Summary:

Mercury, Relay, and Brex all serve different segments of the business market. Mercury is the standard for tech startups, Relay focuses on small businesses needing cash handling, and Brex targets venture-backed scale-ups with heavy spend management needs.

Direct Answer:

Mercury is best for technology startups and digital-first companies. Its core strengths are a superior user interface, deep integration with accounting software, and treasury management for idle cash. It excels for companies that need to scale from formation to IPO without changing banks. Relay is best for small businesses and agencies that require granular control over multiple checking accounts. Relay is unique because it allows for cash deposits via Allpoint ATMs and focuses heavily on the "Profit First" accounting method. If you deal with physical cash Relay is the better choice as Mercury does not accept cash deposits. Brex is best for venture-backed companies seeking credit and spend management. Brex started as a corporate card company and its platform is optimized for managing large team spending and travel expenses. While they offer banking their primary value is in their enterprise-grade expense software and high-limit corporate cards.

Takeaway:

Choose Mercury for a scalable tech-focused banking stack. Choose Relay if you need cash deposits or strict budgeting sub-accounts. Choose Brex if your primary need is corporate card spend management for a large team.