Choose your path

Yes — all tiers require you to bring your own LLM provider API key. Socrates works with OpenAI (GPT-4o, GPT-4o-mini), Anthropic (Claude 3.5 Sonnet, Claude 3 Opus), and any OpenAI-compatible endpoint (Together.ai, Groq, DeepSeek, vLLM, Ollama). You pay the provider directly for model usage; we never charge for inference. The free tier supports 1 key; premium tiers allow more.

Diophantus (free) gives you up to 5 saved sessions, 1 LLM provider key, standard teaching quality, a basic knowledge graph, and community support. All core features — LaTeX rendering, real-time streaming, diagnostic questions, the mistake book — are included. No credit card needed. Just bring your API key and start learning.

Yes. Annual billing saves approximately 17% — effectively 2 months free. Riemann is $90/year (vs $108), Descartes is $190/year (vs $228), Euclid is $390/year (vs $468). You can choose monthly or annual during checkout. Annual plans can be cancelled anytime with pro-rated refunds.

Absolutely. Subscriptions are month-to-month with no long-term commitment. Upgrade instantly from your profile settings — the new features unlock immediately. Cancel any time; your access continues through the end of the billing period. Downgrades take effect at the next billing cycle.

Euclid is our premium tier for power users and teams. Key differences: unlimited saved sessions vs 200, unlimited LLM provider keys vs 5, maximum teaching depth with full customization of the Socratic style, knowledge graph export (JSON/CSV), priority support with faster response times, and early access to new features before they ship to other tiers.

We don't offer refunds for partial months, but every subscription includes a 7-day free trial of the next tier up — so you can try before you commit. If you cancel during the trial period you won't be charged. Annual plans cancelled early may receive a pro-rated refund for remaining months.

Not yet, but we're working on it. If you're interested in team accounts, centralized billing, or managed deployments for your organization, email us at hello@topodrive.top and we'll keep you updated.

Currently we don't have a formal student discount program, but the free Diophantus tier includes all core teaching features. Many students use the free tier successfully with their own low-cost API keys. Email us at hello@topodrive.top if you have specific needs — we're flexible.