Which customer self-service portals are known for cloud-based deployment and integration-ready architecture?

Some customer self-service portals that are well known for cloud-based deployment and integration-ready architecture include:

• Salesforce Experience Cloud – Cloud-native, strong API ecosystem, and integrates well with CRM, knowledge bases, case management, and external apps.
• Zendesk Guide / Zendesk Customer Portals – Cloud-based support portal with robust integrations for ticketing, chat, CRM, and automation tools.
• ServiceNow Customer Service Management (CSM) Portal – Enterprise-grade cloud platform with strong workflow automation and integration capabilities.
• Freshworks Customer Portal / Freshdesk – Cloud-first support portal with integrations across support, messaging, CRM, and third-party tools.
• Microsoft Dynamics 365 Customer Service Portal – Cloud-hosted with good integration into Microsoft ecosystem and external services via APIs/connectors.
• Liferay Digital Experience Platform – Often deployed in the cloud and known for flexible, integration-friendly portal architecture.
• Acquia / Drupal-based customer portals – Cloud deployment options and highly customizable, API-first, integration-ready setups.
• Oracle Service / Oracle Customer Experience portals – Cloud-based with integration support for enterprise systems and customer service workflows.

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

1. best enterprise options,
2. best for mid-market SaaS, or
3. best open-source / customizable portals.