
Dan Field
Verified Expert in Engineering
Full-stack Developer
Corby, United Kingdom
Toptal member since October 18, 2022
Dan is a software architect, CTO, and principal engineer with nearly 30 years of experience delivering AI, blockchain, and fintech solutions for startups and enterprises. He specializes in agentic AI systems, LLM-powered applications, distributed systems, cloud infrastructure, and high-performance backend services. Dan is known for rapidly turning complex business requirements into scalable, production-ready platforms.
Portfolio
Experience
- Node.js - 12 years
- Blockchain - 7 years
- TypeScript - 6 years
- Ethereum - 5 years
- Smart Contracts - 5 years
- Solidity - 5 years
- Web3.js - 5 years
- Ethers.js - 4 years
Preferred Environment
Solidity, TypeScript, Node.js, React, SQL, Amazon Web Services (AWS), Rust, PostgreSQL, Claude, ChatGPT
The most amazing...
...The most amazing projects I’ve developed include multiple world-first products, from pioneering blockchain platforms to a unique video optimization technology.
Work Experience
AI, Blockchain & Fintech Software Architect
Freelance Clients
- Designed and built AI-powered applications, agentic systems, LLM-based tools, workflow automation, and production backend services for startup and commercial clients.
- Architected complex blockchain and fintech platforms across Ethereum, Solana, DeFi, trading automation, analytics, wallets, APIs, and cloud infrastructure.
- Delivered senior technical leadership across architecture, implementation, security, performance optimization, deployment, and client-facing technical strategy.
- Helped clients move from ambiguous requirements to working production systems by combining hands-on engineering with CTO-level product and architecture guidance.
Full-stack Developer
Freelance Clients
- Delivered senior software architecture and full-stack development for clients across AI, blockchain, fintech, DeFi, eCommerce, and SaaS.
- Built agentic AI systems, LLM-powered tools, Web3 applications, smart-contract integrations, trading systems, analytics dashboards, backend APIs, and cloud-based platforms.
- Led projects from requirements and architecture through implementation, testing, deployment, security review, and production support.
- Combined CTO-level technical judgment with hands-on delivery across TypeScript, Node.js, React, Python, Solidity, Rust, SQL, AWS, Docker, and modern AI tooling.
Chief Technology Officer (CTO)
Millenoki
- Designed and developed a new IoT security and management platform to meet market gaps, including hands-on development and management of all software and hardware work.
- Built and designed several API endpoints for a secure IoT solution utilizing TypeScript, Nest.js, PostgreSQL, MySQL, and AWS.
- Invented a unique mobile video compression service, a novel service able to compress video streams, including management of all developers and overseas development teams.
- Conceived and launched a unique mobile data compression tech and apps for iOS and Android.
- Managed all technical innovations and inventions at Millenoki, enabling the company to grow and develop new intellectual property.
- Created the development office, including hiring, management, and mentoring of all technical employees.
- Devised and developed data-saving apps for iOS and Android.
- Implemented real-time reporting services for mobile devices integrated with a big data platform based on Apache Cassandra, Redis, and RabbitMQ.
- Developed a real-time big data analytics platform utilizing Java, Node.js, Reddit, RabbitMQ, and Apache Cassandra.
DeFi Analytics Engineer
Acre.fi
- Built Dune Analytics dashboards to track protocol activity, user behaviour, TVL, deposits, withdrawals, wallet activity, and key on-chain flows.
- Translated complex blockchain data into clear business metrics for product, growth, investor reporting, and operational decision-making.
- Developed reusable SQL queries and dashboard components to support ongoing protocol analysis and stakeholder reporting.
Software Architect / Rescue Engineer
Pure Intentions Coffee
- Took over an abandoned inventory-management platform, reviewed and secured the application and cloud environment, removed previous developer access, and stabilized the system for continued production use.
- Added secure production operations including scripted deployments, rollback procedures, database backups, restore workflows, health checks, and documented disaster-recovery runbooks.
- Reworked core inventory logic, including usage-rate calculations, reorder levels, stock-reduction fixes, and historical inventory snapshots.
- Delivered business-critical features including inventory exports, item statuses, notes, seasonal workflows, inline status updates, goods-receipt notifications, and urgency-email tracking.
- Improved production reliability and maintainability through stronger test coverage, better API error handling, deterministic stock calculations, safer database operations, and environment configuration hygiene.
Solana Trading Automation Architect
Private Client
- Architected and built a production-focused Solana trading automation platform covering signal ingestion, trade decisioning, execution, exit management, monitoring, reporting, and deployment.
- Delivered advanced trading workflows designed to improve entry quality, manage downside risk, capture upside, and support fast-moving market opportunities.
- Integrated the platform with the Solana trading ecosystem, enabling automated discovery, evaluation, and execution of trading opportunities across multiple liquidity sources.
- Built operational visibility into trading performance, system behaviour, data quality, and daily reporting so decisions could be reviewed and improved over time.
- Hardened the platform for live operation with secure access controls, production deployment processes, governed trading parameters, reliability improvements, and long-running stability fixes.
Solana Developer with Strong Experience with Telegram Bots and Speed of Trade Execution
LANCELOT GROUP LIMITED
- Architected and built a production-focused Solana trading automation platform covering signal ingestion, trade decisioning, execution, exit management, monitoring, reporting, and deployment.
- Delivered advanced trading workflows designed to improve entry quality, manage downside risk, capture upside, and support fast-moving market opportunities.
- Integrated the platform with the Solana trading ecosystem, enabling automated discovery, evaluation, and execution of trading opportunities across multiple liquidity sources.
- Built operational visibility into trading performance, system behaviour, data quality, and daily reporting so decisions could be reviewed and improved over time.
- Hardened the platform for live operation with secure access controls, production deployment processes, governed trading parameters, reliability improvements, and long-running stability fixes.
Web-based Inventory Management System Developer
Pure Intentions Roasting Co., LLC DBA Pure Intentions Coffee
- Rescued and stabilized an abandoned inventory-management platform, securing the application and cloud environment, removing previous developer access, and restoring client confidence in the system.
- Added secure production operations including scripted deployments, rollback procedures, PostgreSQL backups, WAL archiving, restore workflows, health checks, and documented disaster-recovery runbooks.
- Reworked core inventory logic, including usage-rate calculations, reorder levels, calendar-month aggregation, partial-month estimates, stock-reduction fixes, and historical inventory snapshots.
- Delivered business-critical features across Rails and React, including inventory exports, item statuses, notes, seasonal workflows, inline status updates, goods-receipt notifications, and urgency-email tracking.
- Improved production reliability and maintainability through stronger test coverage, better API error handling, deterministic stock calculations, safer database operations, and environment configuration hygiene.
Solana Developer
Lancelot Group Limited
- Built and optimized low-latency crypto trading systems, improving execution speed, reliability, and overall bot performance in live market conditionS.
- Integrated blockchain data, routing, and execution logic to automate trade decisions from real-time signals and market events.
- Designed resilient 24/7 trading infrastructure with monitoring, restart mechanisms, and alerting to reduce downtime and missed opportunities.
- Worked extensively with Solana and EVM market data, transaction flows, and liquidity sources to support real-time pricing, execution, and validation.
- Built bot infrastructure that ingested external signals, enriched them with on-chain data, and executed trades according to configurable strategy rules.
- Improved execution pipelines by identifying latency bottlenecks, optimizing critical paths, and reducing failure points during volatile market conditions.
- Integrated APIs, RPC services, and exchange or DEX connectivity layers to support reliable automated execution across blockchain environments.
Web-based Inventory Management System Developer
Pure Intentions Roasting Co., LLC (dba Pure Intentions Coffee)
- Diagnosed and resolved production issues across legacy and modern web applications, restoring stability and reducing repeated support overhead.
- Managed Linux-based cloud infrastructure, including Hetzner-hosted environments, to troubleshoot deployments, access codebases, and restore broken services.
- Reviewed existing architectures, identified root causes across application, API, and database layers, and implemented targeted fixes to improve reliability.
- Worked extensively with MySQL-backed systems, tracing data and query issues to correct business logic errors and improve application accuracy.
- Integrated and debugged REST APIs and external service connections, ensuring consistent data flow between back-end systems and user-facing applications.
- Improved maintainability of inherited codebases by documenting findings, clarifying system behavior, and delivering practical fixes for future support.
- Built and supported inventory- and operations-focused business systems, aligning application behavior with real-world stock, allocation, and workflow rules.
- Tested fixes end-to-end in live-like environments to confirm stability, prevent regressions, and verify that user-facing workflows worked correctly.
- Balanced back-end problem-solving with front-end awareness, making changes that improved both system correctness and day-to-day usability.
Dune Analytics Specialist for a DeFi Data Dashboard Project
Acre Stakes Inc.
- Delivered on-chain analytics for Acre.fi using Dune, creating dashboard reports that surfaced protocol usage, asset flows, wallet behaviour, and key growth metrics.
- Helped the team turn raw blockchain data into actionable insight for product, marketing, investor updates, and ecosystem reporting.
- Improved visibility into how users interacted with the protocol by designing clear metrics, structured queries, and easy-to-read dashboard views.
GCP and Ethereum Data Engineer
Verus.ai Ltd
- Developed efficient Ethereum ETL routines, enabling the processing of all blockchain data from block 0 to current blocks for an investor company.
- Architectured a time-series and relational database model to efficiently hold all blockchain data for multiple chains, allowing for artificial intelligence and machine learning algorithm access to the large dataset.
- Offered consultancy and advice on various big data access and analytic issues.
- Developed a high-speed data ingestion pipeline in TypeScript, utilizing ORM for models and Postgres for data outputs. Transformed a massive amount (TBs) of CSV files into a fast analytical database.
- Developed metadata enrichment processes in TypeScript utilizing various APIs to enrich original Ethereum data.
Founder | Chief Technology Officer (CTO)
ClearMyMail
- Designed, developed, and launched ClearMyMail, the world's only guaranteed anti-spam service.
- Developed custom simple mail transfer protocol (SMTP), post office protocol (POP3), and internet message access protocol (IMAP) services which included 100% anti-spam protection.
- Raised investment and grew to get paying customers in over 30 countries within the first two years.
Experience
Early ERC-721 Blockchain Game
The project allowed users to collect NFTs, interact directly with blockchain state, and participate in on-chain game mechanics. It demonstrated early practical experience with NFTs, tokenized assets, smart contracts, wallet integrations, and consumer-facing blockchain products.
ERC-20 Algorithmic Token
Polygon MATIC Yield Farm and DEX
Crypto Gaming Dapp for TRON
Solana Trading Automation Platform
The project involved designing reliable trading workflows, integrating with the Solana ecosystem, improving operational visibility, and hardening the platform for live use. It combined blockchain infrastructure, trading automation, backend engineering, security, analytics, and production operations.
AI and Agentic Workflow Systems
The work included building practical AI services that help businesses automate complex tasks, improve decision-making, process information more efficiently, and integrate AI capabilities into existing products and operations.
InventoryOS Production Rescue and Inventory Platform
Delivered new inventory features, reporting workflows, stock calculations, historical snapshots, notifications, deployment automation, secure backups, restore procedures, and operational runbooks. The project combined rescue engineering, Rails/React development, cloud infrastructure, security, and production reliability.
DeFi Protocol Analytics Dashboards
The dashboards translated complex blockchain data into practical business metrics for product decisions, growth analysis, investor reporting, and protocol operations. The project combined DeFi knowledge, SQL, blockchain analytics, and stakeholder-focused reporting.
Skills
Libraries/APIs
Node.js, React, Web3.js, REST APIs, Crypto++, FFmpeg, OpenZeppelin, Vue, Google Maps, Stripe, Binance API, Solana.py, jQuery, Google Cloud API, Devise, Recharts, Claude API
Tools
JavaScript Toolchain, Remix IDE, BigQuery, VPN, TestFlight, Xcode, GitHub, Microsoft Excel, Git, RabbitMQ, Geth (go-ethereum), n8n, Claude, ChatGPT, Docker Compose, Docker Swarm, Claude Code, NGINX, Chatbox, Codex, Claude Agent SDK
Languages
Solidity, TypeScript, Java, SQL, Rust, Python, JavaScript, PHP, HTML5, CSS, HTML, Go, C++, GraphQL
Frameworks
Hardhat, NestJS, Express.js, Vanilla JS, Symfony, Agentic Frameworks, React Native, Next.js, Truffle, Parity Polkadot, Ruby on Rails (RoR), JSON Web Tokens (JWT), Tailwind CSS
Paradigms
Microservices, ETL, Concurrent Programming, Event-driven Architecture, Role-based Access Control (RBAC)
Platforms
Blockchain, Ethereum, Decentralized Exchanges (DEXs), Blockchain Platforms, Amazon Web Services (AWS), Apple, iOS, Docker, Android, Linux, WordPress, Vercel, Azure, Apache Kafka, AWS Lambda, Visual Studio Code (VS Code), Google Cloud Platform (GCP)
Storage
PostgreSQL, Databases, Redis, MySQL, JSON, Database Administration (DBA), API Databases, Data Pipelines, Cassandra, MongoDB, MSSQLCE, Google Cloud, SQLite, PostGIS
Industry Expertise
High-frequency Trading (HFT)
Other
Ethers.js, Big Data, Cloud, APIs, Non-fungible Tokens (NFT), Decentralized Finance (DeFi), Utility Tokens, ERC-20, ERC-721, ERC-1155, Smart Contracts, Polygon, Infura, OpenEthereum, Bots, Software Architecture, Cryptocurrency, Digital Payments, Ethereum Smart Contracts, Cryptocurrency Wallets, Payment APIs, P2P, Project Consultancy, Advisory, Networks, Tokenomics, Full-stack, Blockchain Design, Architecture, Back-end, Solana, RPC, Payment Solutions, Payment Systems, Ethereum Virtual Machine (EVM), Artificial Intelligence (AI), Minimum Viable Product (MVP), Startups, Blockchain & Cryptocurrency, Full-stack Development, Web Development, AI Agents, Large Language Models (LLMs), Fintech, API Integration, CTO, Financial APIs, Bitcoin, Web3, OpenAI, Retrieval-augmented Generation (RAG), Indexing, Token-2022, WebSockets, Security, User Authentication, Code Review, OAuth, Foundry, Permit2, Data Architecture, Fractional CTO, Amazon Webstore, Data Analysis, Data Reporting, Web UX, Web App UX, Inventory Management, Proxies, Proxy Servers, Telegram Bots, Product Delivery, Blockchain Development, Encryption, eCommerce APIs, Technical Leadership, API Design, Integration, Dashboards, Data Modeling, SaaS, Workflow Automation, Payments, Data Engineering, Agentic AI, Mobile App Development, Cloud Infrastructure, Software Development, System Architecture, Mobile Apps, Tron Blockchain, iOS TV, Trading, Audits, Discord Bots, Chatbots, LoRa, Front-end, WhatsApp, AI Chatbots, Algorithmic Trading, Board Reporting, Machine Learning, User Interface (UI), Email, POP3, IMAP, SMTP, Stablecoins, Timescale, Deployment, Platform Engineering, FastAPI, Tailwind UI, Axios, Optimization, Requirements & Specifications, Analytics, dune, Dune Analytics, Gemini, Gemini API, Trading Bots, GRAPH, Dune Anlytics, Embedded Rust, Artificial Intelligence of Things (AIoT)
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