Based on our record, Phabricator should be more popular than Code Collaborator. It has been mentiond 3 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
Collaborator by SmartBear is a peer code and document review tool for development teams. In addition to source code review, Collaborator enables teams to review design documents too. A 5-user license pack is priced at $535 a year. A free trial is available depending on your business requirements. - Source: dev.to / over 2 years ago
My company has used Phabricator, which is an alternative to Azure Devops, for about 5 years. A few days ago they announced that the project won't be maintained anymore, so we are looking into alternatives. We have around 50 devs+product folks that use Phabricator at the moment. Source: almost 4 years ago
You also mention Gitlab is close to what you would like - maybe Phabricator is even closer: https://phacility.com/phabricator/. Source: about 4 years ago
Https://phacility.com/phabricator/ I think checks most of those boxes, maybe all. Source: about 4 years ago
Atlassian Crucible - Collaborative peer code review tool.
GitLab - Create, review and deploy code together with GitLab open source git repo management software | GitLab
Review Board - Stress-free code review for teams of all sizes
GitHub - Originally founded as a project to simplify sharing code, GitHub has grown into an application used by over a million people to store over two million code repositories, making GitHub the largest code host in the world.
Upsource - Upsource provides unified access to all your projects stored in Git, Perforce, Mercurial or Subversion.
BitBucket - Bitbucket is a free code hosting site for Mercurial and Git. Manage your development with a hosted wiki, issue tracker and source code.