# Sinth

> Sinth is an uncensored AI communication platform. Its current self-service API provides prepaid starter chat. Public base URL: https://sinth.ai

## Documentation
- [Full API guide](https://sinth.ai/llms-full.txt): Onboarding, examples, limitations and the complete OpenAPI contract in one text file.
- [API overview](https://sinth.ai/docs): Onboarding, authentication, pricing and supported scope.
- [OpenAPI](https://sinth.ai/openapi.sinth.yaml): Machine-readable production endpoint contracts.
- [Quickstart](https://sinth.ai/start): First chat request and balance check.
- [Pricing](https://sinth.ai/pricing): Purchase prepaid credits through Stripe; payment brand is Scions Tech.

## New customer workflow
1. POST https://sinth.ai/api/stripe/checkout with JSON {"bundle":"start"} for $10, or {"amount_cents":1000} (integer, 1000–500000).
2. Open the returned complete URL and complete Stripe-hosted payment. This API creates a checkout; it does not itself charge a card.
3. The API key arrives at the purchase email after successful payment. An agent needs inbox access or its owner to supply the key. No key is returned by checkout creation.
4. GET https://sinth.ai/api/v1/usage with Authorization: Bearer YOUR_SINTH_KEY.
5. POST https://sinth.ai/api/v1/chat with that header and JSON {"message":"What is two plus two?","end_user":"my-user-1"}.
6. Expect reply, cost_cents: 2 and balance_cents. Verify balance with the usage endpoint.

## Integration limits
Store credentials server-side. Keep end_user stable per application user; histories are scoped by the customer's key and end_user. Omit persona_id for the supported starter assistant. There is no OpenAI-compatible interface, streaming, model-selection or tool-calling contract. Broader backend management APIs require separate provisioning and are not available through a purchased Sinth key. Public demos are separate from paid API calls.

Production uses real payments. Sandbox keys and credits work only in their isolated test environment. A failed chat response with refunded: true has returned its debit. Successful requests are individually billed; there is no inference idempotency-key contract. A lost-response timeout is not proof that no charge occurred.