monaco-editor-auto-typings is a plugin for Microsoft's Monaco Editor, which automatically loads type declarations when you enter import-calls in the code editor.
Try it out in the demo on the left! Add some imports to some libraries available on npm, such as import express from 'express';, and see that any imported variables are automatically strictly typed.
monaco-editor-auto-typings comes with lots of customization options, but is still a one-liner to add to your project. It works by loading declarations from UnPkg. They can then be optionally cached in localStorage or elsewhere.