# hunta — Marketplace Fee API

> hunta provides a penny-accurate, versioned HTTP API for marketplace fees that platforms don't itemise — starting with the **eBay UK Buyer Protection Fee (BPF)**. Given a price it returns the exact fee, what the buyer pays, and what the seller receives. Forward, inverse and batch. Computed from eBay's published schedule, self-verified against eBay's own worked examples, and version-stamped (`bpf_version`).

For AI agents and developers: the API is machine-first. Base URL `https://api.hunta.io`. Auth via `X-API-Key` header (free key, no card, at https://hunta.io/#pricing). All money is Decimal-exact to 2dp.

## Answer-first
The eBay UK Buyer Protection Fee is `£0.10 flat + 7% (£0–20) + 4% (£20–300) + 2% (£300–4,000) + 0% (>£4,000)` on the item price (postage excluded). It is charged to the **buyer** on UK **private-seller** listings; business sellers and excluded categories (vehicles, classified ads, property) = £0. hunta's API returns this penny-accurate for any price. Current schedule version: `2026-uk-v1`.

## Endpoints
- [GET /v1/fee](https://api.hunta.io/v1/fee): forward — given `item_price` (+ optional `postage`, `quantity`, `seller_type`, `category`), itemise the BPF, buyer displayed total, and seller proceeds.
- [POST /v1/inverse](https://api.hunta.io/v1/inverse): inverse — given the buyer-displayed price, recover the item price + embedded BPF (e.g. "what offer do I send so the buyer pays £250?" → £239.71).
- [POST /v1/batch](https://api.hunta.io/v1/batch): itemise up to 1,000 prices in one call (repricers/analytics).
- [GET /v1/meta](https://api.hunta.io/v1/meta): the live fee schedule, tiers, excluded categories, `bpf_version`, and the freshness-canary status.
- [GET /healthz](https://api.hunta.io/healthz): health check (unauthenticated).

## Docs & pricing
- [API docs](https://hunta.io/docs): full OpenAPI reference (Scalar).
- [OpenAPI spec](https://api.hunta.io/openapi.json): machine-readable spec for client generation.
- [Pricing](https://hunta.io/#pricing): Free ~1,000 calls/mo (no card) · Pro £29/mo ~25,000 + batch · Business £99/mo ~100,000.
- [Free calculators](https://hunta.io/calculator): human fee calculator · [offer calculator](https://hunta.io/offer).

## Trust
- Penny-accurate vs eBay's published worked examples (£5→£0.45, £100→£4.70, £1,500→£36.70).
- A drift canary re-checks eBay's schedule continuously; `bpf_version` bumps on any change.
- Sources: eBay buyer BPF help (id=5594) and seller BPF help (id=5595).