Independent dojos
A single sensei, one or two assistants, and a steady group of students. C3NTR puts your kata, terminology and syllabus in one place. No second tool, no spreadsheet.
For martial arts schools
A knowledge home for your karate dojo.
Kata, terminology, kihon and grading, in one place students return to.
→ See a quick tour
Free for up to 30 students
No credit card
UK GDPR · EU (London)
Works offline
Your dojo's curriculum deserves a home
Kata sequences live in one teacher's head, half a binder, and a brown belt's notebook. Japanese terminology gets explained again to every new student from scratch. C3NTR is a quiet place to write it all down once, so students can return to it on their own time.
Who this is for
Schools with multiple instructors
Two or more sensei, several classes a week, the daily work of keeping every class consistent. C3NTR holds the shared standard. Every instructor teaches from the same library.
Growing clubs
You've outgrown the binder. New students arrive every term. Content locked by grade keeps each year appropriate, and senior students help maintain the library as they progress.
Built for teachers, not for IT
Your sensei opens the app, taps Edit, and writes the next kata explanation in plain prose. The next class teaches it. No setup project, no training course.
Write directly in the app
Like a notepad. New articles are drafts until you publish, so nothing goes live by mistake.
Mobile-first authoring
Edit on the phone between classes or on the way home. The same library, the same edit screen.
A working library in under an hour
Import the starter template in a few taps. Edit anything that doesn't fit. Publish when ready.
Kyu and dan grades
Content locked by grade, in your dojo's belts
Tag any article with a minimum kyu or dan. White belts see only what's appropriate for them. Brown belts see brown belt and below. Sensei sees everything. The same library, the right view per student. No one stumbles into next year's kata by accident.
A glossary in Japanese and English
Every dojo has a vocabulary new students learn by hearing it. C3NTR's glossary holds the terms in one place: the kanji or romaji, your school's translation, and the article each term appears in.
- Dojo
- The training hall (道場), literally "the place of the way." More than a gym..
- Sensei
- Your teacher (先生), literally "one who has gone before." In karate the sensei is shown respect for the years of practice they pass on..
- Rei
- The bow (礼), the gesture of respect that opens and closes training..
- Kihon
- The basics (基本), the stances..
- Zenkutsu-dachi
- The front stance (前屈立ち), a long..
- Gyaku-zuki
- The reverse punch (逆突き), a punch with the rear hand from a front stance..
Grading days, competitions, dojo closures
C3NTR isn't only the library. Schedule the gradings students are working toward, post a quick announcement when a class is cancelled, and let students see what's coming up in the dojo this month. Announcements land on their Today tab and events sit on the calendar.
Start from our Karate template
A working starter with fifteen articles spanning stances, kihon, the front kick and roundhouse, your first kata, sparring, the belt system and the dojo kun. Four short videos demonstrate basic technique. Ten Japanese terms sit in the glossary. Import in a few taps, then edit anything that doesn't fit your style. Every article, kata and term is yours from the moment you import.
See the Karate template Template source:assets/templates/martial_arts/karate.c3t.md
Inside the app
A look at how the library, articles and grade controls feel in your students' hands.
Plays well with what you already have
Bring your existing kata syllabus and Japanese terminology in with smart Word document import or paste Markdown directly from your notes.
Word documents
Smart import reads headings and turns them into draft articles. You review before anything publishes.
Markdown from any editor
Notion exports, Obsidian notes, Bear, plain .md files. Paste or import.
C3NTR templates
Open .c3t.md format. Schools can share templates with each other without us in the middle.
UK GDPR · DPA 2018
UK GDPR compliant. Hosted in the EU (London).
C3NTR is built around UK data protection law from the ground up. Your school's data sits in the EU on Google Cloud London, the same region we manage from.
UK GDPR + Data Protection Act 2018
Built around UK GDPR Article 6 lawful bases. Subject access requests answered within one calendar month.
Hosted in the EU (London)
Your school's data sits on Google Cloud in the europe-west2 (London) region. No transfer outside the UK or EEA for core operation.
Encrypted in transit
All data is TLS encrypted. Access restricted to personnel with a clear business need.
Account deletion on request
Permanent deletion of personal data and content via in-app or written request.
What C3NTR is, and what it isn't
A library your school owns
Another booking or billing system
Built for how schools actually teach
A generic course builder
Calm, focused reading for students
A feed competing for attention
Start free. Move up when you outgrow it.
Seed
Free forever
Up to 30 students
All core features. No credit card.
Start freeSchool
£39/mo
£32/mo billed annually
Up to 150 students
Push notifications. 1 GB media storage.
Choose SchoolAcademy
£69/mo
£57/mo billed annually
Unlimited students
Multi-instructor publishing. Engagement analytics. 5 GB media storage.
Choose AcademyStudent? Show this to your sensei.
If you train at a karate dojo and you'd love a quiet library you can return to between classes, share this page with your instructor. Most schools start on the free Seed plan in under five minutes. Your dojo's kata, terminology and syllabus could be in your pocket by next week.
Common questions
Can students only see their belt's material?
Yes. Tag any article with a minimum kyu or dan. White belts see only their own material. Instructors and above always see everything.
Can my school customise the karate template?
Yes. Every article, kata and glossary entry is editable. Add your style's kata list, your dojo kun and your grading standards. The template is a structure, not a script.
Does it cover Shotokan, Goju-ryu, Wado-ryu, Kyokushin?
Yes. The starter works for any style. Shotokan, Goju-ryu, Wado-ryu, Kyokushin and others can adapt the kata list, the syllabus and the etiquette without rewriting from scratch.
How long does it take to set up?
Most schools have a working library in under an hour. Import the starter template in a few taps, then edit anything that doesn't fit. Starting blank takes a little longer. Allow an hour or two to write your first ten articles. Students can use the app the day you publish.
Do I have to stop using my booking system?
No. C3NTR is a knowledge library for your curriculum, terminology and progressions. Booking, billing and scheduling stay with the tools you already use.
Is there a free plan?
Yes. Seed is free forever for up to 30 students, with no credit card required. Move up to School (£39/mo) or Academy (£69/mo) when you outgrow it.
Teach a different style? Tell us.
Whether it's a specific karate lineage we don't list, or another discipline entirely, drop us a line and we'll add a starter template. In the meantime, the app already works for any structured curriculum, your library starts blank in a few minutes.
Ready to give your karate students a knowledge home?
Free for the first 30 students. No credit card. A working library in under an hour.
Start free for your school