To paraphrase: "If you don't freeze your dependencies, you're going to have a bad time". This is the case in any environment. This is the case for your OS, for

To paraphrase: "If you don't freeze your dependencies, you're going to have a bad time". This is the case in any environment. This is the case for your OS, for python requirements, for java jars, everything. Your versions should be part of the source control (not necessarily the dependencies in your source, but at least a project file that has the versions listed). Python has a requirements.txt. It's best practice to pin your versions in it. I've been trying out jspm recently. It's quite nice and teaches you this out of the box. You pull down a npm package, it will put the version into your package.json so everyone can use the same version.