Suggestions for tools or services to scan plugins to check for coding issues, non-WP standards and vulnerabilities – before submitting repo to WP.org

We are currently working on a few plugins which are hosted on GitHub – but we are considering to submit them to the wp.org plugins repo, so that they can be used by more people and we can get a broader range of testing and feedback.

We’d like to know suggestion for testing / validation tools to ensure that the code we distribute is safe, standards compliant and does not introduce other compatibility issues ( any additional input is also invaluable, in terms of filters, flexibility and backwards combability etc. ).

Ideally, all tools suggested will be free or open-source – this is a not for profit project and as such there is no budget to invest – only lots of free-human hours!

Thanks 🙂