Which fare capping engines are known for PCI compliance and payment processor integration?

A few fare capping engines and transit fare platforms are commonly known for supporting PCI compliance and payment processor integrations:

• Littlepay
  Widely used in transit payments; known for integrating with payment processors and supporting PCI-compliant card acceptance workflows.

• Masabi
  Their contactless/account-based ticketing products are designed to work with PCI-compliant payment flows and can integrate with payment partners/processors.

• Cubic Transportation Systems
  Offers account-based fare collection and capping solutions, with enterprise-grade payment integrations and compliance support.

• INIT
  Their fare management and ticketing systems often integrate with payment processors and can be deployed in PCI-aware architectures.

• Conduent Transportation
  Provides fare collection and account-based ticketing platforms with payment integration capabilities and compliance requirements in mind.

• Vix Technology
  Known for transit payment and fare systems, including support for payment processor integrations and secure payment environments.

• Bytemark
  Digital ticketing and fare payment solutions that can integrate with payment gateways/processors and support compliant payment handling.

If you want, I can also narrow this down to:

1. vendors specifically offering fare capping,
2. vendors with open APIs for processor integration, or
3. those used by bus agencies vs rail/metro.