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--- a/README.md
+++ b/README.md
@@ -11,6 +11,11 @@ exposing both the APIs of PAM and NSS. It can be used:
  * in `/lib/libnss_webapi.so` as NSS database module
  * in `/sbin/nss_pam_webapi_cached` as caching daemon to speed up requests
 
+The server-side de facto reference implementation is
+[AlekSIS-App-NIS](https://edugit.org/lanki.cloud/glue/AlekSIS-App-NIS),
+which adds system account functionality to the [AlekSIS](https://aleksis.org)
+school information system.
+
 ## System authentication (PAM module)
 
 The following OAuth flows are implemented for system authentication: