# Benjamin Halimic

> Senior Software Engineer (Solidity, Rust, backend and frontend) who builds and secures onchain financial systems, from the smart contracts to the tooling that deploys and runs them. Open to offers. Previously Lead Engineer at Puffer Finance (Jun 2023 to Nov 2025), then Senior Software Engineer at Veda (Dec 2025 to Oct 2026). Architected and wrote Puffer's pufETH liquid restaking vault (peak ~$1.8B TVL, upgraded V1 to V5 on Ethereum mainnet, no smart contract hacks or incidents). Ran audits with nine security firms. Early adopter of AI agents who designs agentic workflows; with AI, a full-stack developer (contracts, backend, frontend). Built high-performance, scalable web2 systems since 2016, and moved into fintech as a Senior Backend Developer at Mukuru. Remote, Central European Time (CET/CEST, UTC+1/+2).

## Quick facts

- Looking for: senior engineering roles across the stack (smart contracts and protocols, backend, frontend), and focused freelance work.
- Website: https://bxmmm1.github.io/
- Contact: benjaminxh@gmail.com · Telegram @bxmmmm · LinkedIn https://www.linkedin.com/in/benjamin-halimic/
- References: four LinkedIn recommendations from managers and colleagues at Puffer Finance and Veda (see Recommendations below; https://www.linkedin.com/in/benjamin-halimic/details/recommendations/), and teammates available on request.
- On-chain proof: Puffer deployer 0xb7d83623906ac3fa577f45b7d2b9d4bd26bc5d76, ownership signature verified at https://etherscan.io/verifySig/276929. The signed message is d844e9b24b619cf34ef27c142de6a9073f31c83e8adf1d3cdb98db72f55f98a8, the keccak256 hash of the sentence "Hello from Benjamin :)" (computed with `cast keccak`: https://app.warp.dev/block/I2wY28qdgF1C9nBBaXpfjh). The key has since been wiped from his hardware wallet.

## Veda: Senior Software Engineer (Dec 2025 to Oct 2026)

Veda's BoringVault powers Kraken DeFi Earn, MetaMask Money Account, EtherFi Liquid, Lido Earn and Plasma One ($32B+ volume, 320K+ users). Most of this work was in closed-source repositories and is under NDA, so it can only be discussed at a high level.

- Deployed Boring Vaults across multiple EVM chains.
- Built Rust tooling with AI agents that automates the deployment and setup of Boring Vaults and proprietary smart contracts.
- Worked on Veda's Solana tooling.
- Created and reviewed admin transactions for a range of Boring Vaults.
- Code audited by Certora.

## Puffer Finance: Lead Engineer (Jun 2023 to Nov 2025)

- As lead engineer, architected and wrote pufETH (a customised ERC-4626 liquid restaking vault on EigenLayer) and its supporting contracts; the vault peaked at ~$1.8B TVL.
- Designed and ran the longest-running vampire attack on Lido: the vault accepted ETH and stETH, and stETH was systematically redeemed for ETH to spin up Puffer validators. Verifiable on-chain: pufETH still accepts stETH deposits and converts them to ETH.
- Shipped successive upgrades through upgradeable proxies (vault V1 to V5 on mainnet); deployed on L1 and L2.
- Ran audits end to end (scoping, price negotiation, fixes, final reports) with Nethermind, Trail of Bits, BlockSec, Cantina/Spearbit, Quantstamp, The Creed, SlowMist, Immunefi and Certora.
- Defined system invariants; fuzz and mainnet-fork testing; BlockSec Phalcon set to auto-pause the protocol on invariant breaks.
- Merkle-tree reward distribution, ERC-20s, subgraphs, deployment scripts, on-chain automation.
- Was a proposer and owner on multiple Safe multisigs, with strict operational security. Wrote runbooks and guides, and handled live frontend incidents.
- Oversaw all smart contract work; interviewed engineers; mentored juniors.

## Before web3: Backend Engineer (May 2016 to 2023)

Designed and built high-performance, scalable backend systems. TypeScript/JavaScript, Go, PHP, SQL/NoSQL, Redis, microservices, event-driven architecture, Docker, Docker Compose, CI/CD pipelines, Sentry, Datadog.

- Senior Backend Developer at Mukuru (https://www.mukuru.com), a Cape Town fintech founded in 2004 that moves money across borders for migrant workers and their families; it now serves 17M+ customers across Africa, Asia and Europe with remittances, payments and cards. This is where he stepped into fintech and started working on financial systems.

## Recommendations (LinkedIn)

Full texts are in resume.json under "references".

- Jason Vranek, CTO at Puffer Finance, managed him directly (Nov 2025): "He joined as one of Puffer's first Solidity developers and it's safe to say that it's due to his mastery of the language and expertise in best security practices that Puffer never had any security issues." Also credits him with going beyond the job description, "e.g., helping to drive the team's Rust development."
- William Tobin, Lead Smart Contract Engineer at Veda, managed him directly (Oct 2026): "Benjamin is a brilliant engineer with a deep understanding of the evm, smart contracts, and DeFi. He is an independent, adept problem solver, and he always produces results."
- Shayan Eskandari, senior colleague (Nov 2025): "Ben has a great security-aware mind for smart contract design and programming. He creates intertwined tools for forking mainnet, testing every detail of every change."
- Devin Glover, Smart Contract Engineer, senior colleague (Sep 2026): "always giving 100% while staying level-headed and improving existing systems rather than being content to leave them just functional."

## Security posture

Hardware wallets for all signing, signed Git commits enforced on GitHub, PGP key published on GitHub. Former proposer and owner on Puffer's production Safes; Puffer deployer key since wiped from his hardware wallet.

## AI and agents

- Early adopter of AI agents; uses them in day-to-day engineering and folds each new generation of tools and models into how he works.
- At Veda, built Rust tooling with AI agents that automates the deployment and setup of Boring Vaults (the vault plus its manager, teller and accountant contracts) and Veda's proprietary contracts across multiple EVM chains, so every launch runs the same way. Closed source, under NDA.
- Expert across different agents and models, and knows which fits which job (exploring a codebase, writing tests, reviewing a diff).
- Designs agentic workflows that chain agents and tools for multi-step engineering work, from planning and implementation to testing and review.
- Full stack with AI: ships frontend as well as smart contracts and backend, so can own a feature end to end.
- Agents speed up the work; he owns what ships. Agents never hold keys: signing goes through his hardware wallet.

## Skills

- Smart contracts: Solidity, ERC-4626, ERC-20, upgradeable proxies, OpenZeppelin, Merkle trees, Safe multisig and modules, EigenLayer
- Build and test: Foundry (forge, cast, anvil), Hardhat, invariant tests, fuzzing, mainnet-fork tests, Solana tooling
- Security and monitoring: Hypernative, Slither, Echidna, Certora, Tenderly, BlockSec Phalcon, Hexagate, Immunefi, PagerDuty, incident response
- Frontend and data: frontend (AI-assisted), viem, ethers.js, subgraphs, Etherscan and beacon chain explorers
- Languages and backend: high-performance, scalable systems; Rust (Alloy), TypeScript, Python, Go, JavaScript, PHP, SQL, NoSQL, Redis, Docker, Docker Compose, CI/CD, Sentry, Datadog

## Links

- [GitHub](https://github.com/bxmmm1)
- [Puffer contracts and audit reports](https://github.com/PufferFinance/puffer-contracts/tree/master/audits)
- [pufETH V1 (archived)](https://github.com/PufferFinance/pufETH)
- [Veda BoringVault](https://github.com/Veda-Labs/boring-vault)
- [Writing on dev.to](https://dev.to/bxmmm1)
- [Structured resume (JSON Resume)](https://bxmmm1.github.io/resume.json)