> ## Documentation Index
> Fetch the complete documentation index at: https://tanso.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> What Tanso is and who it's for

**Tanso** is an open-source monetization engine for B2B AI products — built
for teams that sell credits or usage and whose inference costs are big enough
that margin per customer is a real question.

Every metered event carries its cost: input/output tokens, model, provider,
and what that usage cost you — alongside what you billed for it. Billing tools
meter usage but don't know your costs; observability tools know your costs but
don't bill. Tanso does both in one ledger, so you can see margin per customer,
per feature, per model.

The same ledger enforces in real time: entitlement checks, usage caps, and
credit limits are applied when the event is ingested, not reconciled at
invoice time. Billing state lives in Tanso — Stripe is the payment adapter,
not the source of truth.

## The model

You define your pricing once, and everything else derives from it:

| Object           | What it is                                                                                             |
| ---------------- | ------------------------------------------------------------------------------------------------------ |
| **Feature**      | A single capability you sell — `api-calls`, `seats`, `export`                                          |
| **Plan**         | A bundle of features with a base price and billing interval                                            |
| **Rule**         | How a feature behaves in a plan: flat, usage-based, or graduated pricing, plus optional credit backing |
| **Customer**     | Your customer, keyed by *your* ID (`customerReferenceId`) — no ID sync                                 |
| **Subscription** | A customer on a plan, with period tracking and proration                                               |
| **Event**        | One unit of usage, idempotent, carrying units, cost, and revenue                                       |
| **Entitlement**  | The materialized answer to "can this customer use this feature right now?"                             |
| **Credit pool**  | Prepaid balance with grants, FIFO draw-down, expiry, and an append-only transaction ledger             |

## The integration loop

Three calls from your backend:

1. **Check** an entitlement before serving a request.
2. **Serve** the request.
3. **Report** a usage event after.

Tanso enforces limits at ingestion, rolls usage into invoices at cycle close,
syncs Stripe when connected, and computes margin from the costs you stamp on
events.

## Next steps

* [Quickstart](/quickstart) — running with seeded data in about five minutes
* [Billing lifecycle](/billing-lifecycle) — from empty database to first revenue, every call spelled out
* [Self-hosting](/self-hosting) — configuration and production notes