Billing & tiers

C3NTR offers three tiers so you can start free and grow at your own pace. Every tier includes the core knowledge library. Paid tiers unlock extra features as your school needs them.

The three tiers

• Seed (free forever) — Up to 30 members, 100 MB storage. All core features included: articles, glossary terms, tags, search, announcements, analytics, and branding.
• School — £39/month, or £32/month billed annually. Up to 150 members, 1 GB storage. Adds video support and the AI writing assistant.
• Academy — £69/month, or £57/month billed annually. Unlimited members, 5 GB storage. Everything in School, with room to grow.

Annual billing saves roughly 18% compared to paying monthly.

Feature gates

Two features require the School tier or above:

• Video support — Upload and embed video in your articles.
• AI writing assistant — Generate article drafts with help from AI.

If you try to use a gated feature on the Seed tier, you will see a prompt to upgrade. No content is lost — the feature becomes available the moment you move to a paid plan.

Upgrade your plan

Manage your subscription

From Settings > Billing, tap Manage subscription to open the Stripe billing portal. There you can:

• Switch between monthly and annual billing.
• Update your payment method.
• View and download invoices.
• Cancel your subscription.

Storage add-ons

If you reach your storage limit on a paid plan, you can purchase additional storage from the billing portal. Storage add-ons are not available on the free Seed tier — upgrade to School or Academy first.