Optional. The trainer works fully without this. Add your own Anthropic API key to unlock free-form Socratic Q&A inside each module.
Your key is used only for direct browser calls to Anthropic and is never sent anywhere else. In a standalone file it stays on this device. Calls use your account and incur usage costs.
Get one at console.anthropic.com → API Keys. How to get a free key →
Any model your key can access. Sonnet is a good default for tutoring.
Activate the live AI tutor
The lessons, practice quizzes, and exam all work without this. The AI tutor only adds free-form Q&A, and it needs your own Anthropic API key.
There is no permanent free API tier. A new developer account gets a one-time ~$5 trial credit (phone verification, no credit card). That is enough to run this tutor for a while — especially on the cheaper Haiku model — and once it is gone you would add prepaid credits to keep going.
Create a developer account at console.anthropic.com. This is separate from a Claude.ai chat subscription, even if you reuse the same login.
Verify your phone to claim the trial credit, then check Plans & Billing for the balance. Use a real mobile number — VoIP / Google Voice numbers are rejected.
Create the key under Settings → API Keys → Create Key, then copy it immediately — it is shown only once. It starts with sk-ant-.
Paste it into ⚙ Settings in this trainer and press Save.
To stretch the free credit, set the model to claude-haiku-4-5-20251001 — much cheaper than Sonnet and plenty for tutoring.
With only trial credit and no card on file you cannot be over-charged: when the credit runs out, the AI calls simply stop. Your key stays in this browser, and you can revoke it anytime in the console.