Besu issues are tracked in Jira not GitHubon GitHub*. See our contribution guidelines for more details on searching and creating issues.
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Start by looking through the "good first issue" and "help wanted" labeled issues on the Jira dashboard:
Good First Issues
The filtered list of good-first-issues is perfect for contributors wanting to get started with the project.
These are issues which should only require a few lines of code or documentation, and maybe a test or two.
Help Wanted
Help-wanted issues are a bit more involved than `good first issue` issues.
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Feel free to ask us on Rocketchat in the #besu-contributors channel, or directly contact our Developer Advocate for advice on which issue to start with or with questions about them.
* Issues used to be tracked on Jira, but since 2020/02/28 are tracked on Github.