Mark Nelissen

I use Slack because it offers the best experience, even on the free tier (which we're still using). As a comparison, I have had in depth experience with HipChat, Stride, Skype, Google Chat (the new service), Google Hangouts (the old service). For self hosted, Mattermost is open source and claims to support most Slack integrations, but I have not extensively investigated this claim.

I use npm because I also mainly use React and TypeScript. Since several typings (from DefinitelyTyped) depend on the React typings, Yarn tends to mess up which leads to duplicate libraries present (different versions of the same type definition), which hinders the Typescript compiler. Npm always resolves to a single version per transitive dependency. At least that's my experience with both.