Mario Saly, Developer in Budapest, Hungary
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Mario Saly

Verified Expert  in Engineering

Full-stack Developer

Budapest, Hungary
Toptal Member Since
January 26, 2024

Mario is a highly skilled front-end engineer with an extensive background in the software industry. With over five years of experience working with different technologies, programming languages, and frameworks, he is an expert in the most recent technologies of the web industry. Passionate about IT, Mario enjoys being challenged, expanding his knowledge, and enhancing his skills while solving clients' problems.


TypeScript, React, Node.js, Next.js, Pulumi, Amazon Web Services (AWS)
React, Node.js, TypeScript, Material UI, Apollo Server, React Apollo, GraphQL...
React, Node.js, TypeScript, Material UI, GraphQL, Apollo Server, React Apollo...




Preferred Environment

React, TypeScript, Node.js, Next.js, NestJS, PostgreSQL, NoSQL, GraphQL

The most amazing...

...thing I've developed is a web application called Plandek that provides impressive engineering analytics for teams.

Work Experience

Full-stack Developer

2022 - 2023
  • Analyzed the existing codebase and improved it according to the rules of React (e.g., fixed the wrongly used hooks and anti-patterns and issues in code style).
  • Implemented full synchronization between our database and billing provider, ChargeBee, using webhooks.
  • Migrated all of the current back-end and front-end projects to a mono repo using Turborepo and fully integrated Pulumi (TypeScript) to make deployment to AWS easier for engineers.
  • Set up a new back-end project from scratch and built an API that integrates with an IDV SDK and provides end-to-end identity verification for a huge crypto wallet provider.
  • Dealt with plenty of DevOps-related tasks, so I learned a ton about AWS features (ECS Fargate, S3, KMS, SQS, SNS, and Lambdas).
Technologies: TypeScript, React, Node.js, Next.js, Pulumi, Amazon Web Services (AWS)

Full-stack Software Engineer

2021 - 2022
  • Cleaned up the previous project as a member of a 3-man team and helped find all sorts of optimizations and refactoring possibilities.
  • Took on the responsibility for identifying the main performance issues, using various tools and debugging methods to fix them.
  • Integrated the design process and implementation of a new core feature of Plandek.
  • Finished up the changing of a core library to a newer and better functioning one, cleaned up the unnecessary code, refactored components, and removed the old dependencies.
  • Set up the application performance monitoring (APM) on the back end and real user monitoring (RUM) on the front end.
  • Worked with the enablement team experimenting with new tools and packages to research which one fits the team's needs the most.
Technologies: React, Node.js, TypeScript, Material UI, Apollo Server, React Apollo, GraphQL, Jira, JavaScript, PostgreSQL, Elasticsearch, Application Performance Monitoring

Full-stack Software Engineer

2020 - 2021
  • Explored solutions to complex issues on a daily basis, which led to the development of high-level problem solving and debugging skills.
  • Played a key role in technology, being highly involved in development-related questions during product discussions.
  • Developed a live chat feature for the platform using the key features of Apollo GraphQL, like subscriptions, optimistic UI, and client-side caching functionalities.
  • Built a room-based group call functionality based on WebRTC with a widely used peer-to-peer connection npm package. Also implemented many other features for rooms, like kick and ban, permissions (guest, admin, and member), and more.
  • Set down the basics of analytics sending implementation on both the front and back end. Integrated Google Analytics and, later on, Amplitude to gather site analytics. Also added and set up Sentry for crash reporting.
  • Integrated Google Cloud to store images and files and worked on countless other performance optimizations on the entire stack, required due to the constantly growing user base.
Technologies: React, Node.js, TypeScript, Material UI, GraphQL, Apollo Server, React Apollo, MongoDB, Mongoose, Styled-components, Peer-to-peer Networking, JavaScript, Firebase

Software Engineer

2019 - 2020
  • Implemented several near-range camera system features, which provides rear and surround camera view for modern cars. Land Rovers and Jaguars are using this system.
  • Worked with an extremely high-level project management system in Jira while learning how Jira works in an enterprise company with thousands of employees.
  • Integrated a group of specially selected professionals from different teams and seniority to work on a brand new product that assists the car drivers with parallel parking.
  • Collaborated with the team in developing an AI with cutting-edge technologies for finding parking slots using only the car's camera system.
Technologies: C, C++, Python, Jira, Jenkins

Full-stack Engineer

2018 - 2019
Narrativ Film, Budapest
  • Maintained a web application that was built using React and React-Bootstrap.
  • Developed a back end for the web application with authentication and authorization, so users could register to the platform and check out information about movies.
  • Added admin role-specific endpoints to the back end and developed an admin panel, so users with this role could manage other users and platform functionalities from that dashboard.
Technologies: React, React-Bootstrap, NestJS, TypeScript, Node.js, MongoDB, JavaScript, Next.js

Plandek | End-to-end Engineer Analytics
I had the privilege of contributing to a groundbreaking value-stream management product centered around software engineer analytics, providing invaluable insights for enhanced project management and productivity.

As a key member of the enablement team, my responsibility was to pioneer new tools for future feature implementations. This involved evaluating and selecting optimal solutions such as charting libraries and performance monitoring tools.

A significant portion of my efforts went into addressing performance issues on the dashboards, resulting in substantial improvements in loading and rendering times, significantly enhancing the overall user experience.

A highlight of my contribution was my active involvement in designing the "Standup View" feature, which became one of the product's cornerstones.

Upon concluding my tenure, I left with a strong professional bond with the CTO, maintaining an ongoing relationship. Post-employment, I've continued to contribute by referring three highly skilled engineers who seamlessly integrated into the team.

Bindr App | Helps Students to Study Together Online

I was the first engineer joining Bindr to work with the founders in developing their MVP. The application included peer-to-peer group video calls called "study sessions" and live chat functionality, integrating external SDKs afterward. The app contains other features, such as automated emails, WebSocket events, and the scheduling of recurring sessions for specific times.

We had to set up a robust base both for the back and front end, one that could handle tens of thousands of users a couple of months later. We faced challenging problems, found solutions, and addressed the rapidly growing user base. Meanwhile, new engineers were joining the team. I helped the CTO with the onboarding of these new developers while managing a smaller group of new engineers, reviewing their work daily.

I have an excellent relationship with the founders, and I still support them whenever I can. Because I wrote a big part of the codebase, we sometimes have to discuss further ideas or questions.
2017 - 2020

Bachelor's Degree in Computer Science

Eötvös Lóránd University - Faculty of Informatics - Budapest, Hungary


React, Node.js


Jira, Slack, React Apollo, Mongoose, Jenkins


TypeScript, GraphQL, JavaScript, HTML, CSS, C, C++, Python


Material UI, React-Bootstrap, NestJS, Express.js, Next.js


Visual Studio Code (VS Code), MacOS, Firebase, Amazon Web Services (AWS)


MongoDB, PostgreSQL, Elasticsearch, NoSQL


Software Development, Apollo Server, Styled-components, Front-end, Peer-to-peer Networking, Pulumi, AmCharts, Application Performance Monitoring

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