Hellobot is a saju / love / tarot chatbot app by Thingsflow with 800K MAU and 1M+ cumulative downloads, serving personalized readings through character-based chatbots.
Client
Thingsflow
Year
2020 – 2023
Scope
Android Development (solo)
Platform
Android · Kotlin · Retrofit · RxJava · MVVM
The Challenge
The main screen suffered from 3-second+ loading delays, SQLite-based chat sync was fragile at scale, large-screen devices (foldables / tablets) hit OOM crashes, the payment funnel had drop-off issues, deeplink entry points were fragmented, and release lead-time was too long.
Our Solution
Re-architected the home with a single ConstraintLayout (collapsing nested RecyclerViews) and maximized ViewHolder reuse via a shared ViewPool; migrated chat persistence from SQLite to Room with a server-authoritative sync design; applied WindowSizeClass-based adaptive layouts and image downsampling for large screens; implemented subscription via BillingSDK and unified deeplinks through a single SchemeActivity entry point; built a GitHub Actions CI/CD pipeline with Detekt custom rules.
Results
Cut home loading time by ~3 seconds (reducing drop-off), lifted paid conversion by 10% through payment-funnel improvements, drove deeplink-related crashes from ~10/month to zero, eliminated 100% of large-screen OOM crashes, and shortened release lead-time by 80% with CI/CD and automated review.