---
title: Tanso Core, the open-source engine behind agent-ready products
description: Metering, credits, entitlements, subscriptions, and Stripe billing in one ledger, plus an agent-serve surface with machine-readable pricing, programmatic signup, scoped keys, off-session payments, and a burndown API. AGPL-3.0, self-hosted.
date: 2026-08-15
---

# Tanso Core

One ledger for what was used, what it cost, and what you billed.

Tanso deploys beside your existing stack and gives your product a surface
your customers' agents can use. Readable pricing, one-call signup, scoped
keys, and payments under spend caps. Behind it sits a full engine (metering,
credits, entitlements, subscriptions) you can adopt as much or as little of
as you want. Open source under AGPL-3.0, self-hosted, no paid tier.

## Adoption path

Additive, not a migration.

1. **Open the agent lane.** Deploy Tanso beside your stack. Agents get
   machine-readable pricing, signup, keys, and credit top-ups. Your human
   checkout and existing billing are untouched.
2. **Meter for margin.** Optionally send your AI usage events through Tanso.
   Cost lands next to revenue in one ledger, and you see margin per
   customer, feature, and model.
3. **Make it the record.** If it earns it, let Tanso run plans,
   entitlements, and invoicing for everyone. Each step is optional; none is
   the price of entry.

## The engine

One ledger for what was used, what it cost, and what you billed.

- **Metering.** Idempotent usage events that carry tokens, model, provider,
  and cost next to what was billed. Costs and revenue land in one ledger, so
  margin per customer, per feature, and per model falls out of the same
  system that bills.
- **Entitlements.** Real-time allow or deny in your request path. Usage caps
  and credit limits apply when events are ingested, not at invoice time.
  Checks fail closed. No active subscription or empty pool means deny.
- **Credits.** A standalone credit wallet with pools, grants with expiry and
  rollover, FIFO draw-down, and a full append-only ledger. An empty pool
  declines the action before you incur the cost of serving it.
- **Subscriptions and billing.** Plans, proration, invoices, and cycle
  rollover for the customers Tanso serves. Stripe is the optional payment
  adapter. Your existing billing keeps running; nothing has to migrate.

## Agent-serve

Everything an AI agent needs to discover, buy, and use your product without
a human touching a browser. All of it opt-in per account and off by default.

- **Machine-readable pricing.** Your plans, features, and credit weights
  published as a public catalog agents can read without a session.
- **Programmatic signup.** One API call creates a customer, subscribes your
  free plan, and returns a customer-scoped key. No captcha, no email loop.
- **Scoped keys.** Customer-scoped credentials pinned to one customer with
  read and purchase scopes. Everything else denies by default.
- **Payments without a browser.** Saved payment methods charge off-session.
  No card on file returns 402 with a checkout link the agent can hand to its
  principal and poll.
- **Spend caps and consent.** Every agent-initiated charge is checked
  against your cap before money moves, and spend tools require explicit
  confirmation.
- **Burndown API.** Per-feature usage projections and credit depletion
  dates, so an agent can answer "when do I run out" before it commits.

## Pricing control

Two levers, no deploys. How many credits an action burns is the weight
table. What a credit costs is the price book. Both are versioned,
effective-dated, and editable from the console, and every check and charge
picks up the new rate at its effective time. Past usage is never repriced.

## Links

- [Source (AGPL-3.0)](https://github.com/tansohq/tanso-oss)
- [Documentation](https://tanso.mintlify.app)
- [Agent-serve docs](https://tanso.mintlify.app/agent-serve)
- [HTML version of this page](https://tansohq.com/product)

More for agents: https://tansohq.com/llms.txt