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Senior Software Engineer · onchain finance

Remote · CET/CEST

Benjamin Halimic

ex-Puffer · contracts → tooling → UI

Portrait of Benjamin Halimic

Lead Engineer at Puffer Finance, then Senior Software Engineer at Veda

I build and secure onchain financial systems, from the smart contracts to the tooling that deploys and runs them. As lead engineer at Puffer Finance, I architected and wrote the pufETH vault and its supporting contracts: $1.8B peak TVL, five mainnet versions, zero exploits. At Veda, I built Rust tooling with AI agents that automates the deployment and setup of Boring Vaults and proprietary smart contracts.

Message on Telegram Email GitHub LinkedIn

benjaminxh@gmail.comt.me/bxmmmmgithub.com/bxmmm1linkedin.com/in/benjamin-halimicbxmmm1.github.io

On-chain proof: Puffer deployer 0xb7d8…5d76, ownership signature verified on Etherscan; the key has since been wiped.

Full stack, contracts to frontend · Remote · Central European Time (UTC+1/+2) · shipping production code since 2016

/// @notice invariants

Numbers that held on mainnet

pufETH.totalAssets()

$1.8B

Peak TVL of the pufETH vault I architected and wrote.

assert(exploits == 0)

0

Smart contract hacks or incidents, across every upgrade.

vault.version()

V5

Upgrades shipped to the same live vault on Ethereum mainnet.

auditors.length

9

Audit firms and security platforms I've worked with directly.

/// @notice experience

Where I've shipped

–

Veda Senior Software Engineer

Veda provides the vault infrastructure behind enterprise Earn products. Its BoringVault standard has handled $32B+ in volume for 320K+ users across EVM chains and Solana, is audited by Spearbit, Macro, Secure3 and Hexens, and carries a $1M Immunefi bug bounty.

powers → Kraken DeFi Earn MetaMask Money Account EtherFi Liquid Lido Earn Plasma One

  • Deployed Boring Vaults across multiple EVM chains. BoringVault is Veda's Merkle-verified vault architecture: a minimal vault, with strategies, deposits and pricing handled by separate manager, teller and accountant contracts.
  • 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.

Most of my Veda work was in closed-source repositories and is covered by an NDA. I'm happy to talk about it at a high level, but I can't share code or confidential details.

Veda-Labs/boring-vault ↗ Veda docs ↗

–

Puffer Finance Lead Engineer

A liquid restaking protocol on EigenLayer that lets anyone run an Ethereum validator with far less than 32 ETH. The pufETH vault crossed $1B in deposits within three weeks of launch, and Puffer raised an $18M Series A led by Brevan Howard Digital and Electric Capital.

Built

  • As lead engineer, architected and wrote pufETH, Puffer's liquid restaking token on EigenLayer, and its supporting contracts. The vault, a customised ERC-4626, peaked at ~$1.8B TVL.
  • Designed and ran the longest-running vampire attack on Lido. The vault accepted ETH and stETH, and we systematically redeemed the stETH for ETH to spin up Puffer validators. You can verify it on-chain: pufETH still accepts stETH deposits and converts them to ETH.
  • Shipped successive upgrades through upgradeable proxies, taking the live vault from V1 to V5 on mainnet, and deployed contracts on L1 and L2.
  • Built Merkle-tree reward distribution, ERC-20s and extended OpenZeppelin contracts. Wrote the deployment scripts, automated on-chain transactions and shipped subgraphs so the frontend and backend could read on-chain data.

Secured

  • Ran audits end to end: scoping, price negotiation, fixing findings, and shaping final reports for public and investor audiences.
  • Defined system invariants and covered them with fuzz and mainnet-fork tests. Set up BlockSec's Phalcon to pause the protocol automatically if an invariant breaks on-chain.
  • Was a proposer and owner on multiple Safe multisigs, with strict operational security. Triaged findings from an Immunefi audit competition, wrote runbooks and guides, and handled live frontend incidents.

Led

  • Oversaw all smart contract work. Walked the frontend and backend teams through technical flows, and turned business-development requirements into contract designs.
  • Interviewed backend and smart contract engineers, mentored junior developers and ran knowledge-sharing sessions.

puffer-contracts ↗ pufETH V1, archived ↗ audit reports ↗ Puffer Institutional ↗

–

Before web3 Backend Engineer

Seven years building high-performance, scalable web2 systems before moving to smart contracts full time.

Mukuru · Senior Backend Developer

  • Mukuru is 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 I stepped into fintech and started working on financial systems.

Across these roles

  • Designed and built high-performance, scalable backend systems in TypeScript/JavaScript, Go and PHP, backed by SQL, NoSQL and Redis.
  • Monoliths and microservices, with event-driven architecture, containerised with Docker and Docker Compose and shipped through CI/CD pipelines.
  • Production monitoring and analytics with Sentry and Datadog.

/// @custom:cosigners

Co-signed by the people I've shipped with

Recommendations from my managers and colleagues at Puffer and Veda, published on my LinkedIn profile.

● managed me directly

“Ben is a rockstar. 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. … Ben is quick to identify what's needed to get the job done. This meant going above and beyond the job description which is so important in a fast-paced startup, e.g., helping to drive the team's Rust development. … 10/10 would recommend Ben to anyone lucky enough to work with him.”
Jason Vranek, CTO at Puffer Finance

● managed me directly

“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.”
William Tobin, Lead Smart Contract Engineer at Veda

● senior colleague

“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, and understand[s] the underlying technology of the EVM/Ethereum. I enjoyed working with him—and his cat. 5 stars :)”
Shayan Eskandari, Postdoc at Nova SBE

● senior colleague

“Ben has a great mind for engineering and is a pleasure to work with! Throughout my time working with him, he was always giving 100% while staying level-headed and improving existing systems rather than being content to leave them just functional. I hope to work with him again and know he would make a fine addition to any dev team!”
Devin Glover, Smart Contract Engineer

All recommendations on LinkedIn ↗

/// @custom:security audits

Security from the protocol side of the table

I've taken code through reviews with nine audit firms and security platforms, from scoping and pricing to fixing findings and getting reports ready for public release. Puffer's contracts repository alone publishes 23 audit reports.

● attestationNethermind Security

“The Puffer team exemplifies professionalism in every aspect. Their commitment to excellence is evident in their meticulous maintenance of a high-quality codebase complemented by comprehensive documentation. In our experience, their responsiveness to inquiries during audits has been exceptional.”
Cristiano Silva, Web3 Security Manager, Nethermind Security, on auditing Puffer

Personal opsec

Security starts with my own setup

The same rules I'd expect from anyone who signs admin transactions for live vaults.

hardware_wallets
requiredAll signing goes through hardware wallets
commit_signing
enforcedSigned Git commits on GitHub
multisig_signer
formerProposer and owner on Puffer's production Safes
deployer_key
wipedPuffer deployer key removed from my hardware wallet
pgp_key
publishedPublic key on my GitHub profile

/// @dev agents

AI-native engineering

I picked up AI agents early and never put them down. Working across different agents, and designing the workflows that connect them, is now a core part of how I build: contracts, tests, tooling and frontend. What doesn't change is who is responsible. Agents speed up the work, I own what ships, and they never hold keys: signing still goes through my hardware wallet.

  • adopter.since(early)

    Early adopter

    Using AI agents in day-to-day engineering since the early days, and folding each new generation of tools and models into the way I work.

  • agents.length > 1

    Fluent across agents

    Expert with a range of agents and models, and I know which one fits which job, from exploring an unfamiliar codebase to writing tests or reviewing a diff.

  • workflow.run(agents, tools)

    Agentic workflows

    I design agentic workflows that chain agents and tools together to take on multi-step engineering work, from planning and implementation to testing and review.

  • developer.stack = "full"

    Full stack with AI

    With AI agents in my workflow I ship frontend too, so I can take a feature end to end, from smart contracts to backend and UI, without waiting on a handoff.

Case study · Veda

Deployment tooling in Rust, built with AI agents

Launching a Boring Vault means deploying the vault with its manager, teller and accountant contracts, then setting all of them up, on every chain it goes to. I built Rust tooling, with AI agents, that automates the deployment and setup of Boring Vaults and Veda's proprietary contracts, so every launch runs the same way.

language
rustDeployment and setup tooling
built_with
ai_agentsAgents in the loop while building it
deploys
boring_vaultsVault, manager, teller and accountant, plus Veda's proprietary contracts
chains
multi_evmBoring Vaults deployed across multiple EVM chains
admin_txs
reviewedAdmin transactions created and reviewed for a range of vaults
source
closedUnder NDA, happy to walk through it at a high level

/// @dev toolchain

What I work with

Smart contracts

  • Solidity
  • ERC-4626
  • ERC-20
  • Upgradeable proxies
  • OpenZeppelin
  • Merkle trees
  • Safe multisig & modules
  • EigenLayer

Build & test

  • Foundry
  • Cast
  • Anvil
  • Hardhat
  • Invariant tests
  • Fuzzing
  • Mainnet-fork tests
  • Deployment scripts
  • Solana tooling

Security & monitoring

  • Slither
  • Echidna
  • Certora
  • Tenderly
  • Hypernative
  • BlockSec Phalcon
  • Hexagate
  • Immunefi
  • PagerDuty
  • Incident response

Frontend & data

  • Frontend, AI-assisted
  • viem
  • ethers.js
  • Subgraphs
  • Etherscan
  • Beacon chain explorers
  • On-chain automation

Languages & backend

  • Rust
  • Alloy
  • TypeScript
  • Python
  • Go
  • JavaScript
  • PHP
  • SQL
  • NoSQL
  • Redis
  • Microservices
  • Event-driven
  • Docker
  • Docker Compose
  • CI/CD
  • Sentry
  • Datadog

AI & agents

  • AI agents
  • Agentic workflows
  • Multi-agent setups

/// @custom:security-contact

Open to senior engineering roles

I'm looking for senior engineering roles across the stack: smart contracts and protocols, backend, frontend, or all of them at once. I'm also open to focused freelance work. I've been shipping production code since 2016 and can own a feature end to end. Telegram is the fastest way to reach me.

Telegram @bxmmmm Email LinkedIn Writing on dev.to
email
benjaminxh@gmail.com
telegram
@bxmmmm
timezone
CET/CEST (UTC+1/+2), with overlap for US and Asia calls
references
4 recommendations on LinkedIn, and teammates from Puffer and Veda on request