Environments

	🧪 Sandbox	🚀 Production
API base	`https://sandbox-api.opencard.io`	`https://api.opencard.io`
Application API	`.../api/v1/application`	`.../api/v1/application`
OAuth token	`.../oauth/token`	`.../oauth/token`
Register	sandbox-api.opencard.io/register	api.opencard.io/register
Signing pages	`sandbox-api.opencard.io/accounts/.../sign/...`	`api.opencard.io/accounts/.../sign/...`

Everything is isolated — credentials, data, webhook secrets, signed documents. Separate universes.