Apps used by millions must withstand enormous loads — even the slightest malfunction can lead to significant financial losses. Denis Saripov specializes in frontend optimization at one of the world’s largest social video platforms. Tens of millions of people use the app daily across more than 100 regions.
Denis spoke about the unique challenges of working with large-scale platforms, the problems developers face when optimizing massive applications, and the frontend optimization trends that will shape the industry’s future.
Denis, you’ve worked with products of various scales — from startups to a global short-video service, where your solutions impact millions of users. Has this journey influenced your approach to frontend architecture?
Architecture in startups is usually quite simple, but as the user base grows, it inevitably becomes more complex. Optimization challenges start to appear — especially in mobile applications. My experience working in a large corporation taught me the importance of dividing functionalities into separate modules. This modular approach helps keep the application under control and allows us to fine-tune specific features for users without affecting other parts of the system.
Such architecture makes it easier to quickly optimize performance and maintain system stability, which in turn attracts more users. In startups, these factors often don’t matter much, but in large corporations, even a 10% improvement in performance can significantly boost profitability and user engagement.
Tell us more about your current projects.
I work on increasing the engagement of its live-streaming feature — specifically, improving the gifting experience. In order to interact with streamers users need to have coins — an internal currency that users can spend on donations, gifts for streamers, and stickers.
We support multiple purchase channels and website is one of them. It’s also more convenient for users, since only the website allows them to buy a custom amount of coins. So I developed a mechanism that simplifies the transition from the app to the browser.
I designed the frontend for this mechanism — building a page that redirected users to the website. Once redirected, the user would immediately land on the page where they could select the number of coins — no extra steps required. The logic worked seamlessly, and the same approach was later used in other projects.
I also participate in developing promotional campaigns aimed at increasing purchases through the website. For example, periodic, public‑facing promotions designed to encourage engagement. I had to develop a separate flow for users participating in such promos. This approach attracts more users, drives additional traffic, and consequently increases the company’s revenue.
How does your approach to interface optimization change when millions of users interact with the product simultaneously, rather than just thousands?
Large companies operate across multiple regions, each with its own technical and legislative conditions. For example, to ensure faster load speeds in a specific region, you need to use servers located nearby. This means carefully planning where to rent server capacity and how to distribute it based on the number of users in each area. Smaller companies usually don’t face this issue, since their users are more far less dispersed around the globe.
The more users an app has, the greater the load — and as a result, interfaces can take longer to load when switching pages. If you can’t reduce loading time, you need to determine which information should appear first. For instance, this could be a promotional banner or a user’s activity history. If users immediately see key content, they’ll be more tolerant of incremental loading. Startups rarely deal with this kind of optimization since their traffic levels are typically not high enough to expose such issues.
Given that even minor delays in payment flows are critical, how do you ensure high responsiveness and reliability in interfaces?
The key is to visualize all user flows comprehensively and predict where bottlenecks might occur. It’s also important to consider corner cases — scenarios where several unusual factors overlap — and edge cases — situations at the limits of the system’s capacity. These can easily “break” an application, so it’s essential to handle them in code from the very beginning.
The problem is that such cases aren’t always obvious — everything may appear fine until certain users encounter errors. If this happens on a large scale, business metrics suffer: some users won’t wait for results and will simply leave.
To manage this, we collect anonymous statistics about failures, long load times, and timeouts. Then we configure alerts that notify us of spikes in such incidents. This allows us to respond promptly, analyze user behavior, and understand what caused the error. From there, we can identify the root cause and adjust the logic on either the frontend or backend.
Can you describe the direct impact frontend optimization has on business metrics — such as purchase frequency, site conversions, or user retention within flows?
The most effective way to influence business metrics through frontend work is to speed up the loading of the pages where pass through rates are low. Faster loading means more users continue their flow, and overall user engagement increases. It’s one of the most important things the front end can optimize.
Another thing that matters is the amount of visits by users. If that number grows, it means users enjoy the interface and are willing to return. This metric can help evaluate improvements to specific UX flow and encourage users to visit more frequently
You’re an active mentor and instructor at Outtalent, The Rolling Scopes School, Women in Tech, and GetMentor. How does mentoring beginner developers influence your own approach to frontend and architecture?
Mentoring helps you grow — by explaining development concepts to students and junior engineers, you often gain new perspectives on your own work and realize where you could have done things more efficiently. I’ve had several insights during mentoring sessions that led me to simplify certain elements in my own projects.
I’d even say that experienced professionals can learn from newcomers. Junior developers often take simpler approaches, resulting in less overloaded interfaces and fewer unnecessary complexities. They’re also less fixated on rigid rules and tend to be more creative — which can lead to excellent outcomes.
Has working on a product like this global service changed your perspective on teamwork and communication within international teams?
An international team makes a product stronger, as it brings together people with diverse cultural backgrounds, mentalities, and languages — which helps with localization and user experience across regions. In large organizations, responsibility shifts from individual contributors to the entire team, where everyone works toward a shared goal. When problems arise, the whole team gets involved in solving them.
Documentation also plays a critical role in large companies. In startups, issues can often be resolved through direct communication, but in corporations, the same information must be communicated to many stakeholders. That’s why detailed documentation is created at the start of every project — it aligns all stages of development and helps new team members quickly understand the context.
Looking ahead, what trends in frontend performance and optimization do you see as key for global video services?
There’s a common problem in mobile development today: delivering code to the end user takes much longer compared to the web. Any app update must go through App Store and Google Play reviews, followed by notifying users to install the update. As a result, weeks or even months can pass between writing code and users actually seeing the changes.
To reduce time to market, companies are increasingly moving logic and frontend components into mobile apps — essentially embedding web components inside them. This allows real-time content updates from the server saving time on publishing new version of the app. However, it introduces an extra layer — a container with external logic — which can make the app slower.
That’s why companies now think about optimization at the architectural stage. New architectural trends have emerged, such as hybrid mobile development, and microfrontends — where many smaller projects are combined into one.
There’s also a growing demand for developers who understand how mobile and web integrations work and can handle them efficiently.
