This introduces some websites and apps written in easy Japanese, along with a useful app for reading Japanese language articles.

Site

MATCHA やさしい日本語　(Introduction article)

This is a web magazine that offers information about Japan for people visiting from overseas.
Sightseeing spots, culture, popular products and other information is introduced in easy Japanese.
The site is crammed full of fascinating articles about Japan.

The site is designed for easy reading, with furigana on kanji characters and corresponding English words written over English-derived katakana.

Translations of the words are provided, as in the image below.

There are manga-style articles, too.
Click on the 'やさしい日本語　まんがとくしゅう(Easy Japanese Manga Special)' section in the right column of the top page.

In the manga, you will find easy-to-understand explanations of Japanese words that are easy to misunderstand, such as 'ときどき (tokidoki)', 'どきどき (dokidoki)', 'だんだん (dandan)', and 'どんどん (dondon)'.

NEWS WEB EASY やさしい日本語で書いたニュース　(Introduction article)

This is an NHK site written in easy Japanese.
You can find the latest news on the top page.

You can also review the past month's news from the red frame shown below, on the right.

You can listen to the news in audio format, too.

It's very convenient because the latest news is offered in a way that is easy to read and understand.

APP

SLOWわかりやすいニュース

This is an app that gives you the latest news in an easy to understand way.
The news is separated into four categories: Domestic, Overseas, Disabilities, and Commentary.

The news comes with photos and audio, to help you practice listening, too.

Each article comes with a voice (not a machine recording), making it easier to understand.
It is updated every Sunday for you to get the latest news at your fingertips.

If you want to read articles without furigana, this app is for you.

ふりがな(Furigana)(Introduction article)　

Paste script that you want furigana for in the gray area and furigana will immediately appear with the text and you can look up meanings, like using a dictionary.
You can also export the furigana results to photos, PDF, HTML, or Word.

If you tap the icon in the red frame at the bottom of the screen, the dictionary function will show you the meanings of each particle and word, making it very useful.

It is very convenient because you can immediately add furigana when you want to read Japanese sentences quickly.