Title: Blockchain Developer
Quick Summary
ChainHarbor Labs is hiring a Blockchain Developer to design, implement, and harden on-chain smart contracts and supporting services. You will write secure, gas-efficient code, create thorough tests and audits, and collaborate with product, design, and security to deliver features that are safe for mainnet. We welcome motivated entry-level engineers and recent graduates alongside experienced developers who enjoy mentorship, threat modeling, and measurable impact.
Project Category or Industry
Web3 — decentralized finance and consumer on-chain applications
Type
Full-time employment
Experience Level
Entry-level to mid-level, with structured mentorship and growth paths for freshers who demonstrate strong fundamentals and portfolio work (hackathons, open-source contributions, or side projects)
Duration
Permanent role
Location
Remote-first across the Americas, EMEA, and APAC with a minimum 4-hour overlap between 09:00–18:00 UTC; optional hub days in Lisbon and Singapore
Salary
USD 72,000–120,000 base depending on location and experience, plus annual bonus eligibility and optional equity or token grants subject to jurisdiction
Payment Mode
Monthly payroll via bank transfer; contractor arrangements available where local employment is not supported
Hiring Company Name
ChainHarbor Labs
Required Skills or Tools
Strong programming fundamentals and curiosity about security. Familiarity with smart contract languages such as Solidity or Rust, an understanding of EVM or Solana execution models, and comfort with writing comprehensive tests and scripts. Clear written communication and a bias toward simplicity and safety are essential.
Project Details
Project Description
You will help design and ship contracts that power DeFi and consumer on-chain experiences, from token mechanics and upgradeable modules to allowlisting, treasury flows, and cross-chain interactions. The work blends greenfield protocol components with careful iteration on existing contracts, emphasizing defense-in-depth, auditability, and an excellent developer experience for integrators. The purpose is to deliver features that are secure by default, economical to run, and easy to extend as the product evolves.
Core Responsibilities and Expected Deliverables
Implement production-grade smart contracts with clear interfaces, events, and access controls; optimize for gas and readability.
Author exhaustive unit, integration, property-based, and fuzz tests; define invariants and negative cases.
Build deployment scripts, upgrade procedures, and emergency controls; maintain migration and verification steps for explorers.
Collaborate with security on threat models, static analysis, and remediation; coordinate external audits and bug bounty responses.
Integrate on-chain components with off-chain services (indexers, relayers, wallets) and contribute to SDKs for partners.
Deliver concise documentation: protocol specs, risk notes, runbooks, and changelogs supporting safe mainnet releases.
Required Experience and Preferred Qualifications
Foundation in algorithms, data structures, and cryptographic primitives at a conceptual level; understanding of reentrancy, access control, overflow, and signature verification pitfalls.
Demonstrated work such as hackathon submissions, testnet deployments, or open-source pull requests.
Nice to have: experience with upgrade patterns (UUPS or Transparent), role-based access control, permit flows (EIP-2612), EIP-712 typed data, or cross-chain messaging.
Familiarity with gas profiling, storage layout, and economic analysis of protocol incentives.
Industry certifications are welcome but not required.
Tools or Platforms to Be Used
EVM stack: Solidity, Foundry (forge/anvil), Hardhat, OpenZeppelin libraries, Slither, Echidna, Mythril; deployment and verification via forge scripts or Hardhat tasks
Rust/Solana stack (as applicable): Rust, Anchor, Solana Program Library, local validator, Anchor tests
Indexing and off-chain: The Graph or Subsquid, simple relayers or Cloud Functions for automation, wallet integrations (WalletConnect)
Observability: Tenderly or Blockscout for simulation and tracing, on-chain monitors and dashboards for key metrics
Collaboration: GitHub for reviews, Notion for specs and RFCs, Jira for tracking
Language Requirement
English is required for daily collaboration; additional languages are a plus.
Communication Style
Asynchronous-first via Slack and GitHub with weekly Zoom stand-ups, design reviews, and security roundtables. Architecture and protocol decisions are documented in short RFCs with clear rationale and risk sections.
Time Commitment or Working Window
Approximately 40 hours per week with flexible scheduling; core collaboration windows target late morning to late afternoon UTC. Coordinated mainnet releases may require brief, planned overlaps outside core hours.
Payment Terms
Monthly salary with annual performance review and bonus eligibility. For contractors, milestone-based deliverables with biweekly invoicing and net-15 terms.
Evaluation Criteria
A short coding exercise implementing a safe, testable contract with invariants and gas considerations
Review of portfolio code or public repositories, including tests and documentation quality
Live pairing session on threat modeling and remediation of a vulnerable snippet
Communication clarity, ownership, and collaboration assessed through interviews and references
Other Requirements
Standard NDA upon offer acceptance, identity verification, and reference checks compliant with local laws. Security, privacy, and compliance training during onboarding, including guidance on responsible disclosure and key management. Light-touch time tracking for contractors to support accurate invoicing.
About the Company
ChainHarbor Labs is a remote-first product and protocol studio focused on building trustworthy, human-centered Web3 experiences. Founded in 2020, we combine security-first engineering with pragmatic product thinking to ship features that people actually use. Our teams operate across Europe and Asia with collaboration hubs in Lisbon and Singapore. Learn more at https://chainharborlabs.com or contact careers@chainharborlabs.com.