Flash Protocol — Android

Cross-chain crypto payments for Android — scan a QR, pick your chain, pay in any token. The receiver gets USDC on their preferred chain. Powered by the Flash Protocol backend which aggregates quotes from 6 cross-chain providers across 70+ blockchain networks.

Features

QR Payments — Every user has a QR code. Scan it, enter an amount, pay from any chain.
Payment Links — Create a link with a fixed amount, share it anywhere.
70+ Chains — Pay from any supported chain; receives settle in USDC.
Multi-Wallet — Connect EVM wallets (MetaMask, Trust, Rainbow, Coinbase) and Solana wallets via Reown AppKit.
Best-Price Routing — Aggregates quotes from 6 providers, picks the cheapest route automatically.
Dark Mode — System/Light/Dark with persistent preference.
Onboarding — First-launch walkthrough.
Deep Linking — flashpay:// custom scheme + https://flash-protocol.vercel.app/pay/ universal links.

Supported Networks

Payments are supported across 70+ blockchain networks via the Flash Protocol backend:

EVM: Ethereum, Arbitrum, Optimism, Base, Polygon, BSC, Avalanche, Linea, Scroll, zkSync Era, and more.
Non-EVM: Solana, Cosmos (via IBC), Tron, TON, Starknet.
Bitcoin: Bitcoin, Litecoin.

Liquidity Providers

Quotes are aggregated from 6 cross-chain providers:

Provider	Type
LI.FI	Aggregator
Rango Exchange	Aggregator
Rubic	Aggregator
Symbiosis	Liquidity Protocol
Circle CCTP	Bridge Protocol
NEAR Intents	Intent Network

Tech Stack

Layer	Technology
Framework	Expo SDK 54, Expo Router v6 (file-based routing)
Runtime	React Native 0.81, React 19
Wallet	Reown AppKit v2 + Wagmi v3 + Viem v2 (EVM), Solana adapter
Styling	NativeWind v4 (Tailwind CSS for RN), Tailwind v3
Typography	Inter via `@expo-google-fonts/inter`
State	Zustand v5 (client), TanStack React Query v5 (server)
HTTP	Axios v1 with `x-wallet-address` header interceptor
QR	`react-native-qrcode-svg` (generation), `expo-camera` (scanning)
Animations	`react-native-reanimated` v4: Layout animations, gesture-driven bottom sheets
Testing	Jest v30, ts-jest v29
Language	TypeScript 5.9, React Compiler enabled

Prerequisites

Node.js ≥ 18
npm (package manager)
Android Studio with Android SDK (API 24+)
Java 17+ (for Gradle)
A physical Android device or emulator

Getting Started

1. Clone and install

git clone git@github.com:HoomanBuilds/flash-protocol-android.git
cd flash-protocol-android
npm install

2. Environment variables

Create .env.local in the project root:

EXPO_PUBLIC_REOWN_PROJECT_ID=your_reown_project_id

Get a project ID from Reown Cloud.

3. Run on Android

# Build native code + start Metro bundler
npx expo run:android

Note: This project uses a development build, not Expo Go. The first run compiles the native Android project (~2-3 min). Subsequent runs are faster.

Other commands

npm test           # Run tests (Jest)
npx expo lint      # Run ESLint
npx tsc --noEmit   # Type check

Project Structure

app/                          # Expo Router screens
├── _layout.tsx               # Root: WagmiProvider > QueryClient > AppKit > Stack
├── onboarding.tsx            # First-launch walkthrough
├── payment.tsx               # Payment flow (chain/token select → quotes → execute)
├── create-link.tsx           # Create payment link
├── transaction-status.tsx    # Tx polling + success/failure UI
└── (tabs)/
    ├── _layout.tsx           # Bottom tab bar (Home, Scan, Receive, Activity, Settings)
    ├── index.tsx             # Home — wallet status, recent txs, feature carousel
    ├── send.tsx              # QR scanner (expo-camera)
    ├── receive.tsx           # QR code display + share
    ├── activity.tsx          # Transaction history feed
    └── settings.tsx          # Receive chain prefs, theme, wallet info

config/
├── appkit.ts                 # Reown AppKit setup (EVM + Solana adapters, network discovery)
└── reown.ts                  # Project ID + app metadata

services/api/
├── client.ts                 # Axios instance (base: flash-protocol.vercel.app, 30s timeout)
├── chains.ts                 # getChains(), getTokens()
├── quotes.ts                 # getQuotes()
├── transactions.ts           # initiateTransaction(), submitHash(), getReceipt(), getHistory()
├── profile.ts                # getProfile(), updateProfile(), getReceiverProfile()
├── paymentLinks.ts           # getPaymentLink(), createPaymentLink(), listPaymentLinks()
└── price.ts                  # getPrice()

hooks/
├── useChains.ts              # Fetch chains with optional hasUSDC/type filters + sorting
├── useTokens.ts              # Fetch tokens for a specific chain
├── useQuotes.ts              # Fetch cross-chain quotes with 30s polling
├── useTransaction.ts         # Full tx lifecycle: initiate → submit hash → poll receipt
├── useProfile.ts             # Fetch/update user profile, syncs to Zustand
├── useUSDCToken.ts           # Resolve USDC token address for a chain
├── use-dark.ts               # Dark mode hook
├── use-theme-color.ts        # Theme-aware color resolution
├── use-color-scheme.ts       # System color scheme detection
└── use-color-scheme.web.ts   # Web-specific color scheme

stores/
├── wallet.ts                 # address, isConnected
├── payment.ts                # Full payment flow state
├── profile.ts                # User profile cache
└── theme.ts                  # Theme mode, persisted to AsyncStorage

components/
├── payment/
│   ├── chain-selector.tsx    # Searchable chain picker (grouped by type, popular pinned)
│   └── token-selector.tsx    # Token picker for selected chain
└── ui/
    ├── bottom-sheet.tsx      # Gesture-driven bottom sheet (Reanimated + GestureHandler)
    ├── pressable-scale.tsx   # Pressable with scale animation + optional haptics
    ├── toast.tsx             # Toast notification system
    ├── skeleton.tsx          # Shimmer loading placeholders
    ├── icon-symbol.tsx       # SF Symbols → Material Icons mapping
    ├── illustrations.tsx     # Inline SVG empty-state illustrations
    ├── onboarding-illustrations.tsx
    ├── network-banner.tsx    # Offline/connectivity banner
    └── collapsible.tsx       # Expandable sections

lib/
├── address.ts                # Wallet address validation + formatting
├── amount.ts                 # Token amount conversion (human ↔ raw units)
├── clipboard.ts              # Copy-to-clipboard utility
└── solana.ts                 # Solana-specific helpers

utils/
└── linking.ts                # Deep link parser (flashpay:// + universal links)

constants/
├── theme.ts                  # Color palette, semantic colors
└── usdc.ts                   # USDC contract addresses per chain

types/
└── api.ts                    # TypeScript interfaces (Chain, Token, Quote, Transaction, etc.)

__tests__/
├── address-validation.test.ts
├── amount.test.ts
├── deep-link.test.ts
└── stores.test.ts

Payment Flow

flowchart TD
    A["Scan QR / Open Payment Link"] --> B{"Payment Link or P2P?"}
    B -->|"Payment Link"| C["Fetch link details (amount, chain, wallet)"]
    B -->|"P2P (QR Scan)"| D["Fetch receiver profile (preferred chain/token)"]
    C --> E["Select Pay-From Chain & Token"]
    D --> E
    E --> F["Fetch Quotes (POST /api/quotes)"]
    F --> G["Initiate Transaction (POST /api/transactions/initiate)"]
    G --> H["Execute via Wallet (wagmi useSendTransaction)"]
    H --> I["Submit Tx Hash (PATCH /api/transactions/id/hash)"]
    I --> J["Poll Receipt every 5s (GET /api/transactions/id/receipt)"]
    J --> K{"Status?"}
    K -->|"Completed"| L["✅ Success Screen"]
    K -->|"Failed"| M["❌ Failure Screen"]
    K -->|"Pending"| J

API

All API calls go through https://flash-protocol.vercel.app.

Authentication: No sessions or JWT — wallet address is sent via x-wallet-address header, auto-injected by the Axios interceptor.

Method	Endpoint	Auth	Description
`GET`	`/api/chains`	No	Supported chains (`?hasUSDC=true` to filter)
`GET`	`/api/tokens?chainKey=X`	No	Tokens on a chain
`GET`	`/api/price?chainId=X&tokenAddress=X&symbol=X`	No	Token USD price
`POST`	`/api/quotes`	No	Cross-chain quotes
`POST`	`/api/transactions/initiate`	No	Log payment intent
`PATCH`	`/api/transactions/{id}/hash`	No	Submit signed tx hash
`GET`	`/api/transactions/{id}/receipt`	No	Poll tx status
`GET`	`/api/payment-links/{id}`	No	Payment link details
`GET`	`/api/profile/me`	Yes	User's receive preferences
`PUT`	`/api/profile/me`	Yes	Update receive chain/token
`GET`	`/api/profile/{wallet}`	Yes	Lookup another user's prefs
`GET`	`/api/transactions/history`	Yes	Sent + received tx feed
`GET`	`/api/payment-links`	Yes	User's payment links
`POST`	`/api/payment-links`	Yes	Create payment link

Deep Linking

Scheme	Example	Action
Custom	`flashpay://pay/{linkId}`	Open payment for a link
Custom	`flashpay://send?address={wallet}`	Open P2P payment to address
Universal	`https://flash-protocol.vercel.app/pay/{linkId}`	Open payment for a link (Android App Link)

Design

B&W aesthetic — Black, white, and gray palette only. No Material Design components.
Square corners — No border radius on cards, buttons, or inputs.
Inter font — Regular (400), SemiBold (600), Bold (700).
Dark mode — Full support via NativeWind dark: classes. Theme persisted to AsyncStorage.
Animations — Layout enter/exit via Reanimated, scale feedback on pressables, shimmer loading.

License

MIT

Name		Name	Last commit message	Last commit date
Latest commit History 49 Commits
.vscode		.vscode
__tests__		__tests__
app		app
assets/images		assets/images
components		components
config		config
constants		constants
hooks		hooks
lib		lib
scripts		scripts
services/api		services/api
stores		stores
types		types
utils		utils
.gitignore		.gitignore
README.md		README.md
app.json		app.json
babel.config.js		babel.config.js
eslint.config.js		eslint.config.js
global.css		global.css
jest.config.js		jest.config.js
metro.config.js		metro.config.js
nativewind-env.d.ts		nativewind-env.d.ts
package-lock.json		package-lock.json
package.json		package.json
tailwind.config.js		tailwind.config.js
tsconfig.json		tsconfig.json

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Flash Protocol — Android

Features

Supported Networks

Liquidity Providers

Tech Stack

Prerequisites

Getting Started

1. Clone and install

2. Environment variables

3. Run on Android

Other commands

Project Structure

Payment Flow

API

Deep Linking

Design

License

About

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Releases 1

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Flash Protocol — Android

Features

Supported Networks

Liquidity Providers

Tech Stack

Prerequisites

Getting Started

1. Clone and install

2. Environment variables

3. Run on Android

Other commands

Project Structure

Payment Flow

API

Deep Linking

Design

License

About

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Uh oh!

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Releases 1

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