Contact person: Business Client

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Location: Mumbai, India

Budget: Recommended by industry experts

Time to start: As soon as possible

Project description:
"1. Project Overview

We are seeking an experienced and security-focused mobile developer or development team to build a non-custodial cryptocurrency wallet application for Android (APK). The final product must replicate the core functionality, intuitive UX/UI, and high security standards of leading wallets like Trust Wallet.

Goal: Develop a fully functional, secure, multi-chain mobile wallet from scratch.
Target Platform: Android (APK) only for initial launch.
Wallet Type: Non-Custodial (user retains full control of private keys/seed phrase).

2. Core Functional Requirements

The wallet must include the following minimum viable product (MVP) features:

A. Wallet Management

Create/Import Wallet: Implement secure wallet generation based on industry standards (e.g., BIP39/BIP44). Must support 12/24-word seed phrase generation and import (mnemonic phrase).

Balance Display: Real-time display of multi-chain asset balances (coins and tokens) and total portfolio value in a fiat currency (e.g., USD, EUR).

Asset Support: Initial support for Bitcoin (BTC), Ethereum (ETH), and major EVM-compatible chains (e.g., BNB Smart Chain, Polygon).

B. Transactions

Send/Receive: Ability to send and receive crypto assets.

QR Code Scanner: Integrated scanner for easy payment address input.

Transaction History: Clear, detailed history of all incoming and outgoing transactions with links to relevant block explorers.

Gas/Fee Estimation: Accurate, real-time calculation and display of transaction fees with options for users to adjust gas limits (for EVM chains).

C. Web3 & DApp Interaction

Integrated DApp Browser: A secure, built-in browser environment capable of connecting to decentralized applications (dApps) using protocols like WalletConnect or equivalent Web3 standards.

Transaction Signing: Ability to securely sign messages and approve transactions initiated via the DApp browser without exposing the private key.

3. Mandatory Security Requirements

Security is the absolute highest priority. The freelancer must demonstrate expertise in modern mobile and blockchain security best practices.

Private Key Storage: Private keys and seed phrases must be encrypted and stored only on the user's device, ideally using Android's Secure Enclave or Keystore. Keys must never leave the device or be stored on external servers.

Biometric Authentication: Mandatory integration of Fingerprint/Face ID recognition for opening the wallet and authorizing transactions.

Seed Phrase Backup: Clear, non-screenshot-friendly UI flow for secure seed phrase backup.

Code Security: Comprehensive code auditing and prevention against common vulnerabilities like replay attacks and double-spending.

4. Technical Stack & Expertise

Candidates should be proficient in the following technologies:

Mobile Development: Experience with Kotlin/Java (Native Android) or React Native/Flutter (if cross-platform is used, final output must be a highly optimized Android APK).

Blockchain Integration: Expert knowledge of integrating with multiple blockchain networks (BTC, ETH/EVM).

Libraries: Experience with blockchain interaction libraries (e.g., [login to view URL], [login to view URL], or native blockchain SDKs/bindings).

Cryptography: Strong understanding of cryptographic standards (e.g., ECDSA) and wallet standards (BIP39, BIP44).

5. Deliverables & Application Requirements

Deliverables

Complete, well-documented source code (clean, commented, and organized).

API/Node layer documentation (if a dedicated backend is required for indexing/data fetching).

A finalized, debug-free Android APK file ready for testing." (client-provided description)