• 1 day left
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    Senior Quantitative Researcher

    Swissblock Technologies • Full 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...
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  • 1 day left
    Remote · Singapore — Hybrid Posted: Mar 8, 2026
    Job description
    Crypto dot com is hiring a Senior Quality Assurance Automation Engineer to join its blockchain engineering team in Singapore. The team builds and maintains scalable applications that support venture projects adjacent to the company’s core platform, covering components across frontend UI, backend services, and infrastructure. This role focuses on designing...
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  • Closes today
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    Rust Engineer - Platform

    Keyrock • Full 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...
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  • 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.

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    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.
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  • 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.
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  • 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.
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  • 14 days left
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    Security Engineer — Rust & Security

    Parity • Full Time

    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...
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  • 9 days 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...
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  • 9 days 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,...
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  • 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.
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