Giacomo Rebonato, Developer in Verona, Province of Verona, Italy
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Giacomo Rebonato

Verified Expert  in Engineering

Front-end Developer

Verona, Province of Verona, Italy
Toptal Member Since
July 30, 2021

Giacomo is a software engineer and team lead with a decade of experience and deep expertise in building performant front-end applications with great accessibility and intuitive UX. He has worked in numerous companies, including Zendesk and HubSpot. Giacomo values well-documented testing to ensure that every new implementation works as expected and his colleagues find him especially easy to collaborate with.


TypeScript, Serverless, Amazon Web Services (AWS), React, MobX, Jest, Datadog...
Node.js, React, Zendesk, Storybook, User Interface (UI), User Experience (UX)...
JavaScript, React, HubSpot, Unit Testing, Redux, Immutable.js, A/B Testing...




Preferred Environment

MacOS, Visual Studio Code (VS Code), React, Node.js, TypeScript

The most amazing...

...project I contributed to is Zendesk Talk, a widely used call center platform with voice calls on the browser, made by adding custom logic on top of Twilio API.

Work Experience

Team Lead

2020 - PRESENT
  • Contributed and mentored the team developing the scheduling calendar using React and MobX. Drove the scaling of the project by using TypeScript and writing well-documented unit tests with Jest.
  • Optimized Webpack configuration for faster builds and support for the latest features.
  • Introduced webpack-dev-server and its proxy for a better developer experience with no other server to run and live reload.
  • Used the Serverless Framework while contributing and mentoring a team in developing a microservices-based project for managing appointments with patients.
  • Created relevant Datadog dashboards for fine-tuning AWS Lambda performance and Jira stories for tackling technical debt.
Technologies: TypeScript, Serverless, Amazon Web Services (AWS), React, MobX, Jest, Datadog, Dashboards, AWS Lambda, Jira, Webpack, Microservices

Senior Software Engineer

2019 - 2020
  • Served on the team that renovated the UI/UX for answering calls in Zendesk Talk. Focused on accessibility and best practices, using React for navigation with keys and screen readers and Storybook to validate the UI in specific states.
  • Used Apollo for managing the state of returned data from requests for both REST and GraphQL endpoints.
  • Wrote unit and E2E tests using both Jest and Selenium to avoid regressions.
  • Continuously identified exceptions and logs from Rollbar and Datadog and created detailed Jira tickets for tackling the issues.
  • Worked closely with new hires and interns to assist them on their learning paths.
Technologies: Node.js, React, Zendesk, Storybook, User Interface (UI), User Experience (UX), Apollo, REST, GraphQL, E2E Testing, Jest, Selenium, Rollbar, Datadog, Jira

Software Engineer

2018 - 2019
  • Inherited a React codebase for the notifications menu sidebar without unit testing and raised its coverage to 70%. The sidebar is still visible on the first screen for every HubSpot user.
  • Fine-tuned React rendering performance by using Redux as a state manager and Immutable.js to ensure the immutability of the state produced by reducers.
  • Collaborated as a member of the growth team to conduct an A/B testing experiment on the customer onboarding process. Used the feature flag programming technique and reported user data on Amplitude.
  • Migrated a codebase that was using a deprecated WebSocket system to PubNub and provided integration tests that ensured the correctness of the implementation.
  • Presented a talk on React Portals during a public event in the HubSpot Dublin office, explaining how this feature can be used to create embeddable widgets, such as chats or sidebars.
Technologies: JavaScript, React, HubSpot, Unit Testing, Redux, Immutable.js, A/B Testing, Amplitude, WebSockets, PubNub, Integration Testing, Public Speaking

Software Engineer

2016 - 2018
  • Contributed to the implementation of the callback form queue feature of Zendesk Talk that was built with React on the front end and Ruby and Twilio API on the back end.
  • Used the Flux pattern to ensure that the UI was reflecting correctly in real-time UI updates during ongoing calls. Key concepts were using the store as the single source of truth and having dumb and smart components.
  • Created a Datadog dashboard to monitor the usage of features and track technical debt.
  • Tracked and fixed bugs using Jira and actively contributed to the maintenance of the Scrum board.
Technologies: JavaScript, React, Node.js, Zendesk, Front-end, Back-end, Flux, User Interface (UI), Datadog, Dashboards, Jira

Front-end Engineer

2015 - 2015
Sysnet Global Solutions (Contractor)
  • Worked on an Angular SPA that allowed customers to fill a complex form with many dynamic dependencies. All the questions were needed to achieve PCI compliance.
  • Tracked and fixed bugs, using Jira as a reporting tool.
  • Analyzed logs and exceptions, using Kibana, and created relevant stories based on my findings.
Technologies: JavaScript, Angular, TypeScript, Single-page Applications (SPA), PCI Compliance, Jira, Kibana, Front-end

Full-stack Web Developer

2012 - 2015
Wish Days
  • Developed the main eCommerce site for the Wish Days startup, using C# as back end and static HTML with Angular for the pages.
  • Created a geographic search by using MongoDB and exposing its geographic capabilities through ASP.NET Web API and created the front-end map visualization with Google Maps.
  • Wrote the database queries that were executed daily to provide useful insight to QlikView and then studied by data analysts.
Technologies: JavaScript, MongoDB, eCommerce, HTML, Angular, ASP.NET Web API, Google Maps, Front-end, Data Queries, QlikView

Web Developer

2011 - 2012
  • Worked on multiple eCommerce websites by replicating an ASP.NET form application that was created by the company and working on a custom front end with static HTML and jQuery.
  • Contributed to an ASP.NET form application for sending newsletters. This was an early Mailchimp clone.
  • Interacted with customers by phone and fixed bugs on their websites.
Technologies: JavaScript, HTML, eCommerce, ASP.NET, jQuery, Front-end

FastRat is my custom starter kit form for building full-stack applications with React and Fastify.
React is set up for SSR, which makes this setup similar to NextJS but completely open to customization and deployable everywhere.
It also contains Playwright and Github actions for running E2E tests on CI.

Advanced Developing on AWS

Amazon Web Services


React, Node.js, MobX, Rollbar, Immutable.js, PubNub, Google Maps, jQuery, Web Audio API


Jira, Webpack, Kibana


JavaScript, TypeScript, HTML, CSS, SQL, GraphQL


Jest, Selenium, Redux, Flux, Angular, ASP.NET Web API, ASP.NET, Fastify


Visual Studio Code (VS Code), Amazon Web Services (AWS), AWS Lambda, Zendesk, HubSpot, QlikView


MongoDB, Datadog


Microservices, REST, E2E Testing, Unit Testing


Front-end, Serverless, Dashboards, Storybook, User Interface (UI), User Experience (UX), Apollo, A/B Testing, Amplitude, WebSockets, Integration Testing, Public Speaking, Back-end, Single-page Applications (SPA), PCI Compliance, eCommerce, Data Queries, APIs

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