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← Back to selected workCORE DEFENSE / ANDROID CASE STUDY

Device security,
made understandable.

An Android defender app bringing device signals, security insights, and subscription features into one native experience.

MY ROLE
Full Android development
CONTEXT
Galaksion · Mobile product
PRODUCT
Device security & insights
CORE STACK
Kotlin · Jetpack Compose
01 / PRODUCT & OWNERSHIP

Device signals,
turned into a clear next step.

Core Defense helped users review their device’s security posture through a security score, app signals analysis, usage and cache insights, and a device settings overview. The interface connected the summary score to specific items that may need attention.

I owned the Android development: architecture, Compose UI, on-device analysis, subscription integrations, analytics, signing, and Google Play release work.

The product is no longer in active development. The screenshots and walkthrough show the application as shipped, running on a Pixel 9 Pro XL.

02 / THE APPLICATION

Insights, explained.
Premium, integrated.

The device overview, score breakdown, and subscription experience. Open any capture to inspect it.

Core Defense dashboard with security score, device statistics and insight tools
Device overviewA summary score alongside app, usage, cache, and settings insights.
Security score breakdown sheet with review categories and their score contributions
Score breakdownA bottom sheet connecting the score to reviewable items.
Core Defense Premium screen with monthly, yearly and lifetime plan options
Subscription experienceMultiple plans with pricing presented inside the native interface.
03 / DEVICE WALKTHROUGH

See the experience.

A short walkthrough of the dashboard, score explanation, and Premium plan selection — recorded directly from the Android app.

Recorded on Pixel 9 Pro XL · No audio.

  1. Review the device dashboard.
  2. Open the Security Score breakdown.
  3. Explore the Premium plans.
  4. Return to the device overview.
04 / ENGINEERING CONTRIBUTIONS

Signals, subscriptions,
and shipping.

The Android work spans device analysis, monetization, product measurement, and release delivery.

01 / ON-DEVICE ANALYSIS

Make the score explainable.

I developed a custom on-device scoring engine using 20+ behavioral and permission-based signals on a 0–100 scale. The product surfaces app signals and device settings as reviewable items, with a breakdown behind the summary score.

Kotlin · Device signals · Compose

02 / MONETIZATION

Connect plans to purchases.

I implemented multi-plan monetization with Google Play Billing, purchase validation integrations, and purchase-token deduplication. Subscription and regional pricing work improved conversion by 15–25%.

Google Play Billing · Purchase validation · Regional pricing

03 / ANALYTICS & ATTRIBUTION

Measure the product funnel.

I built an analytics abstraction supporting Firebase and AppMetrica, structured funnel events, and experiments through Remote Config. Attribution integrations used the Install Referrer API and server-side postbacks.

Firebase · AppMetrica · Remote Config · Install Referrer

04 / RELEASE OWNERSHIP

Carry the app through release.

My scope covered the Android architecture and implementation through signing, store requirements, Google Play publication, and post-release iteration. I also integrated remote scanning APIs with hash verification and polling-based result retrieval.

Architecture · Signing · Google Play · API integration

05 / WHAT THIS PROJECT DEMONSTRATES

Android engineering
across the whole product.

Core Defense combined a native interface, device-level signals, subscriptions, analytics, and release delivery. It demonstrates my responsibility for the complete Android implementation and the product infrastructure around it.

KotlinJetpack ComposeCoroutines & FlowGoogle Play BillingFirebaseAppMetricaRemote Config
LET’S TALK ANDROID

Have a product
to build↗

Evgenii Fedin · Android Engineer

More work ↗Résumé PDF ↓LinkedIn ↗