Leo Esaki, Software Developer in Tokyo, Japan
Leo Esaki

Software Developer in Tokyo, Japan

Member since September 7, 2017
Leo is a talented and passionate full-stack developer with a focus on front-end development with React and Angular. He is also strong in building mobile apps with React Native and specializes in dynamic languages such as JavaScript, Python, Ruby, PHP, etc. Leo is passionate about working with motivated teams and getting things done. Currently, he prefers to work with React and Redux. He strictly adheres to the DRY principle and KISS approach.
Leo is now available for hire

Portfolio

Experience

Location

Tokyo, Japan

Availability

Part-time

Preferred Environment

PyCharm, Atom, Sublime Text, Git, MacOS, Ubuntu, Visual Studio Code

The most amazing...

...project I've worked on is a fintech platform that provides a portfolio management solution with intuitive dashboards and a console for clients and advisors.

Employment

  • React Native Cross Platform Mobile App Developer

    2020 - 2021
    My Roadmap (Via Toptal)
    • Built pixel-perfect pages using React following the designs given by Adobe XD.
    • Updated code layout for better maintenance, particularly for the Redux part.
    • Worked on building a mobile app for iOS and Android using React Native from React code by using Ionic React and implemented push notifications and deep links.
    Technologies: React, Redux, React Native, Django REST Framework, ECMAScript (ES6), Slack, HTML5
  • Senior Full-stack Developer

    2020 - 2020
    Ready Education (via Toptal)
    • Developed several pages in pixel-perfect from the Figma design using Angular 8.
    • Integrated with phrase.com for internationalization.
    • Used NgRx for state management and integrated it with a RESTful API written with Python Flask.
    • Performed test-driven development using Jasmine, Karma, and CI/CD with a GitLab pipeline.
    Technologies: Flask, Angular, Front-end, Full-stack, CSS, ECMAScript (ES6), Slack, Teamwork, HTML5
  • Senior React Engineer

    2020 - 2020
    Defy Gravity Inc. (via Toptal)
    • Integrated with Firebase API for efficient data storage.
    • Implemented the clipboard functionality of the text editor.
    • Applied routing features between chip elements and routes.
    Technologies: WebGL, TypeScript, React, Front-end, CSS, ECMAScript (ES6), Slack, Teamwork, HTML5
  • React Front-end Engineer

    2019 - 2020
    Toptal (via Toptal)
    • Joined the SEO development team of a Toptal core project.
    • Implemented sticky header navigation for the freelance calculator page.
    • Worked on optimizing JavaScript bundle sizes for CMS pages.
    • Applied the lazy-loading of images to reduce the initial load time.
    • Reimplemented the dropdown component to meet the W3C ARIA requirements.
    • Fixed the various UI layout issues in more optimized ways.
    Technologies: Content Management Systems (CMS), Node.js, Search Engine Optimization (SEO), Server-side Rendering, React, Ruby on Rails (RoR), HTML, REST APIs, Front-end, CSS, ECMAScript (ES6), Slack, Teamwork, HTML5
  • Experienced React Developer

    2019 - 2019
    Altitude Networks Inc (via Toptal)
    • Refactored the file risk management platform to use the latest stacks specific to each version.
    • Implemented an API call with cancelable promises using React Hooks.
    • Executed the tracking of analytics through Sentry and back-end API calls.
    • Reimplemented several UI components based on the new mockups.
    • Applied the exporting of large table data as CSV by customizing Griddle.
    • Wrote unit tests using Jest and added snapshot tests to all the UI components.
    • Built a marketing site including a landing page with Metalsmith site generator.
    Technologies: Lodash, Continuous Integration (CI), Sentry, OAuth, Metalsmith, Bootstrap, AWS Amplify, Jest, TypeScript, React, HTML, REST APIs, Front-end, CSS, Functional Programming, ECMAScript (ES6), SSH, ES7, Slack, Teamwork, HTML5
  • React Developer

    2019 - 2019
    Listing Loop Pty Ltd (via Toptal)
    • Built an admin management web app for the property listing platform with React and TypeScript.
    • Developed the responsive mobile screens of the buyer app for the real estate platform.
    • Fixed a slow performance issue with a lagging UI on mobile devices.
    • Implemented the pagination with infinite loading for the properties list.
    • Handled the implementation of the Firebase DB migration scripts in JavaScript.
    • Ensured the components and redux-saga modules were thoroughly tested with Jest.
    Technologies: Mapbox GL, Styled-components, Jest, Firebase, React Router, Formik, Redux-saga, TypeScript, Redux, React, HTML, React Redux, REST APIs, Front-end, CSS, Functional Programming, ECMAScript (ES6), SSH, Slack, Teamwork, Chatbots, HTML5, Next.js
  • Mobile and Web Developer | React Native and AngularJS

    2018 - 2019
    Lithic
    • Contributed to the front-end of the mobile and web apps with React Native and AngularJS.
    • Added new screens for the onboarding flow to the mobile app built with React Native.
    • Improved the card details screen based on the new mockup.
    • Updated the React Native and dependencies version of the legacy mobile app to the current versions.
    • Added the new UI pages for the onboarding flow to the web app built on the MEAN stack.
    • Improved the card details page based on the new mockup.
    Technologies: Pug, AWS SDK, Express.js, Moment.js, Grunt, AngularJS, MEAN Stack, Redux, React Native, HTML, REST APIs, Front-end, CSS, Slack, Teamwork, iOS
  • Full-stack Developer

    2018 - 2018
    Open Polytechnic of New Zealand (via Toptal)
    • Refactored the old AngularJS learners dashboard page into Angular 5.
    • Implemented the proof of concept feature for learners to set custom course start and end dates.
    • Restructured the old integration tests written in Mocha into WDIO (WebDriverIO) tests to run multiple tests simultaneously.
    • Handled the portfolio or course model structure migration and refactored the related API endpoints.
    • Ensured that multiple reviewers could be added to the courses.
    Technologies: Mocha, TypeScript, Grunt, WebdriverIO, Express.js, Node.js, AngularJS, Angular, HTML, Django, REST APIs, Front-end, CSS, ECMAScript (ES6), Slack, Teamwork, HTML5
  • Full-stack Python Developer

    2018 - 2018
    S3: Shapiro Settlement Solutions (via Toptal)
    • Reimplemented data extraction from the Excel file into various microservice databases based on their new ETL workflow.
    • Updated the database models definition in Cloud Datastore, which is used in the new extraction flow.
    • Implemented the transformation of imported column data through the front-end UI in React.
    • Refactored the back-end APIs to preload entity and relationship options in Python.
    • Implemented the UI and back-end APIs for mapping relationships between entities imported from Excel files.
    Technologies: Flask, Storybook, GraphQL, Redux, React, Google Cloud Datastore, Google App Engine, Microservices, Python, Front-end, Slack, APIs, Teamwork
  • Front-end Web Developer

    2018 - 2018
    Megawarne Consulting (via Toptal)
    • Implemented a new UI layout with Ant Design components.
    • Refactored the authentication logic with redux-auth-wrapper.
    • Implemented the WebSocket communication between the back end and front end through MessagePack, a binary serialization format.
    • Executed showing the field-level validation error message from the back-end API response with redux-form and promise handling.
    • Tested and demonstrated React components using Storybook.
    • Introduced the HOCs for code reuse, logic, and Bootstrap abstraction.
    • Implemented the live detection view through the WebSocket subscription.
    Technologies: PostgreSQL, VirtualBox, Vagrant, Maven, Java, Storybook, Ant Design, React Redux Form, MessagePack, WebSockets, Redux, React, HTML, React Redux, Front-end, CSS, Redux Form, ECMAScript (ES6), Slack, CSS3, HTML5
  • Senior UI Developer

    2017 - 2017
    OpenRisk Technologies LLC (via Toptal)
    • Implemented Kafka topics UI into the React and Redux web app to handle real-time data feeds.
    • Created a multi-dimensional stocks chart with amCharts.
    • Implemented complex diagram visualization and interaction with Ogma.
    • Tested and demonstrated React components using Storybook.
    • Refactored the authentication logic with redux-auth-wrapper.
    • Utilized Immutable.js with PureComponent to boost the performance.
    Technologies: Apache Kafka, Storybook, Google Material Design, RxJS, Highcharts, AmCharts, Immutable.js, Redux-saga, Redux, React, HTML, React Redux, Front-end, CSS, Redux Thunk, ECMAScript (ES6), Koa, Sublime Text 3, Slack, CSS3, HTML5
  • Shopify Developer

    2016 - 2016
    Polysleep
    • Built an eCommerce platform with Shopify to sell mattresses for stress-free sleep.
    • Implemented the customer reviews section by building a custom plugin app.
    • Conducted the implementation of multi-language support in English and French with langify.
    Technologies: SCSS, Ruby, Shopify
  • Full-stack Developer

    2016 - 2016
    Mosaic Sustainability
    • Built a custom CMS to manage micro sites, pages, groups and users.
    • Developed RESTful APIs to connect tableau server and get response data.
    • Implemented the view of tableaus with user-specific settings.
    • Built front-end with Angular 2.
    Technologies: Tableau, GitHub, Angular, Ruby on Rails (RoR), Vue.js
  • Full-stack Web Developer

    2015 - 2016
    Theme Paradise
    • Worked on part-time engagement for the building of several responsive multi-purpose WordPress themes.
    • Built my WordPress theme framework called Crystal.
    • Utilized my strong experience with building WordPress shortcodes along with Visual Composer.
    Technologies: jQuery, JavaScript, WordPress, PHP
  • Web Developer

    2015 - 2016
    Nelou
    • Built a RESTful API for web and mobile app.
    • Developed cross-browser compliant front-end using AngularJS.
    • Tested front-end using Jasmine and back-end using Mocha.
    • Implemented an integration with Stripe for card payment processing.
    • Identified and corrected software deficiencies.
    Technologies: Git, Mocha, Bitbucket, Angular, Ruby on Rails (RoR)
  • Full-stack Web Developer

    2015 - 2015
    Charibin
    • Developed a fundraising auction system with Meteor.js.
    • Improved UI and UX with Bootstrap based on the mockup provided.
    • Revamped project setup and deployment with iron-cli and mupx.
    • Built a module to cache the backend API responses in the front-end to improve performance.
    • Conducted technical and functional research and analysis.
    Technologies: Google Places API, Iron CLI, Bootstrap, Stripe, Meteor
  • Web Developer

    2012 - 2014
    Manglobe, Inc.
    • Worked as a internal developer to maintain and upgrade the web app for their internal management system.
    • Scripted in Python and Shell for system administration and data processing.
    • Led a team of developers implementing business applications on top of the in-house developed RAD tool.
    • Designed and built a real-time chat module.
    • Implemented a continuous integration and deployment process.
    • Improved development and testing workflow with virtualization and container technologies.
    • Wrote image recognition engine using OpenCV C++.
    Technologies: C++, Python, Ruby on Rails (RoR)

Experience

  • Lithic
    https://privacy.com/

    I mostly worked on the front-end side of the mobile and web apps. I added new screens for the onboarding flow to the mobile app built with React Native.

    ROLE
    • Improved card details screen based on the new mockup.
    • Upgraded React Native and its dependencies version of the legacy mobile app to the latest ones.
    • Added new UI pages for onboarding flow to the web app built on MEAN stack
    • Improved the card details page based on the new mockup.

  • Mosaic Tableau Management

    - Built a custom CMS to manage microsites, pages, groups, and users.
    - Developed RESTful APIs to connect Tableau server and get response data.
    - Implemented the view of tableaus with user-specific settings.
    - Built front-end with Angular 2.

  • Nelou CMS

    - Developed a RESTful API for web and mobile apps.
    - Developed front-end using AngularJS.
    - Tested front-end using Jasmine and back-end using Mocha.
    - Implemented integration with Stripe for card payment processing.
    - Identified and corrected software deficiencies.

Skills

  • Languages

    CSS3, SQL, GraphQL, JavaScript, C++, C, Sass, HTML5, Python, PHP, ECMAScript (ES6), ES7, HTML, CSS, Java, TypeScript, Solidity, Ruby, SCSS, Pug
  • Frameworks

    CodeIgniter, Laravel, Redux, Angular, Django, React Native, Jest, Bootstrap, Django REST Framework, Koa, Express.js, Ruby on Rails (RoR), Electron, Next.js, Ant Design, Flask, AngularJS
  • Libraries/APIs

    REST APIs, Node.js, React Redux, Ramda, Lodash, Redux-saga, Redux Form, D3.js, jQuery, React, PayPal API, Immutable.js, Highcharts, RxJS, Stripe, Google Places API, React Redux Form, Formik, React Router, Mapbox GL, AWS Amplify, Moment.js, WebGL, Vue.js
  • Tools

    GitHub, Bitbucket, Redux Thunk, Webpack, Sublime Text 3, Git, Sublime Text, Atom, PyCharm, Mocha, Tableau, Maven, Vagrant, VirtualBox, WebdriverIO, Grunt, Metalsmith, Sentry, AWS SDK, Slack
  • Paradigms

    Object-oriented Programming (OOP), Functional Programming, REST, Test-driven Development (TDD), Continuous Integration (CI), Testing, Microservices, MEAN Stack, Search Engine Optimization (SEO)
  • Platforms

    WordPress, Shopify, iOS, Amazon Web Services (AWS), Ubuntu, Windows, MacOS, Blockchain, Ethereum, Docker, Apache Kafka, Meteor, Google App Engine, Firebase, Visual Studio Code
  • Storage

    MySQL, MongoDB, SQLite, PostgreSQL, Redis, Google Cloud Datastore
  • Other

    Freelance, SSH, Web Development, ECMAScript 6, AWS, APIs, Full-stack, Teamwork, Front-end, Bitcoin, Non-fungible Tokens (NFT), AmCharts, Google Material Design, Storybook, Iron CLI, WebSockets, MessagePack, Styled-components, OAuth, Server-side Rendering, Content Management Systems (CMS), Chatbots

Education

  • Bachelor's Degree in Computer Engineering
    2008 - 2012
    Tokyo University of Science - Tokyo, Japan

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