Umm ... requirements.txt and pypi? Sbt/Maven/Gradle and maven/ivy repos? package.json?
Unless you setup a local caching, non-deleting, JFrog artifactory for all your dependencies (only jar files are covered in the free version BTW, and there aren't any tools that handle all those repo types in the OSS world), you are going to depend on external URLs.
Locally caching dependencies is not trivial.