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You will get Smart Contract & DApp Development — Solidity + Hardhat + React
Project details
Need a secure smart contract or full-stack DApp built by a developer who understands both blockchain and traditional backend? I build production-ready Solidity contracts and decentralized applications with security-first approach.
What you'll get:
— Solidity smart contracts (ERC-20, ERC-721, ERC-1155, custom logic)
— OpenZeppelin v5.x security standards and access control
— Hardhat development environment with automated testing
— Gas optimization for lower transaction costs
— React/Next.js frontend with Web3 wallet integration (MetaMask, WalletConnect)
— Ethers.js/Wagmi for blockchain interaction
— Multi-chain deployment (Ethereum, Polygon, BSC, Arbitrum, Base)
— Contract verification on Etherscan/block explorer
— Full test coverage with unit and integration tests
Contract types I build:
— Token contracts (ERC-20 with vesting, staking, governance)
— NFT contracts (ERC-721/1155 with minting, royalties, metadata)
— DAO governance (proposal, voting, treasury management)
— DeFi protocols (staking pools, yield farming, token swap)
— Custom business logic (escrow, marketplace, access control)
Send me your requirements and I'll provide a technical proposal within 24 hours.
What you'll get:
— Solidity smart contracts (ERC-20, ERC-721, ERC-1155, custom logic)
— OpenZeppelin v5.x security standards and access control
— Hardhat development environment with automated testing
— Gas optimization for lower transaction costs
— React/Next.js frontend with Web3 wallet integration (MetaMask, WalletConnect)
— Ethers.js/Wagmi for blockchain interaction
— Multi-chain deployment (Ethereum, Polygon, BSC, Arbitrum, Base)
— Contract verification on Etherscan/block explorer
— Full test coverage with unit and integration tests
Contract types I build:
— Token contracts (ERC-20 with vesting, staking, governance)
— NFT contracts (ERC-721/1155 with minting, royalties, metadata)
— DAO governance (proposal, voting, treasury management)
— DeFi protocols (staking pools, yield farming, token swap)
— Custom business logic (escrow, marketplace, access control)
Send me your requirements and I'll provide a technical proposal within 24 hours.
Programming Languages
HTML & CSS, TypeScriptCoding Expertise
Cross Browser & Device CompatibilityWhat's included
| Service Tiers |
Starter
$200
|
Standard
$400
|
Advanced
$600
|
|---|---|---|---|
| Delivery Time | 7 days | 14 days | 21 days |
Number of Revisions | 0 | 0 | 0 |
Design Customization | - | - | - |
Content Upload | - | - | - |
Responsive Design | - | - | - |
Source Code | - | - | - |
Optional add-ons
You can add these on the next page.
Additional smart contract
(+ 5 Days)
+$50
Multi-chain deployment
(+ 7 Days)
+$100
Security audit report
(+ 9 Days)
+$100Frequently asked questions
About Duong
Senior Backend Engineer | Spring Boot Microservices | CKAD Certified
Hanoi, Vietnam - 10:33 am local time
With 4+ years as a Backend Engineer & Technical Lead, I specialize in Java Spring Boot microservices for mission-critical systems. My core focus is Intelligent Transportation Systems (ITS), including real-time traffic monitoring, adaptive signal control, and Origin-Destination (OD) matrix analysis — systems that must run 24/7 with zero tolerance for downtime.
What I bring to your project:
- Backend: Java Spring Boot · Microservices · Apache Kafka · Redis · Elasticsearch · PostgreSQL · REST API
- DevOps & Cloud: Kubernetes (CKAD Certified) · Docker · AWS (Cloud Practitioner Certified) · Jenkins · Ansible · Prometheus · Grafana · CI/CD
Key results from production systems:
- Reduced system latency by 10% through Redis caching optimization
- Improved query response speed by 20% with Elasticsearch integration
- Enhanced application performance by 30% using ELK + APM monitoring
- Processed millions of events/day using Apache Kafka and NiFi pipelines
- Led a team of 5 engineers for 2+ years delivering ITS solutions
I also mentor engineers at Viettel Digital Talent 2025 & 2026 in backend architecture and software development best practices.
BS in Computer Engineering — Hanoi University of Science and Technology (2022)
Let's talk about your backend challenges.
Steps for completing your project
After purchasing the project, send requirements so Duong can start the project.
Delivery time starts when Duong receives requirements from you.
Duong works on your project following the steps below.
Revisions may occur after the delivery date.
Requirements & architecture
Review your project scope, define contract architecture, data structures, and function specifications. Deliver a technical design document for your approval before coding.
Smart contract development
Write Solidity contracts using OpenZeppelin v5.x standards. Implement business logic, access control, events, and gas optimizations. Deploy to testnet for review.