I built an all-in-one PDF Scanner & Vault app solo in Kotlin — Lihenium is now live on Play Store!

Hey DEV community! I'm Abhishek, a solo Android developer from Bihar, India. After months of late-night coding, I launched my app Lihenium: Scan PDF & Vault on Google Play Store! 🤔 Why I Built It I was frustrated using 5 different apps just to scan, edit, manage, compress and lock my documents. So I built one app that does everything — offline-first, private by default. 🛠️ Tech Stack Kotlin + Jetpack Compose OpenCV for smart document corner detection Room Database for local storage CameraX for scanning ML Kit for OCR 📱 Core Features ✂️ PDF Tools: Merge, split, sign, OCR & watermark 📷 QR Scanner & Generator 📄 Smart Document Scanner with auto-crop 🔒 Secure Vault with biometric lock 📁 Doc Library with folders & tags 🖼️ Passport photo maker & background remover ☁️ Optional Google Drive backup 💪 Biggest Challenges as Solo Dev Integrating OpenCV efficiently without bloating the APK Handling 10,000+ images without OOM crashes Keeping the final APK at just 18MB wit