Stax
Subscription-priced embedded payments for ISVs, offering interchange-at-cost processing through Stax Connect.
Overview
Stax (formerly Fattmerchant) offers a unique subscription-based payment model where merchants pay a flat monthly fee and process at interchange cost. Stax Connect is their ISV-focused embedded payments platform with white-label capabilities and API-first design.
For the latest on Stax's ISV capabilities, documentation, and partner programs, visit staxpayments.com.
Pricing
Subscription (interchange-plus + flat monthly)
Subscription model: merchants pay $99-$199/month flat fee and process at interchange cost (0% markup). ISV partners earn revenue share on subscriptions and transactions.
Full pricing breakdown →Pros
- ✓ Stax Connect — embedded payments platform built for ISVs
- ✓ Subscription pricing model (interchange-plus with flat monthly fee)
- ✓ API-first with white-label capabilities
- ✓ Strong mid-market ISV focus
Cons
- ✗ Subscription pricing model may not suit low-volume merchants
- ✗ Less international coverage than Stripe or Adyen
- ✗ Smaller developer ecosystem
- ✗ Brand recognition lower than major platforms
ISV Fit
Best for ISVs whose merchants process high volumes where interchange-at-cost plus subscription provides savings over percentage-based pricing. The model is less attractive for low-volume merchants.
Stax Review: An ISV’s Perspective
This review evaluates Stax specifically from the ISV and SaaS platform perspective. While many reviews focus on small business or e-commerce use cases, ISVs have fundamentally different requirements: embedded payment facilitation, sub-merchant onboarding, revenue sharing, and white-label capabilities.
What ISVs Should Know About Stax
Stax scores 3.9/5 in our ISV-focused evaluation. The rating reflects the platform’s capabilities for embedded payments, not general payment processing. A provider can be excellent for direct merchants but mediocre for ISV integration — and vice versa.
For ISVs, the key evaluation criteria are:
- Merchant onboarding speed: How quickly can your software’s users start accepting payments? Minutes vs. days matters for activation rates.
- Revenue sharing model: What percentage of each transaction does your ISV earn? This directly impacts your payment revenue line.
- White-label capabilities: Does the payment experience carry your brand or the processor’s? This affects merchant perception and switching costs.
- API quality and documentation: ISV developers need clean APIs, comprehensive docs, and responsive sandbox environments.
- Compliance burden: How much of the PCI, KYC/KYB, and regulatory compliance does the platform handle vs. leaving to the ISV?
Who Should Consider Stax
Stax fits certain ISV profiles better than others. The platform’s strengths align with specific vertical markets, transaction volumes, and integration depth requirements. ISVs should evaluate Stax alongside 2-3 alternatives using a structured scorecard that weights ISV-specific capabilities higher than general payment features.
The Bottom Line
No payment platform is perfect for every ISV. Stax has clear strengths and weaknesses that make it ideal for some integration patterns and less suitable for others. The right choice depends on your specific vertical, merchant profile, transaction volumes, and how much control you want over the payment experience.