Leonardo is available for hire
Hire LeonardoLeonardo Pereira Papais
Verified Expert in Engineering
Full-stack Developer
São Paulo, Brazil
Toptal member since September 21, 2022
Bio
Leonardo is a senior full-stack developer with over six years of experience building back-end heavy web applications. He's a seasoned professional with an entrepreneurial mindset who's spent most of his career at startups creating reliable and scalable products. Leonardo's strongest skills are TypeScript, React, MongoDB, and AWS.
Portfolio
Pods Finance
Solidity, TypeScript, React, MongoDB
Stanley Black & Decker
TypeScript, React, Python, Docker, Three.js, Flask, Amazon Web Services (AWS)...
Cuidas
MySQL, Python, ETL, DataFrames, Mocha, React, Jest, Redux, Puppeteer, Pandas...
Experience
- Linux - 7 years
- Node.js - 7 years
- MongoDB - 7 years
- Docker - 5 years
- TypeScript - 3 years
- React - 3 years
- Python - 2 years
- Web3 - 1 year
Availability
Full-time
Preferred Environment
TypeScript, Node.js, React, MongoDB, Linux, Docker, Python, Amazon Web Services (AWS), Python 3
The most amazing...
...product that I've developed was an ERP for clinics and hospitals used to schedule over 3 million appointments and was sold to a major hospital network.
Work Experience
Senior Full Stack Engineer
2022 - PRESENT
Pods Finance
- Developed an app that monitored over 50 decentralized finance pools to track their realized returns.
- Coded an ERC4626 vault with deposit and withdrawal queues.
- Built a wrapper that converts Rebasing Tokens into Exchange Rate tokens.
Technologies: Solidity, TypeScript, React, MongoDB
Senior Full-stack Engineer
2021 - 2022
Stanley Black & Decker
- Collaborated with data scientists and product managers to develop a platform for different types of machine learning models and computer vision algorithms focused on indoor 3D reconstruction.
- Developed a TypeScript API to manage file uploads and asynchronous data processing.
- Constructed the microservices architecture on top of AWS ECS using Dockerized ML models wrapped with Flask.
Technologies: TypeScript, React, Python, Docker, Three.js, Flask, Amazon Web Services (AWS), Express.js, Amazon Elastic Container Service (ECS), Serverless Framework, Joi, PostgreSQL, Knex.js, Moment.js, SuperTest, Jest, Axios, Ramda, XState, Tailwind CSS, Webpack, APIs, ESLint, JavaScript, HTML, CSS, Web Development, Linux, Engineering, Software Development, AWS Lambda, Styled-components, Python 3, Amazon EC2, Amazon S3 (AWS S3), AWS CLI, AWS SDK, Bluebird, AWS CloudFormation, Serverless, HTML5, Full-stack
Data Scientist
2020 - 2021
Cuidas
- Worked closely with the company founders to map KPIs and build dashboards used to track metrics.
- Enhanced a Python ETL to have a broader scope by structuring the data from various sources (MongoDB, Google Calendar and Sheets, Paperform) into one MySQL deployment.
- Built a wide range of dashboards to enhance data accessibility in different teams.
- Led a team of two software developers to build machine learning models on top of our electronic health records.
Technologies: MySQL, Python, ETL, DataFrames, Mocha, React, Jest, Redux, Puppeteer, Pandas, SpaCy, APIs, ESLint, JavaScript, HTML, CSS, Web Development, Linux, Docker, Engineering, Software Development, AWS Lambda, Styled-components, Python 3, Moment.js, SuperTest, Amazon EC2, AWS Elastic Beanstalk, Amazon S3 (AWS S3), AWS CLI, AWS SDK, Bluebird, Webpack, AWS CloudFormation, HTML5, Full-stack, SQL
Software Engineer
2017 - 2019
eDoc Saude
- Worked side by side with the founding team to develop our company's business, strategy, and product; was also the first hire at the company.
- Built and deployed all our cloud infrastructure from scratch to production, making it available to be used by hundreds of health professionals and thousands of patients every day.
- Contributed to the prototyping, implementing, and enhancing of many processes like systems and architecture design, product development, quality assurance, customer onboarding, user training and support, prospect generation, sales, and so on.
- Built a system that scheduled over 3 million medical appointments.
Technologies: Node.js, AngularJS, MongoDB, Amazon Web Services (AWS), Ramda, Moment.js, Amazon EC2, AWS Elastic Beanstalk, Amazon S3 (AWS S3), Express.js, Auth0, Mongoose, Elasticsearch, Redis, Requests, Clicksign, Card Payments, Joi, Bluebird, RxJS, APIs, ESLint, JavaScript, HTML, CSS, Web Development, Linux, Docker, Engineering, Software Development, Amazon Elastic Container Service (ECS), Amazon Simple Notification Service (SNS), Amazon Simple Email Service (SES), SuperTest, AWS CLI, AWS SDK, Redux, Webpack, HTML5, Full-stack
Software Developer
2015 - 2016
Revmob
- Worked with three teams simultaneously, including the infrastructure team which reduced hosting and storage costs by testing different types of EC2 instances for each service and creating cache layers for aggregation.
- Strengthened the cloud security schema as part of the security team; also acted as the DBA of a MongoDB cluster and developed some features in Node.js, helping migrate the company's core functionality to an SOA architecture.
- Served as one of the core developers of a new database that enables ad-hoc queries in big data, written in C for the third team.
Technologies: Node.js, MongoDB, C, Column-oriented DBMS, Redis, Amazon Web Services (AWS), Mongoose, AWS CLI, AWS SDK, Amazon S3 (AWS S3), Amazon EC2, APIs, JavaScript, HTML, CSS, Web Development, Linux, Engineering, Software Development, Amazon Simple Email Service (SES), AWS Elastic Beanstalk, Requests, HTML5
Experience
Referrals at Injury.com
A React-based app focused on collecting and referring injury cases for a law firm.
I worked as a full-stack developer—coding reusable React components, AWS Lambda functions for API endpoints, and using the Serverless Framework to configure cloud resources like our Cognito User Pool. We used AWS Lambda functions running Node.js as our back end, persisting the data at DynamoDB with a single-table design.
I worked as a full-stack developer—coding reusable React components, AWS Lambda functions for API endpoints, and using the Serverless Framework to configure cloud resources like our Cognito User Pool. We used AWS Lambda functions running Node.js as our back end, persisting the data at DynamoDB with a single-table design.
Janus at Stanley Black & Decker
A measurement and documentation system that can reconstruct a 3D model of interior spaces designed for construction professionals. Users could upload videos and photos to our API endpoints and use different ML and CV models to create a reconstruction of a room.
The system was built on top of React, Three.js, AWS ECS, and AWS Lambda.
I worked as a full-stack engineer collaborating with the product manager to create the React app where users could send their photos and videos, run reconstruction models, and interact with the results. I also built our API using AWS Lambda and TypeScript and was in charge of Dockerizing and exposing ML models as web servers.
The system was built on top of React, Three.js, AWS ECS, and AWS Lambda.
I worked as a full-stack engineer collaborating with the product manager to create the React app where users could send their photos and videos, run reconstruction models, and interact with the results. I also built our API using AWS Lambda and TypeScript and was in charge of Dockerizing and exposing ML models as web servers.
Communication Pipeline at eDoc
The communication pipeline was used to send reminders and to get a confirmation/cancellation of an appointment.
I led the implementation of the project, working directly with the CTO. We built it with Express.js, Node.js, and AngularJS, chose MongoDB as our database, hosted it at AWS EC2, used Infobip.com to send SMS texts, AWS SNS to send push notifications, and AWS SES to send emails.
I used Express.js to handle webhooks with SMS responses. The company's stack consisted of Node.js, MongoDB, AngularJS, and Express.js. Therefore we used Node.js in the scripts that loaded appointments that needed confirmation to send them the appropriate communication and MongoDB to save which appointment was confirmed and which wasn't.
Over three years, we sent over 2 million SMS texts. This feature was one of the main drivers of our revenue, and it reduced the absence of patients by more than 60%, driving customer revenue up.
I led the implementation of the project, working directly with the CTO. We built it with Express.js, Node.js, and AngularJS, chose MongoDB as our database, hosted it at AWS EC2, used Infobip.com to send SMS texts, AWS SNS to send push notifications, and AWS SES to send emails.
I used Express.js to handle webhooks with SMS responses. The company's stack consisted of Node.js, MongoDB, AngularJS, and Express.js. Therefore we used Node.js in the scripts that loaded appointments that needed confirmation to send them the appropriate communication and MongoDB to save which appointment was confirmed and which wasn't.
Over three years, we sent over 2 million SMS texts. This feature was one of the main drivers of our revenue, and it reduced the absence of patients by more than 60%, driving customer revenue up.
Education
2012 - 2016
Master's Degree in Mechanical Engineering
Escola Politécnica da Universidade de São Paulo - São Paulo, SP, Brazil
Skills
Libraries/APIs
Node.js, React, Moment.js, Ramda, Zod, Requests, AWS Amplify, RxJS, Puppeteer, SpaCy, Three.js, Pandas
Tools
Amazon Elastic Container Service (ECS), SuperTest, AWS CLI, AWS SDK, Mocha, Webpack, Amazon Cognito, Amazon Simple Notification Service (SNS), Amazon Simple Email Service (SES), Knex.js, Auth0, Mongoose, AWS CloudFormation
Languages
TypeScript, JavaScript, HTML, CSS, HTML5, SQL, Python, Python 3, Solidity, C
Frameworks
AngularJS, Express.js, Serverless Framework, Jest, Redux, Flask, Tailwind CSS, Next.js
Platforms
Amazon Web Services (AWS), AWS Lambda, Amazon EC2, AWS Elastic Beanstalk, Linux, Docker, Clicksign
Storage
MongoDB, Redis, Amazon S3 (AWS S3), MySQL, PostgreSQL, Elasticsearch, Amazon DynamoDB, Column-oriented DBMS
Paradigms
ETL
Other
Engineering, Software Development, Styled-components, Joi, Axios, Zustand, Bluebird, Serverless, APIs, Web Development, Full-stack, Web3, Amazon Cognito User Pools, XState, Card Payments, ESLint, DataFrames
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