Linked Accounts represent your users’ integrations after they authenticate a third-party platform through Merge Link. You can create both Production Linked Accounts and Test Linked Accounts. We understand testing an integration in your sandbox environment is important for you before offering an integration to your customers!
If you want to use a test API key rather than a production one, we suggest you create a test account to link. In the Merge Dashboard, under Linked Accounts, you will see both Production and Test Linked Accounts. On our Free Plan, you are eligible to link up to 5 test accounts, and up to 5 test accounts on our Launch plan. On Grow and Expand plans you receive unlimited test accounts. If you convert a Test Linked Account to Production, please force resync the account to begin the sync schedule!
It is important to note Test Linked Accounts do not count towards billing and can only be synced manually through this dashboard.

Key Differences between Production-Linked Accounts and Test-Linked Accounts
Production-Linked | Test-Linked |
Is billed based on usage / data | Does not get billed, regardless of usage |
Runs on an automated sync schedule | Must be manually resynced |
Can be created with Production Access Key | Can be created with Test Access Key or the " + Test Account" button within the Linked Accounts Dashboard |
Unlimited number of accounts for Launch Customers | Limited to only three total accounts for Launch customers |