Frequently asked questions

Quick answers to the questions we hear most often. For detailed walkthroughs, explore the guides in the sidebar.

What types of schools can use C3NTR?

Any school that teaches a structured body of knowledge, with or without grades. C3NTR ships with ten discipline categories — Martial Arts, Dance, Music, Yoga, Gymnastics, Fitness, Performing Arts, Academic, Wellness, and Creative — and 80 sub-disciplines as starting points. None of these are limits; your school can be configured however suits you. See Disciplines for the full list.

Is C3NTR free?

Yes. The Seed plan is free forever and includes all core features for up to 30 members — articles, glossary terms, tags, video and audio, search, favourites, and branding. Paid plans (School and Academy) add AI writing, engagement analytics, higher member limits, and more storage. See Billing & tiers for details.

Does C3NTR use AI?

C3NTR has two AI features, both optional:

• AI writing assistant — Generates article drafts using Claude or ChatGPT. You supply your own API key, which is stored only on your device and never sent to C3NTR. See AI writing assistant.
• On-device search — Uses a small language model (MiniLM) running entirely on your phone to understand the meaning of your search queries. No data leaves your device. See Search.

Is my AI API key stored on your servers?

No. Your API key is stored in your device's secure storage only. It is never sent to C3NTR servers, saved in any database, or accessible to anyone else. When you use the AI draft feature, the request goes directly from your device to the AI provider (Anthropic or OpenAI) through our Cloud Function, which passes the key through without storing it.

Can students see draft content?

No. Draft articles and terms are visible only to members with a content-editing role (instructor or above). Students never see content until a teacher or school leader publishes it. See The editor for how publishing works.

How do grades restrict content?

Each article or term can have a minimum grade level. Members below that grade will not see the content in their Explore tab, search results, or favourites. This lets you release material progressively as students advance. See Roles & grades.

Can I use C3NTR for non-martial-arts schools?

Yes. C3NTR was originally built for martial arts, but it works for any school with structured knowledge. Dance studios, music academies, yoga schools, gymnastics clubs, and academic tutoring centres all use it. The discipline system adapts templates and AI context to your field.

What happens when I go offline?

Articles you have already opened are cached on your device and can be read without internet. Search falls back to keyword-only mode. A banner shows when you are offline, and a snackbar appears when connectivity returns. See Offline access.

Where did my Favourites tab go?

The Favourites tab is now the Library tab. Your saved items are still there, as one section inside the Library — alongside Continue Reading (articles you've started but haven't finished) and Recently Viewed. Nothing was deleted. If your school has renamed the tab, look for the open-book icon in the fourth slot of the navigation bar. See Library.

Why are my favourites split into Articles, Terms, Videos, Audio, and Tags?

The Favourites strip in the Library now groups what you've saved by kind. A pill row at the top lets you switch between the five buckets. Empty buckets stay hidden, so the row only shows the kinds of things you've actually hearted. You don't need to choose a bucket — C3NTR puts each new favourite in the right place automatically. See Library.

Can I publish a video or audio recording on its own?

Yes. On the Explore tab, tap the + button in the top-right and choose Video or Audio. The file picker opens straight away, and you can add a title, description, credit, cover image or artwork, tags, and permissions — same shelf as articles and terms. Standalone videos and audio show up on the Videos and Audio landings in Explore, can be hearted into the Library, and have their own view count. See Images, video & audio.

Is there a per-file size limit for video or audio?

No. There's no per-file cap on any tier — a single recording can use as much of your storage quota as you want. The only constraint is your school's total storage (500 MB on Seed, 5 GB on School, 10 GB on Academy). Check usage at any time in Settings > Storage & Cache. See Billing & tiers.

Can I limit who sees a term, video, or audio recording?

Yes. Open the item in its editor and tap Permissions in the title menu. You can set a minimum grade level, restrict to specific roles, or leave it open to everyone. The icon next to the menu label shows the current state, and locked items get a small lock badge on their card so school leaders can spot what's hidden at a glance. The same options that have always worked on articles now apply to terms, videos, and audio. See Edit modes.

How do I switch between schools?

If you belong to more than one school, tap your school name at the top of the home screen to open the school selector. Choose a different school to switch. Your profile is shared, but content and favourites are separate per school.

What is the difference between tags and sections?

Tags replaced sections in a recent update. Tags are a more flexible way to organise content — an article can belong to more than one tag. If you see "sections" mentioned anywhere, it refers to the old system. Everything now uses tags. See Tags & organisation.

Where did the tag list go in the Explore menu?

The book menu in the top-right now holds just content types and sort. To browse by tag, use the tag cards at the top of each landing — tap a card to open that tag's page, or long-press it for quick actions like Favourite (and, for school leaders, Edit and Delete). See Explore tab.

Can I import my existing curriculum?

Yes. C3NTR supports importing from Word documents (.docx), PDF files, Markdown (.md), plain text (.txt), and rich text (.rtf). You can also share web pages directly from Safari or any browser. Use the share sheet from any app and choose "Import to C3NTR", or pick a file from within the app. The Document Map screen shows you how the content will be split into articles before you confirm. See Import a document.

How does the AI draft feature work?

You enter a topic and optional bullet points. C3NTR sends this to your chosen AI provider (Claude Haiku or GPT-4o mini) along with your school's discipline for context. The AI returns a Markdown draft that appears in the editor. You can undo it instantly or edit it like any other content. See AI writing assistant.

How does on-device search work?

C3NTR includes a small AI model (MiniLM-L6-v2, about 22 MB) that runs directly on your phone. When you search, it compares the meaning of your query with the meaning of each article, not word-for-word matches. This means searching for "blocking techniques" can find an article called "Defensive postures" even though the words are different. All processing happens on your device. See Search.

Is there a web version?

Yes. School leaders and teachers can manage content, members, and settings from a computer. Link an email to your account first. See Your profile.

How do I invite members to my school?

Go to your member management screen and add phone numbers individually or in bulk. Members receive a text or can enter your school's join code in the app. You approve each pending member before they gain access. See Members.

Can I customise how my school looks?

Yes. The Theme Studio lets you set your brand colour, choose dark or light mode, upload your logo and hero image, and adjust surface depth. Changes apply immediately for all members. See Branding & theme.

What are templates?

Templates are pre-written collections of articles, terms, videos, and audio for specific disciplines, organised across ten categories. You can import any template into your school and edit the content freely. You can also save your own documents as templates. See Templates.

Can I add general school info that isn't tied to a discipline?

Yes. Tap the For any school pill in the template library for two families that work for any school: Teaching toolkits (how you teach — building a practice habit, a new student's first month) and School essentials (a welcome handbook, a code of conduct, attendance and policies). They add on top of what you already have, and importing the same pack twice won't create duplicates. See Templates.

Can I publish imported content straight away?

Yes. When you import a template, choose Publish now to make the content visible immediately, or Drafts to review and publish it later from the Explore editor. See Templates.

Can a template set my school's colours?

If you like a template's look, tick apply this template's colour & hero image when you import it — C3NTR copies the brand colour and hero image to your school. You can change them anytime in Branding.

How do I request a template?

If we don't have your discipline yet, open the template library, tap the filter control (or the empty-results screen), and choose Request a template. Tell us what would help and it goes straight to our team. See Templates.

Can I change my phone number?

Yes. Go to Edit Profile and tap "Change phone number". You will verify the new number with an OTP code, and it replaces your old number immediately. See Your profile.

Can I delete my account?

Yes. Go to Edit Profile, scroll to the bottom, and tap "Delete account". You will be asked to type DELETE to confirm. This permanently removes your profile, favourites, memberships, uploaded files, and sign-in credentials. It cannot be undone. See Your profile.

How is my data stored?

Your school's data is stored securely on Google Cloud (Firebase) in the europe-west2 region. Data is encrypted at rest and in transit. We do not sell or share your data with third parties. For full details, see our Privacy Policy.

How do I open the user menu?

Two ways: tap your avatar in the top-right of the Home screen, or swipe in from the right edge of any tab. The avatar shows your profile photo if you have one, or your initials over your school's primary colour. See Your profile.

How do I send feedback or suggest an idea?

Open the user menu and tap Send feedback in the "Feedback & roadmap" card. Pick "Something's off" to report an issue or "I've got an idea" to suggest a feature, answer one or two short questions, and optionally add up to three screenshots. Your submission goes straight to the C3NTR team by email. You can also tap View the roadmap in the same card to see what we're working on next.

How do I contact support?

For most questions, the in-app feedback form is the fastest way — see above. For account-specific issues, email us at hello@c3ntr.app. We aim to respond within 24 hours.