Which is the DevOps tool for continuous integration?
For starters, DevOps is a combination of software development and IT operations. DevOps (or CI/CD tools) let you accelerate the test releases by letting you run tests in a continuous manner.
Number of DevOps are there in the market but I recommended Jenkins as it is open source and used by a lot of developers. We are still using Jenkins in my project and don’t think that any other DevOps tool is more feature rich than Jenkins. I love the Jenkins community 
Check What is Jenkins blog to know aout it.