• 8 days left
    Remote · Worldwide Posted: Mar 23, 2026
    Job description
    Ritual is building a blockchain execution layer designed for AI-native operations, combining distributed systems, crypto infrastructure, and AI model access into a unified network. Their stack includes a live private testnet and products enabling both on-chain and off-chain AI execution. This role sits at the core of scaling distributed infrastructure,...
  • 9 days left
    Calgary, Canada — On-site Posted: Mar 12, 2026
    Job description
    NDAX is a cryptocurrency exchange based in Canada focused on building digital asset trading infrastructure and blockchain-based financial services. The company operates an exchange platform and develops blockchain technology solutions within its engineering division. This role involves working as a Full Stack Blockchain Developer responsible for building and maintaining Ethereum-based...
  • 9 days left
    I

    Blockchain Developer — DAML / Canton

    IntellectEUFull Time

    Remote · Worldwide Posted: Mar 12, 2026
    Job description
    IntellectEU is an international technology company focused on digital finance, financial messaging, and emerging technologies. Since 2006 the company has worked with financial institutions on large-scale integrations, payment infrastructure, and digital asset platforms, including being a SWIFT service partner. Its engineering teams build distributed systems and blockchain infrastructure used in...
  • 9 days left
    Remote · Worldwide Posted: Mar 10, 2026
    Job description
    Risk Labs is the core development team supporting decentralized protocols including UMA and Across. UMA provides an optimistic oracle that records verifiable data on blockchains, while Across focuses on cross-chain interoperability using intent-based architecture. The Senior Solutions Engineer role works at the intersection of engineering, product, and partnerships to support...
  • 9 days left
    C

    Senior Blockchain Security Engineer

    CoinbaseFull Time

    Remote · United States Posted: Mar 10, 2026
    Job description
    Coinbase is a global cryptocurrency exchange and blockchain infrastructure company focused on expanding economic access through digital assets and onchain financial systems. The Senior Blockchain Security Engineer role sits within Coinbase’s Blockchain Security (BlockSec) team, which focuses on protecting funds, protocols, and wallet interactions across blockchain networks. This position operates...
  • 9 days left
    Y

    Backend Integrations Engineer

    Yield.xyzFull Time

    Remote · US - time zones Posted: Mar 10, 2026
    Job description
    Yield.xyz builds yield infrastructure for Web3 developers by aggregating staking, restaking, stablecoin, and DeFi yield opportunities across multiple blockchains into a unified API platform. The Backend Integrations Engineer role focuses on designing backend systems that connect Web2 infrastructure with blockchain-based financial protocols. This position operates as a remote role in...
  • 9 days left
    S

    Senior Quantitative Researcher

    Swissblock TechnologiesFull Time

    Remote · Switzerland - Remote Posted: Mar 8, 2026
    Job description
    Swissblock Technologies is a private investment firm focused on integrating cryptocurrency markets with cross-asset investment strategies. The firm manages systematic multi-strategy portfolios that combine digital assets with traditional financial markets using quantitative research and algorithmic trading systems. The Senior Quantitative Researcher will join the Systematic Crypto Group, where researchers transform...
  • 9 days left
    K

    Rust Engineer - Platform

    KeyrockFull Time

    Remote · Worldwide Posted: Mar 7, 2026
    Job description
    Keyrock is a digital asset market maker operating across more than 80 exchanges and working with a wide range of asset issuers. The company provides services across market making, options trading, high-frequency trading, OTC trading, DeFi trading desks, and digital asset management. The Rust Engineer – Platform role focuses on...
  • Difficulty - Medium
    Total Plays - 16
    Allowed Time - 10 sec
    Best time - 1.252 sec

    What is the most direct risk of “unbounded loops” in on-chain code?

    Tip: Click "Play" to reveal options and start playing.

    #A
    #B
    #C
    #D
    Explanation:
    Unbounded loops can make functions exceed block gas limits as state grows, permanently preventing execution—classic denial of service. This is common in airdrop distributions, iterating holders, or clearing arrays. Security interviews test this because it’s a real production failure: “worked in tests” but becomes uncallable at scale. Mitigations include batching/pagination and off-chain indexing.
  • Difficulty - Medium
    Total Plays - 14
    Allowed Time - 10 sec
    Best time - --

    Which bug class is most associated with incorrect upgradeable storage layout?

    Tip: Click "Play" to reveal options and start playing.

    #A
    #B
    #C
    #D
    Explanation:
    In upgradeable contracts, the proxy holds storage while the implementation code changes. If developers reorder variables or change types, storage slots map incorrectly—corrupting balances, roles, or critical pointers. This is a high-severity issue in audits. Interviewers expect candidates to mention append-only storage layout, storage gaps, and standards like EIP-1967 for proxy slots.
  • Difficulty - Medium
    Total Plays - 12
    Allowed Time - 10 sec
    Best time - 0.778 sec

    What is the core risk of using tx.origin for authorization?

    Tip: Click "Play" to reveal options and start playing.

    #A
    #B
    #C
    #D
    Explanation:
    tx.origin authorization can be bypassed if a user is tricked into calling an attacker contract, which then calls the target contract—tx.origin remains the user. This is a known insecure pattern in Ethereum security. Interviewers like it because it tests whether candidates understand call chains and why msg.sender + explicit access control is the correct boundary.
  • 6 days left
    P
    Remote · Worldwide Posted: Mar 4, 2026
    Job description
    Parity builds core blockchain infrastructure including Polkadot, Polkadot SDK, and Kusama. This contract-based, remote role sits within the Security Engineering team and focuses on strengthening security across decentralized systems and Rust-based software components. The Security Engineer will conduct deep manual and automated audits, write secure Rust code where required, and...
  • 1 day left
    Remote · Worldwide Posted: Mar 1, 2026
    Job description
    Veda builds DeFi infrastructure that enables financial platforms to launch on-chain yield products through enterprise-grade integrations. The protocol supports multiple large vault products and operates at multi-billion TVL scale with a global user base. This Smart Contract Engineer role focuses on Solidity development across vault systems, upgradeable proxy architecture, account...
  • 1 day left
    Remote · US Remote Posted: Mar 1, 2026
    Job description
    CertiK is a blockchain security company focused on audits, security research, and infrastructure protection across decentralized systems. The firm has audited thousands of Web3 projects and supports protocols securing large volumes of digital assets. This Junior Blockchain Security Engineer role sits within web3 security roles and supports smart contract audits,...
  • Difficulty - Medium
    Total Plays - 17
    Allowed Time - 10 sec
    Best time - 0.263 sec
    #A
    #B
    #C
    #D
    Explanation:
    immutable variables are assigned once (typically in the constructor) and then become read-only. They are stored in bytecode rather than regular storage slots, which can reduce gas compared to storage reads. This matters in Solidity interviews because immutables are common in optimized contracts (e.g., router addresses) and in secure configuration patterns.