LGTM vs SourceTree: What are the differences?
Developers describe LGTM as "A simple pull request approval system for GitHub". LGTM is a simple pull request approval system using GitHub protected branches and maintainers files. Pull requests are locked and cannot be merged until the minimum number of approvals are received. Project maintainers can indicate their approval by commenting on the pull request and including LGTM (looks good to me) in their approval text. On the other hand, SourceTree is detailed as "A free Git GUI client for Windows and macOS". Use the full capability of Git and Mercurial in the SourceTree desktop app. Manage all your repositories, hosted or local, through SourceTree's simple interface.
LGTM belongs to "Tools for GitHub" category of the tech stack, while SourceTree can be primarily classified under "Source Code Management Desktop Apps".
LGTM is an open source tool with 936 GitHub stars and 92 GitHub forks. Here's a link to LGTM's open source repository on GitHub.