What is sinopia?

Sinopia is a private package server that sits between your computer and the official npm registry. It lets you install and publish code packages privately, just like you'd do with public open-source packages, but for code you want to keep internal to your company. Here's the everyday use case: imagine your team has built some useful utilities or tools that you want to reuse across projects, but you don't want to publish them publicly or pay for a hosted private registry. You install Sinopia on a server, point your npm client to it instead of the public registry, and now you can publish and install your private packages like you would any public one. The server also acts as a cache, so if someone downloads a public package from npm.org, Sinopia remembers it. Next time you or a teammate needs that same package, it serves it from the cache instead of hitting the internet again, which is faster and helps if npm.org goes down temporarily. The project works by using your computer's file system instead of a complicated database setup. When you ask for a package, Sinopia first checks if it has a local copy. If not, it fetches it from npmjs.org, caches it, and gives it to you. You can also override public packages, if you've fixed a bug in someone else's code and want to use your version instead, just publish it locally with a slightly higher version number, and npm will prefer yours. The main appeal is simplicity: it requires almost no setup and no complex infrastructure to get running. The tradeoff is that some advanced npm features like tagging and deprecation aren't supported yet. It's built in JavaScript and can run anywhere Node.js runs, including Docker, and the community has created deployment tools like Chef and Puppet modules to make it even easier to set up at scale.