The phrase "kind of things" is correct and usable in written English. You can use this phrase when you are trying to summarize a group of related items without being too specific. For example, you could say, "I'm interested in all kinds of things: art, music, reading, and outdoor activities.".
All kind of things".
"Unfortunately, these kind of things happen.
What kind of things is Evernote building?
"What kind of things?" Taussig asked.
TA: What kind of things?
Like what kind of things?
Those kind of things don't happen overnight.
I love the desktop app, it’s always running on my Mac. Ludwig is the best English buddy, it answers my 100 queries per day and stays cool.
Cristina Valenza
Retail Lead Linguist @ Apple Inc.