10. Google Maps

Google Maps
Avery Hartmans/Business Insider

Google's mapping app is perpetually among the top 10 apps in the App Store. In the first three months of the year, Google Maps was downloaded an estimated 22.4 million times on iPhones worldwide. 

10. iQiyi

iQiyi app

Founded by Chinese internet giant Baidu, iQiyi is a YouTube-style video streaming app. The company claims there are 481 million iQiyi users and that people are spending 5.6 billion hours on the app every month, according to TechCrunch

During the first quarter, iQiyi had an estimated 22.6 million downloads. 

9. QQ

QQ app

QQ is an app created by Chinese tech conglomerate Tencent. The app offers Facebook Messenger-style instant messaging, along with online games, music, shopping, and more. 

QQ was downloaded an estimated 22.6 million times in the first quarter of 2018. 

7. WeChat

A WeChat Pay system is demonstrated at a canteen  in Guangzhou, China May 9, 2017. Picture taken May 9, 2017.     REUTERS/Bobby Yip
Thomson Reuters

Tencent's WeChat app was also among the most downloaded apps last quarter with an estimated 28.9 million downloads worldwide. 

WeChat is capable of messaging, social media, and mobile payments. As of March 2018, WeChat had more than 1 billion monthly active users

6. Facebook

Facebook app on iPhone

Despite its tumultuous 2018 thus far, Facebook remains one of the top iPhone apps in the world. The app is perennially a top-10 app in the App Store, and was downloaded an estimated 29.4 million times during the first quarter.

5. Instagram

Jirapong Manustrong / Shutterstock.com

Instagram is the most popular app in Facebook's lineup. The app is the second-most popular free app in the App Store and was downloaded an estimated 31 million times in the first three months of the year. 

4. Messenger

Facebook Messenger on iPhone

Facebook's Messenger app is the third-most popular free app in the App Store and had an estimated 31.3 million downloads in the first quarter of 2018. 

3. WhatsApp

WhatsApp for iPhone

WhatsApp, the encrypted messaging service that Facebook bought in 2014, has 1.5 billion monthly users. Last quarter, the app was downloaded an estimated 33.8 million times. 

2. YouTube

YouTube app for iPhone

Google-owned video platform YouTube is consistently the top free iPhone app in the App Store. In the first quarter of the year, YouTube had an estimated 35.3 million downloads. 

1. Tik Tok

Tik tok app

Known as Douyin in China, Tik Tok is a music video and social media app. The app lets you shoot and edit short clips, then add music and special effects to them. Tik Tok is owned by the same parent company that bought social video app Musical.ly for $1 billion last year. 

According to Sensor Tower, Tik Tok has become a "total phenomenon" in China in recent months. In the first quarter of 2018, the app was downloaded an estimated 45.8 million times.