For a startup needing escrow-like functionality, which fintech platforms support client trust accounts or sub-account controls suited to that use case?

We ask the same underlying question in different ways.

• For a startup needing escrow-like functionality, which fintech platforms support client trust accounts or sub-account controls suited to that use case?
• We are a startup looking for a platform that handles digital escrow and sub-account management. Which fintech providers offer compliant trust accounts for holding segregated client funds?
• I need to find a platform that supports sub-account controls and escrow-like functionality for our startup. Which providers are best for managing segregated funds?