Do you put Babel and Webpack in devDependencies or Dependencies?

I'm new to npm and don't really understand what should go into dependencies vs. devDependencies. I know that for testing libraries they should go into dev, but how about for things like babel and webpack? Should they be in dev too, because they're only used to transcompile es6 and JSX into vanilla JS? My understanding is that when you deploy to heroku, it do the transcompiliation with the necessary libraries already, so there's no need to host them on production?

  "dependencies": {
    "babel-core": "^6.7.7",
    "babel-eslint": "^6.0.4",
    "babel-loader": "^6.2.4",
    "babel-plugin-react-transform": "^2.0.2",
    "babel-plugin-transform-object-rest-spread": "^6.6.5",
    "babel-plugin-transform-react-display-name": "^6.5.0",
    "babel-polyfill": "^6.7.4",
    "babel-preset-es2015": "^6.6.0",
    "babel-preset-react": "^6.5.0",
    "bootstrap": "^3.3.7",
    "css-loader": "^0.23.1",
    "es6-promise": "^3.2.1",
    "eslint": "^2.9.0",
    "eslint-plugin-babel": "^3.2.0",
    "eslint-plugin-react": "^5.0.1",
    "express": "^4.13.4",
    "extract-text-webpack-plugin": "^1.0.1",
    "file-loader": "^0.9.0",
    "lodash": "^4.15.0",
    "react": "^15.0.2",
    "react-addons-css-transition-group": "^15.0.2",
    "react-dom": "^15.0.2",
    "react-redux": "^4.4.5",
    "react-transform-catch-errors": "^1.0.2",
    "react-transform-hmr": "^1.0.4",
    "redbox-react": "^1.2.3",
    "redux": "^3.5.2",
    "redux-form": "^6.1.0",
    "rimraf": "^2.5.2",
    "style-loader": "^0.13.1",
    "webpack-dev-middleware": "^1.6.1",
    "webpack-hot-middleware": "^2.10.0"
  },
  "devDependencies": {
    "babel-register": "^6.9.0",
    "chai": "^3.5.0",
    "mocha": "^2.5.3",
    "sinon": "^1.17.4",
    "webpack": "^1.13.2"
  }

The babel and webpack packages will go into the devDependencies section because these packages are used in when transpiling and bundle-ing your code into vanilla javascript in the bundle.js & etc file(s).

In production you will run your code off the bundle.js build/generated code will not require these dependencies anymore.

Despite what basically everyone says, I'm going to offer a piece of sanity... it's really quite simple:

Is your project going to be npm installed by another project? a.k.a are you authoring a npm module? will it end up in another projects package.json?

No?

Then put everything in dependencies.

Yes?

• dependencies: Things you want downstream consumers and project developers of your project to have installed:
• peerDependencies: Things your downstream users need to make sure they have installed
• bundleDependencies: Things your downstream users will need, and won't need to install separately because when you npm publish, these will be "bundled" with your package.
• optionalDependencies: Things that are nice to have but the absence of will not cause fatal error
• devDependencies: things only used while working on your project.

The short of it is this: modules do not magically get installed differently. They either get installed or they do not.

Dev dependency is which only use for the development server, these are devDepedency: All the packages which are not using in source code or imported are devDependencies

"babel-cli": "^6.26.0",
"babel-core": "^6.26.0",
"babel-loader": "^7.1.4",
"babel-preset-env": "^1.6.1",
"babel-preset-react": "^6.24.1",
"clean-webpack-plugin": "^0.1.19",
"copy-webpack-plugin": "^4.5.1",
"css-loader": "^0.28.11",
"file-loader": "^1.1.11",
"html-webpack-plugin": "^3.2.0",
"mini-css-extract-plugin": "^0.4.0",
"node-sass": "^4.8.3",
"optimize-css-assets-webpack-plugin": "^4.0.0",
"prop-types": "^15.6.1",
"sass-loader": "^7.0.1",
"style-loader": "^0.21.0",
"uglifyjs-webpack-plugin": "^1.2.5",
"webpack": "^4.6.0",
"webpack-cli": "^3.1.1",
"webpack-dev-server": "^3.1.9"