Jonatas Martins

I’m Jonatas Martins, a Security Researcher at Spearbit since 2022 and Cantina Fellow focused on DeFi protocol security. I came from Web2 web/mobile engineering, which helps me audit systems from a builder’s perspective: understanding intended behavior, modeling how integrations fail, and identifying practical issues that matter in production.

My strongest areas are Solidity/EVM DeFi, lending markets, ERC4626/vault systems, AMMs/DEXs, cross-chain and token bridge flows, governance upgrades, protocol accounting, and integrations. Recently, I have also been expanding into Rust and AI security. My security work includes reviews for Uniswap, MakerDAO/Sky, Coinbase, Maple, Centrifuge, Morpho, Velodrome, and other DeFi protocols.

In 2024, I worked as a judge and triaged bug bounty programs in Cantina. Outside direct audits, I contributed to the 2023 Rewind, spoke at TrustX 2023 and DSS 2024, and worked on Certora Prover tooling through the Aave Grant Program.

I enjoy reviews where I can dig into how a protocol is supposed to work, think through how it can break, and focus on issues that would actually matter in production.

Core Expertise

• Solidity/EVM protocol security
• DeFi protocol design and implementation review
• Lending markets and collateralized debt systems
• ERC4626 vaults, yield vaults, and accounting edge cases
• AMMs, DEXs, swap logic, and routing/integration risk
• Cross-chain bridges, token bridge flows, and cross-chain oracles
• Governance, upgrade scripts, and deployment/configuration review
• Protocol accounting, rounding, precision loss, and invariant breaks
• Rust/Solana security

Public Contributions

• Contributor to 2023 Rewind, ranked #2 in the incident writing contest.
• Speaker at TrustX 2023 on Ethereum Smart Contract Auditor’s 2023 Rewind
• Speaker at DSS 2024 on Leveraging knowledge to trasition between blockcain stacks.
• Contributor to Certora Prover Tools — Aave Grant Program, including work related to Aave Starknet Bridge and Aave Token V3 verification tooling.
• Cantina judge and bug bounty triager in 2024/25.