Public API documents
Shopify API reference docs
Square API Reference
Stripe API Reference
mercari shops API reference docs
GitHub REST API documentation - GitHub Docs
sandbox domain
connect.squareupsandbox.com
https://developer.squareup.com/explorer/square/payments-api/create-payment
通常は connect.squareup.com
https://api.mercari-shops.com/docs/index.html#introduction-item-0
https://developer.smarthr.jp/api/about_sandbox