Juan Mendoza, Developer in Berlin, Germany
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Juan Mendoza

Verified Expert  in Engineering

Software Engineering Developer

Berlin, Germany
Toptal Member Since
November 9, 2022

Juan is a self-motivated software engineer and a certified AWS architect. With more than 14 years of experience in software engineering, leading and being part of successful cross-functional teams, Juan loves to work in close collaboration with the product and design teams to achieve the company goals and OKRs.


React, Next.js, NPM, TypeScript, CircleCI, CI/CD Pipelines, GitHub, Bitbucket...
Delivery Hero
Ruby on Rails (RoR), Spring Boot, Kotlin, React, Node.js, Microservices...
Delivery Hero
Management, Software Engineering, TypeScript, REST APIs, Docker, Docker Compose...




Preferred Environment

Spring Boot, Java, Kotlin, Node.js, React, Amazon Web Services (AWS), Kubernetes, Terraform, PostgreSQL, Next.js

The most amazing...

...projects I've delivered helped companies reach their goals by splitting monolith systems into microservices or creating scalable solutions.

Work Experience

Lead Software Developer

2023 - PRESENT
  • Developed a proof of concept for main public pages using Next.js 13, React, and Typescript to boost performance and organic traffic, reducing the page loading time from around 20s to 0.9s using server side rendering and infinite scrolling on the client side.
  • Implemented a new set of end-to-end (E2E) test suites to improve the quality of the project using Playwright, TypeScript, and Page Object Models, covering most of the main user flows on the site.
  • Created automation to set up local environments for new developers, reducing the onboarding time from around four days to less than an hour, using a combination of homebrew and shell tools.
  • Improved existing and new pipelines on our CI/CD to assure quality at all stages of the development cycle by running in parallel all the tests of the project and also guaranteeing that all projects are properly built without errors on CircleCI.
  • Shared knowledge with all front end engineers on the use of Playwright and TypeScript as an E2E testing tool in several workshops.
  • Increased code quality across projects by leveraging multiple code quality tools, such as Husky, Prettier, ESlint, lint-staged, and TypeScript, making all of these technologies work together without disrupting the current developer experience.
  • Interviewed several candidates as one of the final steps of the hiring process for senior front-end and full-stack developers for the teams in the organization.
Technologies: React, Next.js, NPM, TypeScript, CircleCI, CI/CD Pipelines, GitHub, Bitbucket, CSS, HTML, JavaScript, Go, Shell, Playwright, E2E Testing, Jest, Amazon Web Services (AWS), Amazon S3 (AWS S3), Amazon Elastic Container Registry (ECR), Amazon Elastic Container Service (Amazon ECS), Amazon CloudFront CDN, MongoDB, DocumentDB, Amazon EKS, Technical Leadership, Automation, Containerization, Containers, Responsive Web Design (RWD), HTML5, Leadership, Full-stack Development, SQL, AWS Lambda, AWS Fargate, CSS3

Staff Software Engineer

2021 - 2023
Delivery Hero
  • Developed a product from scratch that generates landing pages that are deployed in all continents and in more than 60 countries, using Gatsby, TypeScript, Cloudflare, AWS S3, and more AWS services.
  • Improved CronJobs on a legacy service using Ruby, Rails, PostgreSQL, and Kubernetes to fine-tune database interactions and redesign some of the CronJobs to add more granularity to the execution, reducing database instances and costs by 50%.
  • Migrated two services (1,000 rpm) from a regional base to a country base without downtime. Implemented missing functionality, created new instances, migrated data, switched the API gateway, and imported delta data files.
  • Implemented AWS Lambda functions to replace the short URLs external providers widely used in the Delivery Hero ecosystem, saving over €1.000 per month. Used AWS Lambda, Node.js, Terraform, and Kong API Gateway.
  • Created a new microservice to generate static landing pages, deprecating external providers and reducing over €5.000 in monthly costs, and improving the conversion rate by 60%. Used Spring Boot, Kotlin, React, Gatsby Drone CI, AWS S3, and Cloudflare.
  • Contributed to our load-test suite with several test scenarios where we tried to put our services under a lot of stress by simulating multiple requests growing exponentially, reaching our goal of handling 10x peak load, using Scala and Gatling.
  • Redesigned all landing pages for all the different brands of Delivery Hero across the globe in 60 countries. We achieved this by offering full customization in terms of design, images, colors, fields, language, etc.
Technologies: Ruby on Rails (RoR), Spring Boot, Kotlin, React, Node.js, Microservices, Kubernetes, Helm, Terraform, PostgreSQL, Gatsby, Drone CI, Amazon S3 (AWS S3), CSS, Software Engineering, Spinnaker, Redux-Saga, REST, Kong, TypeScript, REST APIs, Docker, Docker Compose, Front-end, Redux, Amazon Web Services (AWS), AWS Cloud Architecture, Architecture, Enterprise Application Architecture, Full-stack, Storybook, Bootstrap, JavaScript Testing, Figma, Webpack, Ruby, Rust, Shell, JavaScript, Scala, Gatling, Load Testing, Technical Leadership, Automation, HTML5, Containers, Containerization, Responsive Web Design (RWD), NPM, Leadership, Full-stack Development, SQL, AWS Lambda, HTML, CSS3

Engineering Manager

2020 - 2021
Delivery Hero
  • Facilitated a work environment where my teams could share ideas and perform their best by promoting communication, removing roadblocks, listening to feedback on issues, and more.
  • Conducted weekly one-on-one meetings and guided and mentored my team to grow their soft and technical skills, which resulted in six promotions in the individual contributor career path and one in the managerial career path.
  • Defined hiring funnels for different positions in the logistics workforce. Achieving our ambitious hiring goals for six quarters in a row.
Technologies: Management, Software Engineering, TypeScript, REST APIs, Docker, Docker Compose, Front-end, Redux, Amazon Web Services (AWS), AWS Cloud Architecture, Architecture, Enterprise Application Architecture, Full-stack, Storybook, Bootstrap, JavaScript Testing, Figma, Cypress, Webpack, Technical Leadership, Responsive Web Design (RWD), Containers, Containerization, HTML5, NPM, JavaScript, Leadership, Full-stack Development, SQL, Ruby, AWS Lambda, HTML, CSS3

Engineering Lead

2017 - 2020
  • Split a monolithic application enhancing the first component of the recruitment process with an improvement of 50% in the loading time and 10% in the conversion rate, using React, Jest, and Puppeteer.
  • Created a component library used across different teams, reducing the development time and achieving a better look and feel on all parts of the application. Here we used React, Emotion, and Storybook.
  • Defined the scope of the project and implemented a new redesign, making sure that the whole team met our commitments on time, achieving close to 100% on-time delivery of all features assigned to the team.
  • Shared knowledge by giving different workshops on front-end technologies such as React, Redux, styled-components, and Puppeteer, and on back-end technologies such as Kotlin, CircleCi, and Docker Compose.
  • Conducted one-on-one weekly meetings and evaluated individual contributions.
  • Redesigned the onboarding funnel completely, also called new user registration, where we used a mobile-first approach and created a set of reusable components that later would improve the development speed of other teams.
Technologies: Spring Boot, Java, Groovy, Grails, React, Styled-components, Management, Software Engineering, Engineering Management, TypeScript, REST APIs, Docker, Front-end, Redux, Amazon Web Services (AWS), AWS Cloud Architecture, Architecture, Enterprise Application Architecture, Full-stack, Storybook, Bootstrap, JavaScript Testing, Technical Leadership, Responsive Web Design (RWD), Containers, Containerization, HTML5, NPM, JavaScript, Leadership, Full-stack Development, SQL, HTML, CSS3

Senior Software Engineer

2015 - 2017
  • Implemented a recommendation engine based on user activity that helped engineers and sales teams find relevant information more efficiently.
  • Developed an end-to-end testing framework with Selenium, Gradle, and Java 8 that considerably reduced the number of regression bugs.
  • Built a cross-platform mobile application prototype with the same capabilities as a desktop site allowing engineers to manage all their tasks on their mobile devices. Using Ionic Framework, Angular, and Cordova.
  • Created a React application to request and deliver feedback on the quality and relevance of the articles in the knowledge database widely used by support and sales engineers.
Technologies: Java, React, Apex, Oracle, Oracle Database, REST, Selenium, Ionic, Angular, PL/SQL, Spring MVC, Apache Maven, Gradle, REST APIs, Full-stack, Bootstrap, Cordova, AngularJS, Responsive Web Design (RWD), HTML5, NPM, JavaScript, Full-stack Development, SQL, HTML, CSS3

Senior Java Developer | Technical Lead

2012 - 2015
Internet Brands
  • Implemented a feature to compare cars increasing daily visits from 1,000 to 10,000 users, using Vanilla JavaScript, HTML, CSS, and REST services.
  • Created an email campaign and templating engine that sends emails to users based on their interests in vehicles or articles on the site, fully compliant with all email clients and sites.
  • Collaborated and mentored a team from the USA, Uruguay, India, and Mexico in redesigning one of the top three sites of car sales in the USA.
Technologies: Java, Groovy, Apache Velocity, CSS, HTML, Oracle Database, JavaScript, jQuery, Spring MVC, REST APIs, Front-end, Full-stack, Bootstrap, Full-stack Development, Technical Leadership, MySQL, Responsive Web Design (RWD), Leadership, SQL, CSS3

Software Development Engineer

2010 - 2012
NIC Mexico
  • Completed search, registration, and management of domain names with the .mx country code top-level domain (ccTLD).
  • Created a parser to consume reports of payments from several bank institutions and register fulfilled transactions.
  • Trained members on front-end technologies and JavaServer Faces (JSF) framework.
Technologies: Java, JSF, JavaScript, CSS, HTML, Oracle Database, Full-stack, Full-stack Development, SQL

Software Engineer Intern

2008 - 2010
  • Developed a site that showed the grade of the students on a specific test.
  • Implemented a registration application that tracked student assistance using a barcode.
  • Created an application for the teachers to upload and format data of students' grades.
Technologies: Java, Jakarta Server Pages (JSP), jQuery, JavaScript, PHP, Visual Basic, AccessData, HTML

Software Engineer Intern

2008 - 2009
  • Implemented a module to support multiple languages throughout the application, allowing users to translate into any language, when previously it was just English <> Spanish.
  • Developed a new CMS module to create static content as landing pages.
  • Simplified several modules of our custom CMS which helped with code maintainability and reduced bugs overall.
Technologies: PHP, CakePHP, JavaScript, jQuery, Linux, LAMP, Apache, MySQL, CSS, HTML

Miinimalist Personal Website

I created an extremely minimalist site in less than a day using Gatsby, React, TypeScript, Cloudflare, AWS S3, and pnpm. I had been postponing the creation of a portfolio site and one that could contain all the places where people can contact me. I finally managed to do a quick proof-of-concept, and this is the result.

Landing Page and Registration of New Users

A React, Redux, and styled-components application that was split from a monolithic service. We improved the front-end stack, introducing React and Redux for user enrolment and to the whole European branch of the company, reducing load time by 50% and improving the completion rate by 10%. I was involved in the plan, design, implementation, and delivery phases of this project.

Dodo: Static Landing Page Creator

Dodo is a static landing page creator developed to replace the existing WordPress solution. In the back end, we used Kotlin, Spring Boot, and PostgresSQL, while in the front end, we used React and Gatsby. To generate and publish the pages, we are using Drone CI. I participated on both sides of the application development process. The Rider Food Panda is an example of a page developed with Dodo.


Java, CSS, HTML, JavaScript, SQL, HTML5, Kotlin, TypeScript, Ruby, CSS3, Python, Groovy, Apex, Go, Rust, Scala, PHP, Visual Basic


Bootstrap, Spring Boot, Redux, Cypress, Ruby on Rails (RoR), Grails, Selenium, Ionic, Angular, Spring MVC, Apache Velocity, JSF, Jest, Next.js, CakePHP, AngularJS, Jakarta Server Pages (JSP)


React, REST APIs, Node.js, jQuery, Redux-Saga, Playwright


JavaScript Testing, Kong, Docker Compose, Figma, Helm, Terraform, Flyway, Apache Maven, Gradle, Google Analytics, Webpack, NPM, CircleCI, GitHub, Bitbucket, Shell, Amazon Elastic Container Registry (ECR), Amazon Elastic Container Service (Amazon ECS), Amazon CloudFront CDN, AWS CLI, Gatling, Apache, Amazon EKS, AWS Fargate


REST, Enterprise Application Architecture, Responsive Web Design (RWD), Microservices, Management, E2E Testing, Load Testing, Automation


Amazon Web Services (AWS), Oracle, Docker, Kubernetes, Drone CI, Spinnaker, Oracle Database, Linux, LAMP, AccessData, AWS Lambda


Software Engineering, Programming, Software Architecture, Front-end, AWS Certified Solution Architect, AWS Cloud Architecture, Architecture, Full-stack, Storybook, Technical Leadership, Full-stack Development, Leadership, Containers, Gatsby, Computer Vision, AI Programming, Neural Networks, Artificial Intelligence (AI), API Gateways, Styled-components, Engineering Management, CI/CD Pipelines, PNPM, Cloudflare, Cordova, DocumentDB, Containerization


PostgreSQL, Amazon S3 (AWS S3), PL/SQL, MongoDB, MySQL

2005 - 2009

Bachelor's Degree in Computer Science

Instituto Tecnológico y de Estudios Superiores de Monterrey (ITESM) - Monterrey, Mexico


Computer Vision Expert | Nanodegree Program



Reactive Architecture: Domain Driven Design - Level 2



Course Artificial Intelligence Foundations: Neural Networks

LinkedIn Learning


Reactive Architecture: Reactive Microservices - Level 2



Reactive Architecture: Introduction to Reactive Systems - Level 2



AI Programming with Python | Nanodegree Program



AWS Certified Solutions Architect Associate


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