It is currently not possible to redirect from one Zendesk Help Center article to another Zendesk Help Center article or an external URL.
This is ideally done using a DNS 30x redirect, which isn't currently supported by Zendesk.
This solution uses hashmapping, so it ideally will not have large performance implications.
How to Use :
1) Copy and paste the code and put it into your document_head.hbs file. It needs to be in <script> tags.
2) Make sure to replace the couple sections of code that are called out!
3) Add redirects! The format is ['old article id'] = new article id; The article id is the number found in the knowledgebase URL: helpcenter.com/hc/en-us/articles/360000857366
If redirecting outside of the Help Center, use the format ['old article id'] = "new url".
4) Archive any articles that are being redirected from. This ensures that users get to the new page, and not to a Zendesk authentication page.
I made a video! This will hopefully clarify any weird issues that people encounter.