GitLab offers Free Trial, but Phase does not.
GitLab is designed for Large Enterprises, Medium Business and Small Business.
Phase is designed for and undefined.
Pricing for GitLab Starts at $19/User/Month whereas for Phase Starts at $12.00per user / month when Billed Yearly.
Some top alternatives to GitLab includes Codeship, Semaphore, CircleCI, Bamboo, AutoRABIT CI, Buildkite, CloudBees Core, Travis CI and Bitbucket.
Some top alternatives to Phase includes and undefined.