This open source repository contains the standard QL libraries and queries that power LGTM, and the other products that Semmle makes available to its customers worldwide.
LGTM has extensive documentation on getting started with writing QL. You can use the interactive query console or the QL for Eclipse plugin to try out your queries on any open-source project that's currently being analysed.
We welcome contributions to our standard library and standard checks, got an idea for a new check, or how to improve an existing query? Then please go ahead an open a Pull Request! Before you do though, please take the time to read our contributing guidelines.
The lgtm queries are licensed under Apache License 2.0 by Semmle.