Infinite Images

Browse a massive, ever-growing collection of high-quality photos powered by the Unsplash API — with seamless infinite scrolling, offline-first data delivery, and a smart freshness system.

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APK Download

Download the latest release version of apk here

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📑 Table of Contents

• About the Project
• Key Features
• What I Built & Learned
• Tech Stack
• Architecture
• Getting Started
• Developer

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About the Project

Infinite Images is an Android portfolio app that lets users browse thousands of photos from Unsplash with a smooth, paginated infinite scroll. The app is built around an offline-first strategy — data is fetched from the network, persisted locally, and served from the local database as the primary source of truth. A custom freshness mechanism and pull-to-refresh keep the content up to date without unnecessary network calls.

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Key Features

• ♾️ Infinite scroll — pages load automatically as the user scrolls
• 📶 Offline-first — image metadata is available without internet; only image rendering requires connectivity (per Unsplash policy)
• 🕐 Smart data freshness — auto-refreshes from page 1 only when data is older than 24 hours
• 🔄 Pull-to-refresh — bypasses the freshness check and forces a fresh load from page 1
• 🖼️ Smooth image loading — powered by Coil with built-in caching

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What I Built & Learned

🗄️ Offline-First with Paging 3 + Room + RemoteMediator

• Local Room database is the single source of truth for the UI
• RemoteMediator handles fetching new pages from the Unsplash API, saving them to Room, which then drives the UI automatically
• When the local data runs out, the mediator transparently loads the next remote page and persists it

⏱️ Custom Data Freshness Logic

• On app start, the app checks the oldest entry in the local database
• If older than 24 hours → triggers a full refresh from page 1
• If within 24 hours → continues appending new pages without disrupting existing data

🔄 Pull to Refresh

• Overrides the freshness check entirely and forces reload from page 1
• Gives users manual control without waiting for the staleness threshold

🖼️ Image Loading Strategy (Coil + Unsplash Policy)

• Unsplash prohibits caching images locally for display
• Image metadata (title, author, dimensions, URLs) is cached in Room for offline access
• Images themselves are loaded via Coil; if the cache expires, a network connection is needed to reload

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Tech Stack

Layer	Technology
Language	Kotlin 2.0.21
UI	Jetpack Compose
Architecture	MVVM + Repository Pattern
Pagination	Paging 3 (with RemoteMediator)
Local DB	Room
Networking	Retrofit
Image Loading	Coil
API	Unsplash API
Min SDK	26
Target / Compile SDK	36
AGP	8.10.1
Gradle	8.11.1
Java	21

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Architecture

UI Layer (Jetpack Compose)
        │
        ▼
ViewModel (StateFlow + Paging3 Flow)
        │
        ▼
Repository
   ├── Local Source  ◄──────────────── Primary source of truth (Room DB)
   └── Remote Source ─► RemoteMediator ─► Unsplash API ─► saves to Room

• ViewModel exposes a PagingData flow to the UI
• Repository coordinates local and remote sources
• RemoteMediator bridges Paging 3 with the remote API, triggering network calls only when local data is exhausted or stale

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Getting Started

Prerequisites

• Android Studio Meerkat or later
• Unsplash Developer API key → Create one here

Setup

1. Clone the repository

   git clone https://github.com/rahulstech/infinite-images.git
   cd infinite-images

2. Add your Unsplash API key
   In your local.properties file:

   UNSPLASH_ACCESS_KEY=your_access_key_here
   

3. Build & Run
   Open in Android Studio and run on a device or emulator (API 26+)

⚠️ Rate Limit Notice
This app uses the Unsplash Free tier which allows 50 requests per hour.
If pages stop loading mid-scroll, you have likely hit the rate limit — this is an API limitation, not a bug. Wait a while and scroll again to resume.

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Developer

Rahul Bagchi
Android Developer

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