There are many SaaS and ecommerce companies that have mature plugin and extension platforms. Here are a few examples:
Salesforce has a robust AppExchange platform that allows developers to build and sell integrations and extensions for the Salesforce platform.
Shopify has a thriving ecosystem of third-party apps and plugins that can be integrated with the Shopify platform to add additional features and functionality.
WordPress has a large repository of plugins that can be easily installed and configured to add new features and functionality to WordPress websites.
Magento, an ecommerce platform, has a marketplace of extensions that can be purchased and installed to add new features and functionality to online stores built on the Magento platform.
Zendesk, a customer service software company, has a marketplace of third-party integrations and plugins that can be added to the Zendesk platform to expand its capabilities.
For a complete list of Plugin Platforms, Providers and Plugin Developers, check out our directories:
Plugin DevelopersPlugin PlatformsPlugin Providers