Thanks, operator. Good morning and evening to everyone on the call, and welcome to Aurora Mobile's Q1 2019 Earnings Call. Today, I am very pleased to share with you our first quarter results in the 2019.
To kick off this call, I would like to take a few minutes on various key operating data that we have achieved in this quarter. Firstly, the number of mobile apps utilizing at least one of our developer services, or the cumulative app installations, averaged 1.165 million as of March 31, 2019 from approximately 785,000 year-over-year. For quarter-on-quarter basis, we continue to see a steady stream of new apps, approximately 30,000 new apps a month using our developer services SDK. The notable customer win in this quarter included [indiscernible], [ Kanji ], Clean Master, QQ Reader.
For our new product JVerification, since launching end of Q4 last year, we have gained strong interest from the developer community. A few thousands of customers are currently in testing period, including QQ Reader, [indiscernible], [indiscernible] and [ Kuwo ].
Secondly, the cumulative SDK installations have increased to 22.7 billion as of March 2019 from 13.1 billion year-over-year. Today, the number of monthly active unique mobile devices we cover has continued to increase to 1.07 billion in March 2019 from 925 million in March 2018.
Lastly, in the first quarter of 2019, we have seen the number of paying customer increased to 1,951 from 1,348 a year ago. With the healthy and steady growth of this operating data, the total revenues from Q1 2019 were CNY 230.5 million, which represents an increase of 82% year-over-year.
Now let me further break down each of our business lines. Firstly, developer services. Within the 3 months ended March 31, 2018 and the 3 months ended March 31, 2019, our revenues from developer services increased by 47% from CNY 12.5 million to CNY 18.3 million, which was mainly due to the growth in the number of customers from 894 to 1,275 year-over-year, while apps remain stable.
Second, on our data solution business lines, during the same period, our revenue from data solutions increased by 86% from CNY 114 million to CNY 212 million. The 86% growth was primarily due to the increase in both the number of paying customers and the increase in average spending per customer.
For targeted marketing business, the revenue has grown 90% year-over-year. This increase was mainly due to both the increase of number of paying customer and ARPU.
Our targeted marketing business, which is purely performance based continued to expand its customer base as well as increase customers' wallet share, which has generated sequential growth in 9 consecutive quarters since we launched this business more than 2 years ago. We continue to gain more advertising dollars from customers through the delivery of higher ROI. Year-over-year, the ARPU has increased about 28% for targeted marketing, a strong evidence of customers shifting more advertising budget to us.
During the first quarter, which is traditionally a slow and challenging quarter for the entire advertising market in China due to Chinese New Year, we managed to record healthy revenue growth. Our strategy to broaden our advertising customer verticals continue to execute well, and we have seen solid results.
The highlight for this quarter is revenue mix is more balanced, with financial accounting for less than 40% of total ad revenue, down from 50% last quarter. And mobile gaming continued to gain momentum. It now accounts for 16% of total revenue, up from 10% in fourth quarter.
Media and entertainment vertical continued to grow nicely quarter-on-quarter with about 30% ad revenue contribution. The others mainly include education, e-commerce, auto, and this segment accounts for more than 15% total ad revenue.
Customer retention in the quarter remains very high. For the top 20 paying advertising customer in fourth quarter, we had 0 customer attrition during this quarter.
On our media source. For the first quarter of 2019, self-owned SSP contributed approximately 15% of ad inventory. And in this quarter, Tencent GDT accounted for about 30% of total advertising inventory on dollar term, similar to that in the first quarter 2019.
Now I'll turn the call to Fei, who will share with you on the Q1 performance of our other 3 business lines within the data solutions.