---
title: "Buy a credit pack by card; returns a Stripe payment page URL"
method: POST
path: "/v1/backtest/checkout"
tags: ["backtest", "purchase"]
---

# Buy a credit pack by card; returns a Stripe payment page URL

`POST /v1/backtest/checkout`

## Request

- Base URL: `https://outcometick.com`
- URL: `https://outcometick.com/v1/backtest/checkout`
- Auth: none required

Spends money or credits. An agent must show the quote to the user and get explicit approval before calling this. Pass key to add the credits to an existing backtest key.

## Request body

- object
  - `pack` string, required: Pack id from /v1/backtest/packs
  - `locale` 'en' | 'zh': Decides the currency (zh pays in CNY) and the return page
  - `key` string: Existing backtest key to top up

## Response `200`

OK

- object
  - `url` string, uri
  - `session_id` string

## Other responses

- `401`: Backtest key not valid
- `404`: Unknown pack
- `409`: Account cannot be topped up here
- `429`: Rate limited; retry after the Retry-After header
- `503`: Temporarily unavailable; retry

---

[API](https://skmtc.dev/outcometick/apis/outcometick-api.md) · [All operations](https://skmtc.dev/outcometick/apis/outcometick-api/llms.txt) · [OpenAPI document](https://skmtc.dev/outcometick/apis/outcometick-api/revisions/d62d9e463bbf?raw)