Web3 / Blockchain DApp Developer – Wallet & Smart Contract Integration

Company Description Solidity Labs is a specialized blockchain development firm providing full-stack, custom solutions and smart contract auditing services. The team focuses on secure, dynamic, on-chain architectures for digital products, including tokens, DAOs, and decentralized financial instruments. Solidity Labs also builds enterprise Web3 solutions for brands, startups, and Fortune 500 companies, emphasizing scalability and security. Core engagements include token creation and tokenomics, layer two solutions, exchanges and cross-chain compatibility, staking and yield protocols, asset indexing and redeemability, and end-to-end DApp buildouts. Candidates joining Solidity Labs can expect to work on cutting-edge blockchain initiatives with a focus on high-impact, production-grade systems.
Role Description This is a remote contract role for a Web3 / Blockchain DApp Developer – Wallet & Smart Contract Integration. In this role, you will design, develop, and maintain decentralized applications that integrate with various blockchain networks, wallets, and smart contracts. You will implement and optimize wallet connection flows, handle transaction lifecycle management, and ensure secure interaction with on-chain assets and protocols. Day-to-day tasks include building front-end and back-end components for DApps, integrating smart contracts, troubleshooting and debugging blockchain interactions, and collaborating with product and security teams to refine specifications and user flows. You will also participate in code reviews, contribute to documentation and best practices, and stay current on emerging Web3 standards, tooling, and security guidelines.
Qualifications
We are looking for an experienced Web3 / Blockchain DApp Developer to work alongside our existing ASP.NET MVC/.NET backend developer.
Our existing .NET developer is responsible for the core backend, database, business logic, admin panel and compensation/referral system.
We need a Web3 specialist who can take complete responsibility for the DApp, decentralized wallet, blockchain, smart contract and crypto transaction integration layer and integrate it seamlessly with our existing .NET backend.
Key Responsibilities
• Design the overall DApp and blockchain integration architecture
• Implement wallet-based registration, login and authentication
• Integrate MetaMask, Trust Wallet, WalletConnect and other compatible wallets
• Implement secure wallet signature verification
• Integrate wallet-based registration with the existing .NET referral system
• Support sponsor/referral identification and binary placement parameters
• Synchronize wallet identity and blockchain transactions with the .NET backend
• Develop and integrate required smart contracts
• Implement crypto payment/deposit/joining functionality
• Implement withdrawal functionality
• Handle on-chain transaction verification and confirmation
• Integrate blockchain events/transactions with backend APIs and database records
• Deploy and test the complete system on testnet before production/mainnet deployment
• Work closely with our existing .NET developer throughout implementation
Wallet & DApp Integration
The platform should support:
• Connect Wallet
• MetaMask
• Trust Wallet
• WalletConnect
• Other compatible decentralized wallets
• Wallet-based signup/login
• Message/signature-based wallet authentication
• Network/chain detection
• Wallet-address validation
• Secure session management
Users’ private keys or seed phrases must never be requested, transmitted or stored by the platform.
Referral System Integration
Our existing .NET backend will manage the main referral and compensation logic.
The Web3 developer will be responsible for integrating wallet-based registration with this system, including:
• Sponsor/referral identification
• Binary placement parameters where applicable
• Referral-link integration with wallet registration
• Secure transfer of registration/referral information to the .NET backend
• Synchronization between connected wallet, user account and backend records
Detailed compensation-plan logic will be shared with the selected developer as required.
Crypto Payment / Joining Integration
The developer should be able to design and implement a secure crypto payment flow including:
• ERC-20/token payments
• USDT/USDC or other supported token integration
• Token allowance/approval transactions where required
• Package/joining payment through connected wallets
• Transaction signing
• On-chain payment verification
• Transaction hash recording
• Blockchain confirmation monitoring
• Pending/failed/reverted transaction handling
• Duplicate transaction prevention
• Backend/API synchronization after successful payment
Withdrawal Integration
The developer should design a secure and scalable withdrawal architecture, including:
• Withdrawal requests
• Wallet-address validation
• Backend balance/eligibility verification
• Blockchain transaction execution
• Transaction-status monitoring
• Transaction hash storage
• Gas/transaction-fee handling
• Failed/reverted transaction management
• Prevention of duplicate or unauthorized withdrawals
The developer should also be capable of recommending the appropriate architecture for withdrawals, treasury management and smart-contract interaction based on security and scalability requirements.
Smart Contract Development
Depending on the final architecture, responsibilities may include:
• Solidity smart-contract development
• Smart-contract testing
• Smart-contract deployment
• ERC-20 integration
• Contract interaction from the DApp
• Blockchain events and event monitoring
• Role-based/access-control implementation
• Gas optimization
• Security best practices
• Testnet and mainnet deployment
.NET / Backend Integration
This is an important requirement.
The selected developer must be capable of working closely with our existing .NET developer to establish reliable communication between the Web3/DApp layer and the centralized backend.
Experience with the following will be highly valuable:
• ASP.NET MVC / ASP.NET Core integration
• REST APIs / Web APIs
• Webhooks
• JSON-RPC
• Nethereum
• Blockchain RPC providers
• Smart-contract event listeners
• Event-driven architecture
• SQL/database synchronization
• On-chain/off-chain transaction reconciliation
Required Technical Skills
Strong hands-on experience with:
• Web3 development
• Blockchain/DApp development
• Solidity
• EVM-compatible blockchains
• JavaScript / TypeScript
• ethers.js and/or viem
• WalletConnect
• MetaMask
• Trust Wallet
• Smart contracts
• ERC-20 tokens
• RPC providers
• Blockchain transaction lifecycle
• Wallet signature verification
• Smart-contract interaction
• Git/GitHub
Experience integrating Web3 with ASP.NET MVC, ASP.NET Core or other traditional backend systems will be a major advantage.
Security Knowledge Required
The developer should have a strong understanding of:
• Non-custodial wallet architecture
• Private-key security
• Signature verification
• Replay-attack prevention
• Smart-contract access control
• Common smart-contract vulnerabilities
• Reentrancy protection
• Treasury-wallet security
• Multisig architecture
• RPC/API security
• Transaction validation
• Duplicate-payment prevention
• On-chain/off-chain synchronization
Expected Deliverables
The selected developer will be expected to deliver:
1. DApp + .NET integration architecture
2. Wallet connection module
3. Wallet-based signup/login system
4. Referral/wallet registration integration
5. Crypto payment/joining integration
6. On-chain payment verification
7. Withdrawal integration
8. Required smart contracts
9. Blockchain-to-.NET API integration
10. Transaction/event monitoring
11. Testnet deployment and testing
12. Production/mainnet deployment support
13. Source code
14. Technical documentation
15. Deployment/configuration documentation
16. Technical support and coordination with our existing .NET developer
Ideal Candidate
We are specifically looking for someone with real hands-on experience building production Web3 applications, rather than only theoretical blockchain knowledge.
Previous experience with any of the following will be highly preferred:
• Production DApps
• Web3 fintech platforms
• Crypto payment systems
• Wallet-based membership platforms
• Referral/affiliate platforms
• DeFi applications
• Token-based platforms
• Smart-contract payment systems
• Web3 + centralized backend integrations
How to Apply
Please se

Work arrangement
Yes