diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 2c8206cf..ee30fb33 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -18,6 +18,7 @@ We're trying to keep it simple and promote the best tools, not all of them.
 - Cross-platform / Accessible.
 - Privacy respecting.
 - Open Source / free software is preferred but not required.
+- Must list source code in [source_code.md](https://github.com/privacytoolsIO/privacytools.io/blob/master/source_code.md) (if applicable)
 - Prioritize Products without Vendor Lock-in (decentralized/self-hostable) or data interoperability.
 
 There can be exceptions if no software is available that meet the criteria.