You can get started using the query console on LGTM. On LGTM.com, you can write QL code to query open source projects directly—without having to download snapshots and libraries. If your organization uses LGTM Enterprise, you can use this to query private projects too. The query console provides autocomplete suggestions, the option to "jump to definition", and many more writing aids. Alternatively, you can install a QL plugin to write and run queries locally. For more information, see QL plugins and extensions. Once you have installed a plugin and obtained a snapshot to run queries against, you can start writing QL in your IDE.
If you are new to QL, start with the following topics:
For more examples and information about writing queries to run as part of custom analysis for your project, see Writing QL queries.
The Semmle QL 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. Contributions and improvements are welcome—visit the repository to learn more.
For more comprehensive information about QL, see the following reference topics: