HubSpot has several options for integrating with CRMs. HubSpot offers a native integration with Salesforce and Zapier, a third-party service that offers simple API integrations with over 250 services, including many CRMs. Check out the directory of HubSpot-supported and third-party integrations. Please note that all third-party integrations are supported by their developer; contact information can be found on the integration listing page.
If you're a developer looking to learn more about building a custom integration with HubSpot, check out the CRM integration guide. HubSpot also has many partners that can work with you to create a custom CRM integration that fits your needs. Check out the agency directory.