.com/mrdoob/three.js
• three-mesh-bvh, MIT. github.com/gkjohnson/three-mesh-bvh
• Supabase JS and SSR, MIT. github.com/supabase/supabase-js
• SWR, MIT. github.com/vercel/swr
• Base UI, MIT. github.com/mui/base-ui
• shadcn/ui components, MIT. github.com/shadcn-ui/ui
• Tailwind CSS and tw-animate-css, MIT. github.com/tailwindlabs/tailwindcss
• class-variance-authority, Apache-2.0. github.com/joe-bell/cva
• clsx and tailwind-merge, MIT. github.com/lukeed/clsx
• Lucide icons, ISC. github.com/lucide-icons/lucide
• Razorpay Node SDK, MIT. github.com/razorpay/razorpay-node
• Vercel Web Analytics, MPL-2.0. github.com/vercel/analytics
• SheetJS (xlsx), used to prepare workout data, Apache-2.0. sheetjs.com

The full licence text of every package (MIT, ISC, Apache-2.0 and MPL-2.0) is included with its source code. You can read the standard texts at spdx.org/licenses, or email us and we will send you a copy.

We rely on services run by other companies, described in our Privacy Policy. Their names and logos belong to them and are mentioned only to describe how MuscleIT works. They do not endorse us.

• Google Play and Google Sign-In are trademarks of Google LLC. YouTube is a trademark of Google LLC.
• App Store and iPhone are trademarks of Apple Inc.
• Razorpay is a trademark of Razorpay Software Private Limited.
• Supabase, Vercel, Neon, Resend and GoDaddy are trademarks of their respective owners.

If you believe something on this website or in the app is used without the right permission, or a credit is missing or wrong, email support@muscleit.fit and we will look into it promptly and fix it.