Kids' literacy & learning
EVI
EVI helps parents, guardians, teachers, and education professionals create calm, personalized practice stories at AVI reading levels.
- 3 free stories
- No ads
- Live in the App Store
Software with
social impact.
I’m Jolyon Oattes. Under the name graimatter, I build calm, privacy-conscious software that genuinely helps — from managing headaches and finding the right care to helping children enjoy reading. What started as side projects grew into EVI and HeadYogi.
cardiology
Health
Digital solutions that make healthcare more efficient and humane. Personalized care, digitally supported for a better future.
visibility
Accessibility
Software that is clear and easy to use, including when seeing, reading, or navigating takes more effort.
menu_book
Literacy
Tools that promote reading and learning. Educational software that creates opportunities for a smarter and fairer society.
Independent products
One maker story. Two distinct product brands.
Each product has its own audience and landing page. On graimatter, you can read why I built it and the decisions behind it.
Health & self-management
HeadYogi
HeadYogi is a migraine diary you can update in under 10 seconds. Log your headaches, spot patterns—what triggers them, what helps. Your data stays on your phone. No tracking, no ads, no selling your health info to data brokers.
- No account
- Privacy-first
- Live in the App Store
My Approach Pragmatic.
Pragmatic.
Human-centered.
Effective.
I skip the buzzwords. When someone says they need a migraine tracker, I watch how they actually use it—not how I think they should. Most features get cut. The ones that stay? They're there because real people kept asking for them.
01 Discover
02 Design
03 Develop
04 Deploy
Want to know more?
Feel free to reach out for questions or a conversation about technology and social impact.
Contact