William Wolff, Full-stack Developer in Berlin, Germany
William Wolff

Full-stack Developer in Berlin, Germany

Member since September 22, 2022
William has over eight years of experience as a senior software engineer, architect, and consultant. He builds full-stack applications from scratch and solutions that integrate with existing services and infrastructure. For the past three years, William has been deeply involved in building cutting-edge blockchain solutions ranging from NFT platforms over transaction batching to dApp development. He has worked with startups and leading players in the industry like Input Output and more.
William is now available for hire

Portfolio

  • Berlin Pool
    Docker, Ansible, Terraform, Cardano Blockchain, Node.js, Ubuntu, TypeScript...
  • IOHK
    Cardano Blockchain, UTXO, EUTxO, Non-fungible Tokens (NFT), Native Assets...
  • MDL Mobility Data Lab
    Java, Vert.x, Ansible, Terraform, Python, Bash Script, Ubuntu, Docker...

Experience

Location

Berlin, Germany

Availability

Full-time

Preferred Environment

Ubuntu, JVM, Vert.x, TypeScript, Cardano Blockchain, UTXO, React, Docker, Blockchain, ELK (Elastic Stack)

The most amazing...

...I've built is a lossless staking lottery dApp using Cardano's smart contract language Plutus. Players play for each player's principle's yield.

Employment

  • Stake Pool Operator | IT Infrastructure Specialist

    2021 - PRESENT
    Berlin Pool
    • Ran and maintained stake pool for PoS blockchain Cardano with multiple, geographically distributed, fail-safe, redundant server setups.
    • Used Terraform for provisioning and Ansible for configuring servers and private networks, security, and hardening while adhering to the IaC principles.
    • Followed best practices for secure, automated server provisioning, which included air-gapped environments and key and certificate management.
    • Gained experience in Docker container management and Docker Compose for custom images.
    Technologies: Docker, Ansible, Terraform, Cardano Blockchain, Node.js, Ubuntu, TypeScript, Java, UTXO, Non-fungible Tokens (NFT), Cloud Storage, PostgREST, PostgreSQL, JUnit, Software Development, Bash Script, EUTxO, Blockchain, APIs, gRPC, Integration, Cryptocurrency, Blockchain & Cryptocurrency, GraphQL, CSS, Decentralized Systems, REST, Decentralization
  • Senior Solutions Architect

    2021 - 2022
    IOHK
    • Created a solution design for the NFT platform to support lending and borrowing for real estate, raising investments from crypto markets.
    • Supported design for decentralized identity (DID) and verified credential (VC) solution, Atala PRISM.
    • Presented Cardano's extended unspent transaction output (eUTXO) model to the AWS team for integration.
    • Supported the pioneering of verified NFTs for preventing possible copies of existing non-fungible tokens for major brands.
    Technologies: Cardano Blockchain, UTXO, EUTxO, Non-fungible Tokens (NFT), Native Assets, Blockchain, Plutus, Ubuntu, TypeScript, Java, Haskell, Cloud Storage, PostgREST, PostgreSQL, JUnit, Apache Maven, Software Development, Software Architecture, JVM, Bash Script, Node.js, Elasticsearch, Spring, Spring Boot, REST APIs, APIs, gRPC, Integration, API Integration, Smart Contracts, JSON-RPC, Ethereum, Responsive Layout, Decentralized Finance (DeFi), Cryptocurrency, Trading, Blockchain & Cryptocurrency, GraphQL, CSS, Decentralized Systems, Blockchain Platforms, Decentralization
  • Lead Engineer and CTO

    2020 - 2021
    MDL Mobility Data Lab
    • Developed a JVM back-end service for IoT devices, such as screens and displays mounted on top of cars used for car sharing.
    • Built the React front end that displayed real-time advertising streamed from the back end.
    • Maintained configuration and deployment of IoT devices via Docker, Ansible, and Terraform.
    Technologies: Java, Vert.x, Ansible, Terraform, Python, Bash Script, Ubuntu, Docker, ELK (Elastic Stack), Logstash, Elasticsearch, React, Cloud Storage, PostgREST, PostgreSQL, JUnit, Software Development, Software Architecture, JVM, Spring, Spring Boot, REST APIs, APIs, Integration, API Integration, JSON-RPC, HTML, CSS
  • Senior Software Engineer and Software Architect

    2016 - 2019
    Deloitte
    • Led a team of 12 engineers. Oversaw and planned development cycles, roadmap, and tasks via Jira.
    • Developed and architected automated migration and runtime for interpreted language to Java 8 for a major insurance company.
    • Created a 3-step migration process for the software stack and conducted E2E testing in a native environment.
    Technologies: Lombok, JVM, Ubuntu, Cloud Storage, JUnit, Apache Maven, Software Development, Software Architecture, REST APIs, APIs, gRPC, Integration, API Integration, CSS
  • CTO | Co-Founder

    2015 - 2017
    CityXcape
    • Developed an iOS mobile app, web app, and back end for a social network app allowing players to join virtual scavenger hunts to explore cities and collect digital items (stamps) by verifying locations posted by others.
    • Built different back-end versions with Ruby on Rails and later used Django.
    • Developed architecture, backup system, and integrated Uber's H3 geospatial hexagon-based grid for mobile for a different map experience.
    • Managed up to four engineers while also supporting development.
    • Created design artifacts for visual content within the app and a web front end. Everything from icons to logos and group emblems for different city tribes.
    Technologies: TypeScript, Python, Django, Swift, Xcode, Firebase, Firebase Web SDK, Firebase iOS SDK, Firebase Analytics, Firebase Hosting, Cloud Firestore, Firebase Realtime Database, Firebase Cloud Functions, Google Cloud Functions, Firebase Cloud Messaging (FCM), Firebase Authentication, Node.js, JavaScript, Ruby on Rails 5, Uber H3, GIS, Geospatial Analytics, Amazon Web Services (AWS), Amazon EC2, Amazon DynamoDB, AWS Lambda, Amazon S3 (AWS S3), Mapbox, Mapbox SDK, Mapbox iOS SDK, iOS, Software Development, Software Architecture, Business to Business (B2B), Entrepreneurship, REST APIs, APIs, Integration, HTML, Responsive Layout, Responsive Web Design (RWD), Responsive UI, CSS

Experience

  • JVM Vert.x-based PoW blockchain
    https://github.com/will991/vertx-pow-blockchain

    A Vert.x-based proof of work (PoW) blockchain illustrating use cases of the framework. It allows for peer discovery via clustering and offers a REST API for retrieving all information, such as the current UTXO set or mining endpoints.

  • Cardano Blockchain REST API
    https://github.com/adagate-io/adagate-api

    Another Vert.x-based back-end service that can be deployed as a chain indexer with a Cardano node and Cardano DB Sync instance and as software as a service (SaaS). It fetches all information from the blockchain and offers WebSocket support for real-time data streams, such as blocks and transactions.

  • CityXcape
    https://github.com/will991/CityXcape-iOS

    A Swift-based mobile application for communities that allows sharing (secret) spots within urban places and cities that others have to find in a game-like manner. It uses Uber's H3 hexagon-based geospatial library, introduces a native token as an incentive to do certain in-game actions, and stores achievements such as verifying spots from others. The app has been available on the App Store for more than 1.5 years and has around 5,000 users.

  • UTXO NFT Maker

    I created the official tool for IOHK's professional service group (PSG). It is a Docker image and container for reusability and simplification of creating NFTs on Cardano—true NFTs via UTXO consumption. Without much Plutus and Haskell knowledge, one case runs a container, provides specific inputs to pay the transaction fee, adds NFT metadata, and automatically mints and submits the transaction to the blockchain.

Skills

  • Languages

    Java, HTML, CSS, Swift, JavaScript, TypeScript, Python, Bash Script, Haskell, GraphQL
  • Frameworks

    Vert.x, JUnit, Spring, Django, Ruby on Rails 5, Spring Boot, gRPC
  • Paradigms

    REST, Responsive Layout, Responsive Web Design (RWD)
  • Platforms

    Blockchain, Ubuntu, iOS, Blockchain Platforms, Docker, JVM, Firebase, Amazon Web Services (AWS), Amazon EC2, AWS Lambda, Mapbox, Ethereum
  • Other

    Non-fungible Tokens (NFT), Cryptocurrency, Blockchain & Cryptocurrency, Full-stack, Cardano Blockchain, UTXO, APIs, Integration, API Integration, Smart Contracts, Responsive UI, Decentralized Finance (DeFi), Bots, Decentralized Exchanges (DEXs), Decentralized Systems, Decentralization, Plutus, Software Development, Software Architecture, Business to Business (B2B), Entrepreneurship, EUTxO, Native Assets, Google Cloud Functions, Cloud Storage, Firebase Hosting, Firebase Cloud Functions, Uber H3, Geospatial Analytics, Mapbox SDK, Trading, IPFS
  • Libraries/APIs

    React, Lombok, REST APIs, JSON-RPC, PostgREST, Firebase Web SDK, Firebase iOS SDK, Node.js, Mapbox iOS SDK
  • Tools

    Apache Maven, Terraform, Ansible, ELK (Elastic Stack), Logstash, Firebase Cloud Messaging (FCM), Xcode, Firebase Analytics, Firebase Authentication, GIS
  • Storage

    PostgreSQL, Elasticsearch, Cloud Firestore, Firebase Realtime Database, Amazon DynamoDB, Amazon S3 (AWS S3)

Education

  • Master's Degree in International Business
    2014 - 2016
    Hult International Business School - San Francisco, CA, USA
  • Bachelor of Science Degree in Applied Computer Science
    2011 - 2014
    Duale Hochschule Baden-Württemberg (DHBW) - Stuttgart, Germany

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