Aurora Mobile. Welcome to Aurora Mobile's second quarter earnings release presentation. Our Q2 earnings release was published on August 28. For today, I would like to take this opportunity to share with you the great numbers that we have recorded for the quarter ended June 30, 2025. We are very pleased with the results, and I trust that you will share my sentiment, too, by the end of this call. Next, I'll go into the significant milestones achieved by the company in the second quarter of 2025. Later, I'll provide a detailed analysis of our recent operational results, a breakdown of the financial data reflecting our business momentum, and share the strategic roadmap guiding our growth this quarter. This is a moment that we have been eagerly anticipating, as we are excited to share our progress and the stories behind our performance with our valued investors, partners, and stakeholders.
Next, in part one, I'll walk through Aurora Mobile's key business development during the second quarter of 2025. From our global flagship product, EngageLab, to our AI agent platform, GPT-Bots, let's take a closer look now at the milestones that are shaping our long-term trajectory. Our EngageLab continues its strong growth momentum in Q2 2025. The number of customers increased by 171% year-over-year, and the cumulative contract value increased by 265% year-over-year. Q2 revenue grew by 67% year-over-year and 24% quarter-over-quarter, demonstrating the robustness of our full-cycle operations. Notably, EngageLab's global expansion has become increasingly effective. It has not only emerged as the company's second growth driver, but also continuously injects new momentum into the overall business ecosystem, becoming a vital pillar supporting the group's long-term development. In Q2, we have partnered with China Unicom to launch a smart integrated verification international addition to our EngageLab platform.
In this collaboration, EngageLab fully leverages its strengths and utilizes China Unicom's extensive network to provide international clients with a one-click mobile phone verification service. This fully confirms EngageLab's leading technological strengths and the service capability in the global user identity verification field, clearly highlighting the core position and widespread influence within the industry. In the future, we will continue to strive to create more valuable collaboration. Our AI agent platform, GPT-Bots, has successfully integrated the majority of the mainstream large language model and plans to complete the integration of more in the future. We firmly believe that this initiative will further optimize the quality of our service for our customers, enhancing user satisfaction and experience through more precise support and more efficient responses. As a benchmark leader in the enterprise-level AI agent sector, GPT-Bots remains focused on core customer needs.
To establish a more reliable service assurance, the platform has successfully obtained multiple industry-recognized certifications. We actively participate in various global exhibitions, proactively showcasing our core product and services' advantages to customers worldwide. Our high-quality solutions have garnered widespread praise and recognition. In Q2 of 2025, our board of directors has approved a strategic initiative to invest up to 20% of our cash and cash equivalents in cryptocurrency and digital assets as part of our treasury management plan. This initiative is designed to modernize our treasury practices while maintaining sufficient liquidity for operational needs. As I shared earlier, EngageLab has demonstrated robust growth vitality, with various business metrics continuing to rise, showcasing impressive development momentum. The developer subscription business in Q2 2025 revenue was at RMB 53.7 million, marking four consecutive quarters of revenue above the RMB 50 million mark. Our all-business line recorded double-digit year-over-year revenue growth.
Our net dollar retention for developer subscription service at 99%. We achieved our very first profitable quarter in the history. Gross profit increased by 13% year-over-year and 1% quarter-over-quarter. Gross margin consistently at a high level at 66.4%. OpEx is kept at optimal levels to support revenue growth acceleration. Equally important, operating cash recorded a net inflow of RMB 7.9 million. We successfully reached our very first GAAP profitability milestone in history in this quarter. Behind this impressive performance lies the unwavering dedication and teamwork of all our employees. We have made significant breakthroughs and solid progress in both business expansion and financial performance. Looking ahead, we are confident in the group's continued profitability and deliver high-quality earnings reports with steady growth, fulfilling the trust and expectations of our investors. Next, our total revenue grew 13% year-over-year to RMB 89.9 million.
Developer service revenue grew by 14% year-over-year and 3% quarter-over-quarter. Boutique applications grew by 10% year-over-year and decreased by 4% quarter-over-quarter. Subscription revenue rose 12% year-over-year, driven by growth in customer numbers and increase in OPW. Value-added services revenue surged 30% year-over-year and 21% quarter-over-quarter due to the Q2 online shopping festival and increased ad spending allocation to us. Boutique application revenue rose 10% year-over-year and decreased 4% quarter-over-quarter. Financial risk management revenue grew 27% year-over-year due to the acquisition of new customers. Gross profit rose 13% year-over-year to RMB 59.6 million, reaching the highest level in the past 10 quarters, and the margin maintained at a high level. The improvement is due to a higher contribution from scalable high-margin service line. The total operating expenses remain stable at RMB 60.8 million. R&D, sales and marketing, and G&A expenses were kept at a reasonable range, and spending is well controlled.
Deferred revenue remains at a high level, reaching RMB 156.1 million. As a key indicator of our ability to receive money in advance and market trust, this figure not only provides a clear testament of our strength and stability of the group's cash flow, offering solid funding for daily operations and strategic investment, but also underscores the health of the foundation of our business model. It reflects the customers' long-term recognition of our service and their willingness to prepay, injecting predictable momentum into the continued growth of our business. Next, cash and cash equivalents and restricted cash reached RMB 119.8 million. Our deferred revenue continues its 21 quarters straight above RMB 100 million. AR turnover days reduced to 54 days, showing strong assurance to revenue growth. NDR for developer service held strong at 99%. This metric shows that we are operationally efficient and financially prepared for future growth.
These are pretty much the good numbers that I have to share with you all. An investor can stay updated on Aurora Mobile's latest development through the following platforms. You can follow us at X, Facebook, LinkedIn, StockTrade, and Weibo. Thank you once again for your attention during this meeting. Overall, I believe you all would agree with me that it was a great Q2 numbers that we have delivered. Your engagement is vital to driving force for our progress. Looking ahead, we kindly ask everyone to continue focusing on our development dynamics. We are confident that our solid business foundation has sustained growth momentum, and the company will continue to deliver outstanding performance. Thank you.