22 Useful Website for Frontend Engineers (Always updated)

TS/JS

Bit.dev

Bit is a scalable and collaborative way to build and reuse components. It's everything you need from local development to cross-project integrations.
https://bit.dev/

Create App

config.js generator for webpack, Parcel, and Snowpack
Create App supports react, svelte and vue.
https://createapp.dev/

TypeScript Playground

TypeScript Playground is useful to check the latest version's typescript's features.
https://www.typescriptlang.org/play

JavaScript Minifier

Actually, there are some CLI tools and functionalities to minify js, but this can be useful when you don't use any module bundlers and task runners. It's easy to use since we just need to copy and paste js code.
https://javascript-minifier.com/

unminify (js/css/html/xml/json)

This can be useful when you work on xxx.min.js and need to check the code for debugging.
https://unminify.com/

openbase

openbase is a very useful website when you are looking for npm packages for your project since we can see other developers' reviews about the packages.
https://openbase.io

@types search

Search engine for @types files
https://www.typescriptlang.org/dt/search?search=

Prettier Playground

https://prettier.io/playground/

JSLint

Probably most of you use eslint, but when you don't want to use any packages for lint, this might be good.
https://jslint.com/

JWT.IO

JSON Web Tokens are an open, industry standard RFC 7519 method for representing claims securely between two parties.
JWT.IO allows you to decode, verify and generate JWT.
https://jwt.io/

CSS

CSS Gradient

CSS Gradient is a happy little website and free tool that lets you create a gradient background for websites.
https://cssgradient.io/

CSS clip-path maker

The clip-path property allows you to make complex shapes in CSS by clipping an element to a basic shape (circle, ellipse, polygon, or inset), or to an SVG source.
https://bennettfeely.com/clippy/

Layoutit!

Layoutit generates css for grids design.
https://grid.layoutit.com/

HTML

Placeholder.com

Placeholder.com is a free image placeholder service for web designers, serving billions and billions of images each year.
https://placeholder.com/

other

CanIUse

https://caniuse.com/

favicon.io

The only favicon generator you need for your next project. Quickly generate your favicon from text, image, or choose from hundreds of emojis.
https://favicon.io/

PATTERNIFY

http://www.patternify.com/

regular expressions 101

https://regex101.com/

tiny png

https://tinypng.com/

Google Fonts

https://fonts.google.com/

fontello

https://fontello.com/

Websu

Websu helps you optimize your web applications for speed by generating detailed reports.
https://websu.io/