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List of some popular CI servers

• Bamboo
• Hudson
• Jenkins
• TeamCity

Cloud-based CI

• Amazon DevOps
• TrevisCIAzure DevOps (previously Team Foundation Server (TFS))
• CircleCI,
• Travis CI, 
• drone.io
• Codeship
• Wercker

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Personal Experience

Having used TeamCity and Jenkins as enterprise build servers, I have seen a preference towards Jenkins.

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