Hello, I'm
Rensley
Payments & On-Chain Infrastructure Engineer
// reasoning-first, backend-leaning — where fintech lies
New York City
Payments & on-chain infrastructure engineer — backend-leaning, security-minded.
I'm first a reasoning-and-logic developer. If the look isn't there, here are my words: judge me on the logic and the complexity of the project before you judge the way my button looks. I build fullstack, leaning backend — which is where fintech lies. Everything on this page is that argument, with receipts. — Rensley, on how to read this page
“I'm not a businessman, I'm a business, man.” — Jay-Z, Diamonds from Sierra Leone (Remix)
I'm a payments and on-chain infrastructure engineer — fullstack, but I live in the backend, where the money and the state actually move. I started at the Columbia FinTech Bootcamp on Python, forecasting, and algorithmic trading, and I've spent the years since going deep on payments, smart contracts, and security, based in New York City.
The center of that work is Access0x1 — an open-source, USD-priced payments rail, non-custodial, with its shared router live at one address across 9 public testnets, source-verified on 9 of them. I shipped it at ETHGlobal and took a prize from ENS. On top of it I built NFTeria — USD-priced checkout any merchant joins with one link.
At the core I'm a smart-contract engineer with an auditor's reflexes — I write them, then fuzz and hand-break them before anyone else can — and I build the systems that run on top, from ML trading to AI agents. Rust and Layer‑2 are where I'm headed next.
An on-chain credential — the EG-HACKER token held on Optimism
(contract
0x32382a82d9faDc55f971f33DaEeE5841cfbADbE0, wallet
0x53c61cfb8128ad59244e8c1d26109252ace23d14, balance
1).
// ETHGlobal Hacker Pack — onchain holder check (Optimism)
const { ethers } = require('ethers'); // npm install ethers
const provider = new ethers.JsonRpcProvider('https://mainnet.optimism.io');
const pack = '0x32382a82d9faDc55f971f33DaEeE5841cfbADbE0'; // ETHGlobal Hacker Pack (EG-HACKER)
const wallet = '0x53c61cfb8128ad59244e8c1d26109252ace23d14';
const abi = ['function balanceOf(address owner) view returns (uint256)'];
(async () => {
const held = await new ethers.Contract(pack, abi, provider).balanceOf(wallet);
console.log(`${wallet} ${held > 0n ? 'is' : 'is not'} a pack holder`); // → is (balance: 1)
})();Technologies and tools I work with daily.
Languages
Smart Contracts & Onchain
Backend & Databases
Cloud & DevOps
Architecture
AI & Machine Learning
Frontend
One open-source rail — Access0x1 — and the growing portfolio of live products built on it.
Access0x1
Onchain Payments — LiveOpen-source, on-chain payments + commerce + identity layer. One shared, multi-tenant Access0x1Router — zero custody, USD-priced via Chainlink feeds read inside the settlement transaction, exact fee-split — that any merchant joins with a single permissionless call and one link, no contract code required. On top sit ERC-6909 payment lanes, ERC-7702/6492 agent sessions, and a five-primitive commerce quintet. A universal deployer wires all 12 contracts in one command, and a standalone verifier re-uploads source to every explorer. The router lives at one deterministic address (0xe92244e3…) mirrored across 9 public testnets — Arc, Base, Ethereum, Optimism, Avalanche Fuji, Robinhood, Arbitrum, Celo Sepolia, and ZKsync Sepolia — source-verified on 9 of the 9, with 12 chains deployed in total. Testnet-only; no mainnet.
NFTeria
Onchain CommerceOnchain commerce product built on the Access0x1 rail. One link to accept USD-priced crypto checkout — non-custodial, settled on-chain with no server in the money path — so any merchant can sell onchain without writing contract code.
ClickReserv
Bookings SaaS — LiveA reservations and bookings platform for real-world service businesses — appointments, deposits, and payments, with an AI booking concierge and an installable PWA. Multi-tenant: every business gets its own branded storefront and payout wallet, on the same shared rail.
Colmado
Multi-tenant CommerceA storefronts-and-deliveries platform — many merchants, each running their own branded store, checkout, and fulfillment from one codebase on the shared rail.
SebasTN
Payments + Concierge OSA payments and concierge operating system for service businesses — Stripe checkout plus an embeddable AI assistant that drops onto any site with a single script tag.
A selection of what I've built — smart contracts, security, AI, trading systems, and full-stack.
GMX AI Trade System
DeFiAutonomous ML-powered trading bot for GMX perpetual DEX with self-training capabilities and real-time signal generation.
CRYVESTO 2.0
TradingAlgorithmic trading application with automated strategy execution and portfolio management.
BitBotApp
TradingTrading signals subscription service with real-time alerts and signal delivery.
DeFi Stablecoin
FoundryFoundry-based algorithmic stablecoin with collateralization mechanics and price oracle integration.
Cross-chain Rebase Token
CCIPCross-chain token with rebase mechanics using Chainlink CCIP for interoperability.
CRYVISOR
DeFiCrypto diversification application for portfolio analysis and optimization.
ETF Analyzer
FinanceFinancial database analysis with SQL for ETF performance tracking and visualization.
Access0x1 Router
VerifiedOpen-source, on-chain payments layer. One shared, multi-tenant router — zero custody, USD-priced via Chainlink feeds read in-tx, exact fee-split — that any merchant joins with one permissionless call. A universal deployer wires the contracts across every chain in one command. The router lives at one deterministic address (0xe92244e3…) mirrored across 9 public testnets, source-verified on 9 of the 9, with 12 chains deployed in total. 1,992 tests, 100% router coverage, 13 money-safety invariants.
NFTeria
Onchain — LiveOnchain commerce product built on Access0x1's open technology, live at nfteria.click. One link to accept USD-priced crypto payments, run an onchain storefront, and mint tamper-proof on-chain SVG credential NFTs — no code. Wallet-only auth via Sign-In-with-Ethereum with ENS and World ID trust tiers. Shipped as a static Next.js export pinned to IPFS and served via DNSLink — no server, no custody.
Foundry Fund Me
FoundryCrowdfunding smart contract with Chainlink price feeds and comprehensive Foundry test suite.
Smart Contract Lottery
FoundryVRF-based provably fair lottery with Chainlink VRF and Automation integration.
Foundry zkSync
L2Layer 2 development on zkSync with Foundry tooling for scalable smart contracts.
DAO Governance
FoundryOn-chain governance system with proposal creation, voting, and execution mechanics.
Account Abstraction
ERC-4337ERC-4337 account abstraction implementation for smart wallet functionality.
Upgradeable Contracts
FoundryProxy pattern implementations for upgradeable smart contracts.
Merkle Airdrop
FoundrySignature-based airdrop using Merkle tree proofs for efficient token distribution.
Coin Crowdsale
ERC-20Token crowdsale contract with minting capabilities and sale mechanics.
ElizaOS Agents
AIAutonomous AI agents built on ElizaOS framework for multi-purpose automation and interaction.
ChatHat
LLMLLM-powered chatbot with context-aware, retrieval-backed conversations.
CodeHat
LLMCode-generation LLM with intelligent, context-aware code assistance.
Flowise Chatbot
No-Code AIVisual LLM workflow chatbot built with Flowise for no-code AI pipeline creation.
Simli AI Avatar
AIElevenLabs AI agent with Simli-visualized avatar for interactive voice and visual AI experiences.
PDF LLM
RAGDocument processing with LLMs and RAG for intelligent PDF analysis and storage.
LLM Agents
AgentsCustom LLM agent framework with tool use and autonomous task completion.
Hush-Brush
AppBeauty industry application for salon management and client booking.
BarberShopPlay
AppBarber shop management application with scheduling and client management.
BeautyPOS
POSPoint of sale system designed for beauty and grooming businesses.
CrowdScope
AppCrowd analytics application for event management and audience insights.
CodeHawks: Token-0x
AuditCompetitive smart contract security audit on the CodeHawks platform.
Puppy Raffle Audit
AuditSecurity audit identifying reentrancy vulnerabilities, weak randomness, and integer overflow issues.
Santa's List Audit
AuditSmart contract vulnerability assessment and security review.
Multisig Timelock Audit
AuditMulti-signature wallet and timelock security review for governance contracts.
Audit Report Template
ToolingStandardized audit reporting framework for consistent and professional security assessments.
Deep Learning Neural Network
MLVenture funding predictions with deep learning using TensorFlow neural networks.
Credit Risk Classification
MLCredit risk analysis using resampling techniques and classification models.
Forecasting Net Prophet
MLTime series forecasting with Prophet for financial market predictions.
Financial Simulations
FinanceMonte Carlo simulations and API-driven financial modeling.
PyViz Data Visualization
DataInteractive data visualization dashboards with PyViz ecosystem.
Unsupervised ML Clustering
MLClustering analysis with unsupervised machine learning algorithms.
Robo-Advisor
FinanceAutomated investment advisor with portfolio optimization and risk assessment.
Algo Forecaster App
MLForecasting bot rentals and subscription service with ML-powered predictions.
CodeHawks competitive auditor — 1,144 EXP • 17 Findings
“If I can't do it, homie, it can't be done.” — 50 Cent, If I Can't
Token0x: NFTeria
Security audit of NFTeria's onchain commerce, which builds on the Access0x1 router. Reviewed the money path — USD pricing read in-tx, exact fee-split, no-custody settlement, and the ERC-6909 payment-lane firewall — backed by 13 money-safety invariants holding under the fuzzer with zero reverts.
Verify Everywhere
Source-verification assurance for the Access0x1 stack. A standalone, idempotent verifier re-uploads contract source to every target explorer — Etherscan, Blockscout, Routescan, and Sourcify — so deployed bytecode is publicly auditable on Base Sepolia, Ethereum + Optimism Sepolia, and Avalanche Fuji (Arc Testnet + Robinhood Chain pending) with no keystore in the loop.
Puppy Raffle
Identified reentrancy vulnerabilities, weak randomness in winner selection, and integer overflow risks in fee calculations.
Santa's List
Smart contract vulnerability assessment covering access control, state manipulation, and logic flaws in the naughty/nice list system.
Multisig Timelock
Security review of multi-signature wallet and timelock governance contracts. Assessed signing threshold logic and timelock bypass risks.
Security Toolkit
Where it started.
Cyfrin Updraft
Advanced smart contract security and DeFi development. Foundry fundamentals, smart contract auditing, security research, DeFi stablecoins, account abstraction, DAO governance, upgradeable contracts, and assembly/formal verification. Massive props to Patrick Collins for building Cyfrin Updraft — the best smart contract education in the space.
Columbia FinTech Executive Bootcamp
Six-month intensive program focused on blockchain technologies and financial applications. Gained hands-on experience with Python programming, portfolio app development, forecasting models (TensorFlow, Scikit-Learn), algorithmic trading, AWS Lambda, smart contract development, and dApp architecture.