Publication
Well-structured Logic: A Golang OOP Tutorial
https://www.toptal.com/developers/golang/golang-oop-tutorial
Leonhard is available for hire
Hire LeonhardLeonhard Holz
Verified Expert in Engineering
Technical Leadership Developer
Berlin, Germany
Toptal member since July 19, 2019
Bio
Leonhard's background spans software engineering, product management, and engineering leadership. He enjoys solving problems at the intersection of technology, product, and business — making sound architectural decisions, improving engineering execution, and helping teams build software that is fit for purpose. Recently, he has focused on AI-enabled software development and engineering effectiveness.
Portfolio
Trilogy
Technical Leadership, Engineering Management, Software Architecture...
Packet Computing
Docker, Go, Linux, Amazon Web Services (AWS), Software Engineering, Python, Git
Experience One AG
Swagger, Go, SQL, Agile Software Development, Scrum, Software Engineering...
Experience
- Technical Leadership - 7 years
- Engineering Management - 7 years
- Software Architecture - 7 years
- Linux - 5 years
- Amazon Web Services (AWS) - 5 years
- Remote Work - 5 years
- Software Development Lifecycle (SDLC) - 5 years
- Artificial Intelligence (AI) - 3 years
Preferred Environment
Jira, Linux, Amazon Web Services (AWS), Docker, Java, Go, Shell, GitHub
The most amazing...
...work I’ve done was leading distributed engineering teams responsible for evolving and delivering business-critical software products used by thousands of users.
Work Experience
Vice President of Engineering
2021 - 2026
Trilogy
- Led distributed engineering teams within central engineering, responsible for delivering and operating business-critical B2B software products used by thousands of users.
- Managed up to three engineering teams through their technical leads, supporting multiple product areas with responsibility for feature delivery, maintenance, and engineering execution.
- Owned engineering outcomes across multiple software products, balancing customer needs, technical decisions, delivery priorities, and operational reliability.
- Partnered with product and business stakeholders to translate business requirements into actionable engineering initiatives and customer-facing software improvements.
- Drove architectural decisions and engineering practices across diverse technology environments, with a focus on maintainability, scalability, and effective delivery.
- Supported the adoption of AI-enabled software development practices to improve engineering productivity and help teams focus on higher-value design and problem-solving activities.
- Modernized and extended a Java intranet solution, and migrated the platform to ECS.
Technologies: Technical Leadership, Engineering Management, Software Architecture, Remote Work, Artificial Intelligence (AI), Software Development Lifecycle (SDLC), Amazon Web Services (AWS), SaaS, Claude Code, Software Engineering, Distributed Systems, CI/CD Pipelines, Code Review, Java, Agentic AI, Agentic Coding, AI Agents, AI Engineering, AI-assisted Development, Python, Large Language Models (LLMs), AI Integration, Architecture, Git, APIs, Relational Databases, Microservices, PostgreSQL, System Design
Research Assistant | Senior Software Engineer
2020 - 2021
Packet Computing
- Developed, tested, and benchmarked a distributed transactional POSIX filesystem for serverless computing.
- Enhanced system call interception of filesystem-related functions via shared objects written in C.
- Implemented semaphore- and spin-synchronized IPC communication using shared memory with C and Go.
- Ran existing benchmark applications (filebench, TPCC) in AWS EC2 and Lambda to improve performance.
- Created makefiles for building the file system and ran tests and benchmarks using Docker.
Technologies: Docker, Go, Linux, Amazon Web Services (AWS), Software Engineering, Python, Git
Senior Back-end Developer
2017 - 2020
Experience One AG
- Developed various middleware components (REST APIs) for apps and websites with Go and MongoDB/MySQL.
- Implemented a very scalable image transformation service (resize, crop, blend, convert) on top of libvips.
- Implemented a Swagger to Go generator that completely handles and hides the HTTP layer.
- Connected the websites with OAuth2 identification providers.
- Maintained an old J2EE web app using JPA 2.0 and an Oracle database.
- Modularized existing projects to enable reuse of core components and API clients.
- Encouraged dockerization, test driven development, and continuous integration.
Technologies: Swagger, Go, SQL, Agile Software Development, Scrum, Software Engineering, Distributed Systems, API Integration, Back-end, REST APIs, XML, MySQL, MongoDB, Java, API Development, Git, JavaScript, APIs, Relational Databases, System Design
Technical Co-founder and Web Developer
2015 - 2017
Online Travel Agency Startup
- Implemented the front-end in Bootstrap and jQuery.
- Developed the back-end with Java and Contentful.
- Aggregated travel offers from various sources.
- Implemented SEO for the website.
- Implemented a back-office for travel suppliers.
Technologies: Java, Software Engineering, Software Architecture, Architecture, JavaScript, System Design
Product Manager IPTV
2013 - 2015
Deutsche Telekom AG
- Conducted a feasibility study for an IPTV value proposition.
- Did a feasibility study and implementation plan for the IPTV "Instant Replay" feature.
- Investigated and compiled market research for IPTV products.
- Compared TV and media related recommendation engines.
Technologies: Feasibility Studies, Market Research
Technical Project Manager
2010 - 2013
Deutsche Telekom AG
- Managed an external development team for a social TV guide using Scrum.
- Oversaw the T-Systems team building a virtual set-top box using Scrum.
- Recruited and managed a freelance team developing a social digital products platform.
Technologies: Jira, Technical Leadership, Engineering Management, Software Architecture, Agile Software Development, Architecture
Web Developer
2005 - 2010
McTec, Ltd.
- Enhanced websites of Axel Springer newspapers built on top of PHP CMS.
- Built special-interest PHP microsites and apps like DPA reader.
- Built a web app for Axel Springer's newspaper pre-print verification.
- Developed for a migration project from PHP CMS to Java CMS for two major Axel Springer newspapers in Germany.
- Led the technical aspects of the implementation of polish newspaper website on top of Java CMS.
- Oversaw technical projects related to the introduction of streaming media content to Axel Springer newspaper websites.
Technologies: Linux, Java, SQL, Software Engineering, JavaScript, APIs, Relational Databases
Experience
Education
2015 - 2020
Bachelor's Degree in Cultural Studies
University of Hagen - Hagen, Germany
2000 - 2005
Master's Degree (Dipl.-Informatiker) in Computer Science
University of Hagen - Hagen, Germany
Skills
Libraries/APIs
REST APIs, API Development
Tools
Git, Jira, Shell, GitHub, Claude Code
Platforms
Linux, Amazon Web Services (AWS), Docker
Languages
Go, Java, SQL, XML, Python, JavaScript
Frameworks
Swagger
Paradigms
Agile Software Development, Scrum, Microservices
Storage
MySQL, Relational Databases, MongoDB, PostgreSQL
Other
Technical Leadership, Engineering Management, Software Architecture, Remote Work, Software Development Lifecycle (SDLC), Software Engineering, Architecture, Artificial Intelligence (AI), Distributed Systems, CI/CD Pipelines, Code Review, API Integration, Back-end, Agentic AI, Agentic Coding, AI Agents, AI Engineering, AI-assisted Development, Large Language Models (LLMs), AI Integration, APIs, System Design, Computer Science, History, Feasibility Studies, Market Research, Philosophy, SaaS
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