---
title: "The machine-readable rate card (the billing contract)"
method: GET
path: "/api/tariff"
---

# The machine-readable rate card (the billing contract)

`GET /api/tariff`

## Request

- Base URL: `https://api.signalbureau.ai`
- URL: `https://api.signalbureau.ai/api/tariff`
- Auth: none declared

Public tariff: units (Watch, Read), flat opening rates, the free allowance on a self-issued key (25 asks per key for the life of the key since 2026-09-05 — not per day; `before` states the per-day terms keys issued earlier keep), the money-back guarantee, and the free-key issuance path. The code that enforces allowances reads the SAME object this endpoint serves, so the stated allowance is the enforced allowance by construction. A dated decision history records every rate change.

## Response `200`

The tariff object.

- object
  - `currency` string
  - `units` object[]
    - `unit` string
    - `price` number
    - `free_daily_allowance` number: Keyless Answer Engine answers per day per network address (25/day anonymous, with no key, since 2026-10-06, revision keyless-daily-allowance; it was 0 from 2026-08-08 under universal keying). Resets at midnight UTC. A key's own meter is `free_key_allowance`.
    - `free_key_allowance` object: The free allowance on a self-issued key (Read unit), LIFETIME not daily since 2026-09-05: {asks, per: 'key', resets: 'never', effective, note, daily_ceiling, daily_ceiling_note, before: {per_day, resets, note}} — `before` states the per-day terms keys issued earlier keep. Replaced free_key_daily_allowance (schema_version 1 -> 2). The sibling `balance` object on the same unit states the top-up terms: {min_usd, max_usd, per: 'key', drawn_at: 'read' (the rate is the Read price above, by reference), expires: 'never', order, refundable, refund_path}.
  - `guarantee` object
  - `free_key_how` string

---

[API](https://skmtc.dev/sigb/apis/signal-bureau-api.md) · [All operations](https://skmtc.dev/sigb/apis/signal-bureau-api/llms.txt) · [OpenAPI document](https://skmtc.dev/sigb/apis/signal-bureau-api/revisions/290c9c6ca0d0?raw)