Marcell Tóth, Developer in Budapest, Hungary
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Marcell Tóth

Verified Expert  in Engineering

Full-stack Developer

Budapest, Hungary
Toptal Member Since
August 16, 2021

Marcell is a full-stack developer with several years of experience developing various projects from CLI tools to enterprise web applications. In the last few years, Marcell has been focusing on front-end development with React and TypeScript while also engaging in leadership duties. In his free time, Marcell keeps up to date on the latest technologies and architectural patterns so that he can construct the best solution that meets his client's needs—both in terms of UX and code quality.


Stoplight, Inc.
JavaScript, TypeScript, React, MobX, Git, OpenAPI, Node.js, Jest, Webpack...
C#, Windows Store, PHP, MySQL, HTML5, CSS, JavaScript, ASP.NET...
Appsint Ltd.
ASP.NET Core, C#, JavaScript, TypeScript, React, Redux, Webpack, SQL...




Preferred Environment

Windows Subsystem for Linux (WSL), IntelliJ IDEA, WebStorm, Git, Slack, GitHub

The most amazing...

...project I've worked on is an API documentation library called Stoplight Elements which auto-generates a beautiful documentation site for your API.

Work Experience

Senior Software Engineer | Team Lead

2020 - PRESENT
Stoplight, Inc.
  • Collaborated closely with the product team to ensure the success of Stoplight Elements, our new open-source initiative.
  • Facilitated Scrum ceremonies and led technical discussions while also working as an individual contributor—ensuring the project's quality and timely delivery.
  • Built an open-source library that powered the API documentation portals of big enterprises and small companies alike.
Technologies: JavaScript, TypeScript, React, MobX, Git, OpenAPI, Node.js, Jest, Webpack, Web Components, Agile Software Development, REST APIs, GraphQL, PostgreSQL, CSS, SQL, Databases, Performance, Scaling, Front-end, User Interface (UI), GitHub, UI Components, Front-end Development, Team Leadership, Technical Leadership, Software Architecture, Architecture, SaaS, APIs, HTML, JSX

Freelance Developer

2010 - PRESENT
  • Took on several freelance projects, ranging from custom websites to data-processing tools for accounting firms.
  • Published applications to the Windows and the Google Play stores, such as a study-management app used by thousands of students or another one used in advanced pilot-training.
  • Regularly mentored junior developers on an online tutoring platform, helping them advance in their careers and working with them to unblock a project should they get stuck with anything.
Technologies: C#, Windows Store, PHP, MySQL, HTML5, CSS, JavaScript, ASP.NET, Windows Presentation Foundation (WPF), Windows Forms (WinForms), Bash Script, React, Redux, Team Mentoring, Git, Node.js, TypeScript, Next.js, SQL, Databases, REST APIs, Front-end, User Interface (UI), GitHub, UI Components, Front-end Development, Software Architecture, Architecture, SaaS, Jest, Serverless Architecture, .NET Core, APIs, HTML, Amazon S3 (AWS S3), JSX, NestJS

Senior Full-stack Engineer | Team Lead

2018 - 2020
Appsint Ltd.
  • Led the transition from a legacy ASP.NET Web Forms UI to React to enable new features.
  • Mentored junior developers, facilitated sprint planning, reviewed code, and so on.
  • Advised management in technology-related decisions.
Technologies: ASP.NET Core, C#, JavaScript, TypeScript, React, Redux, Webpack, SQL, Microsoft SQL Server, MySQL, Git, CSS, Databases, REST APIs, WebSockets, Performance, Scaling, Front-end, User Interface (UI), GitHub, UI Components, Front-end Development, Team Leadership, Technical Leadership, Software Architecture, Architecture, SaaS, .NET Core, APIs, HTML, JSX

Full-stack Engineer

2017 - 2018
  • Contributed to the build of an in-house framework powering multiple enterprise systems.
  • Worked closely in an Agile environment with product owners to deliver perfect solutions that met our customers' needs.
  • Assisted multiple large enterprise customers (including banks and government entities) with their on-premise installation needs and problems.
Technologies: ASP.NET MVC, C#, JavaScript, jQuery, SQL, Microsoft SQL Server, Git, CSS, Databases, REST APIs, WebSockets, Performance, Scaling, Front-end, User Interface (UI), GitHub, UI Components, Front-end Development, Software Architecture, Architecture, SaaS, .NET Core, APIs, HTML

Software Engineer

2015 - 2016
IT-Runner Ltd.
  • Worked as the sole developer in an IT operations firm and handled almost every case where the customer needed a custom software tool to solve their unique problem.
  • Worked with a wide variety of programming languages and environments, ranging from VBA macros to a mass-email-delivery PHP application.
  • Serviced and supported Linux and Windows-based servers and networking hardware.
Technologies: PHP, JavaScript, HTML5, CSS, Linux, Bash Script, Linux Administration, Windows Server, SQL, Databases, GitHub, Front-end, Front-end Development, Software Architecture, SaaS, Windows Forms (WinForms), HTML

Stoplight Elements
Stoplight Elements is a library that takes your OpenAPI specification and renders a beautiful documentation site. It is an alternative to well-known tools like Swagger UI or Redocly.

I served as the team lead responsible for this nine-month-long project, and scope extensions aside, under my leadership, we delivered everything predictably and on time while maintaining a high-quality standard. The domain is technically challenging, with problems ranging from providing a pixel-perfect UI design to parsing YAML, resolving REFs, and building an HTTP request maker UI.

My responsibilities span way beyond just writing and reviewing code. We had to design everything from the ground up, including technical aspects like a CI/CD pipeline, testing strategy, and soft problems like collaborating with marketing and sales.\

Enterprise eCommerce for Lick
Lick Home Ltd. is a UK startup to revolutionize the home decor industry. Instead of the traditional retail channels, they set out to sell paint, wallpaper, and accessories through a highly modern, custom-built eCommerce store.

I was augmenting Lick's agile engineering team, implementing new features with them, and providing support and advice in more specialized areas, like architecture design, CI/CD, or test automation.

The store is using Shopify Plus for the checkout process but has a separate headless CMS and a custom-built REST API in front, with a NextJS front-end providing the user interface. We started implementing more advanced patterns, like AWS lambdas, managed queues, and API gateways as the company grew.

B2B Workflow Automation for a US eCommerce Wholesaler
Slightly different from the SaaS projects I'm usually involved in, I had the opportunity to work with the US personal care brand Lovery. As Lovery launched as a small family business, it used a lot of tedious manual processes behind the scenes to handle inventory, sales, and fulfillment across multiple selling channels. As they scaled, the team started to hit the limits of manual processing of orders, especially nearing the holiday season.

I worked with the Lovery team and their partners to automate many of their processes using industry-standard protocols and procedures. As a result, their need for manual labor to process orders was reduced tremendously, along with much-improved processing times.
2016 - 2019

Bachelor's Degree in Business Information Systems

Corvinus University of Budapest - Budapest, Hungary


Microsoft Certified Professional



React, Node.js, REST APIs, MobX, OpenAPI, jQuery, Windows Forms (WinForms), Redox


Git, GitHub, JSX, WebStorm, Webpack, Slack, Shopify Plus, Amazon Simple Queue Service (SQS), Amazon CloudFront CDN, CircleCI, Jira


.NET, ASP.NET Core, Jest, Next.js, .NET Core, Redux, NestJS, ASP.NET MVC, ASP.NET, Windows Presentation Foundation (WPF), Express.js, Cypress, Swagger, Blazor


C#, JavaScript, TypeScript, CSS, HTML, SQL, PHP, HTML5, Bash Script, GraphQL, SCSS


PostgreSQL, Databases, Amazon S3 (AWS S3), Microsoft SQL Server, MySQL


Serverless Architecture, Agile Software Development, Unit Testing, Agile, Scrum, Kanban


Linux, AWS Lambda, Amazon Web Services (AWS), Windows Server, Shopify


CI/CD Pipelines, Performance, Front-end, UI Components, Front-end Development, Technical Leadership, Software Architecture, Architecture, SaaS, Content Management Systems (CMS), APIs, System Design, Team Leadership, WebSockets, Scaling, User Interface (UI), Windows Subsystem for Linux (WSL), Web Components, Linux Administration, Windows Store, Team Mentoring, API Design, Serverless, Scrumban, Styled-components, CSS-in-JS, Data Visualization, eCommerce, Electronic Data Interchange (EDI)

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