Reko API is an Open Web API to match similar MyAnimeList users and get anime recommendations from their lists.
You can check out its source code on GitHub.
If you are willing to implement Reko API on your website or app, please read the API Documentation.
Added GET Random Recommendations
Recommendations ordering tweaks
New recommendations ordering
Already watched recommendations bug fixed
Empty responses no longer throw errors
Added GET Specific User Recommendations
Added similar users pagination (batch) in GET User Recommendations
Introduced hash based algorithm
API simplified overall
Added GET Compare Users