Andrej is available for hire

Andrej Gajdos

Verified Expert in Engineering

Full-stack Developer

Location

Prague, Czech Republic

Toptal Member Since

August 31, 2016

Andrej是一个专注于PERN/MERN栈的全栈开发人员，拥有超过10年的软件交付经验. As a fractional CTO and tech lead, Andrej管理过几个团队，为许多行业的全球客户交付软件, including healthcare, finance, and eCommerce. Thus far, Andrej已经为创业公司交付了20多个项目, digital agencies, 以及苹果和币安等财富500强公司.

Portfolio

Self-employed

JavaScript, React, Node.. js, MongoDB, PostgreSQL, MySQL，网站，开发...

GoSchoolBox

Node.js, Heroku, MongoDB, React，服务器端渲染(SSR)，优化...

Provenance

亚马逊网络服务(AWS)，亚马逊EC2, REST api，数据库，React, Node.js...

Experience

Front-end Development - 8 years Front-end Architecture - 8 years JavaScript - 8 years UI Development - 8 years Software Architecture - 6 years Node.js - 6 years React - 5 years Single-page Applications (SPA) - 3 years

Availability

Part-time

Preferred Environment

OS X, Visual Studio Code (VS Code)

The most amazing...

...我为苹果开发了一个像素完美的用户界面.

Work Experience

分数CTO，软件架构师，高级全栈开发人员

2017 - PRESENT

Self-employed

就产品开发路线图与公司进行战略咨询, developing workflow, setting project infrastructure, 架构和实现第三方集成, and providing code reviews.
Mentored senior developers with best practices, design patterns, 以及在可维护性和性能方面扩展web应用程序的工具.
重构和改进了代码库，为客户在未来的开发中节省了至少六位数的成本.
开发了一个交互式数据可视化，可以在地图上呈现数千个建筑物, 用户可以通过编辑多边形来编辑建筑物.

Technologies: JavaScript, React, Node.. js, MongoDB, PostgreSQL, MySQL，网站，开发, Front-end, APIs, CTO, Architecture, CSS, HTML, CSS3, HTML5, Next.js, Express.js, Tailwind CSS, D3.js, MobX, Responsive UI, UI Development, Single-page Applications (SPA), Web Development, Full-stack Development, Front-end Architecture, Front-end Development, Data Visualization, Storybook, Amazon Web Services (AWS), CircleCI, Contentful, Amazon EC2, Heroku, Technical Leadership, Solution Architecture, Full-stack, Minimum Viable Product (MVP), API Design, TypeScript, REST APIs, User Interface (UI), Figma, Software Engineering, Agile, SQL, Web Applications, Software Architecture, Interactive UI, Git, Responsive Design, GraphQL, Unit Testing, Dashboards, Databases, API Integration, User Experience (UX), MERN Stack, Leadership, Startups, Crypto

Software Architect

2022 - 2023

GoSchoolBox

优化平台和扩展基础设施，使用户从5万增长到100万.
解决了性能问题，用户流从10-15秒缩短到1秒.5 seconds.
改进了数据库搜索功能，允许用户在20秒内搜索数百万条记录.

Technologies: Node.js, Heroku, MongoDB, React，服务器端渲染(SSR)，优化, Datadog, Sentry, Amazon, MongoDB Atlas, MERN Stack, Apollo, GraphQL, Refactoring, Leadership, Webpack, TypeScript, Express.js

Fractional CTO

2022 - 2022

Provenance

就产品开发路线图提供战略咨询, 设定工程节奏以成功完成MVP.
Set up infrastructure and CI pipelines, 并进行代码审查，在问题转化为技术债务之前识别问题.
利用最佳实践和工具帮助开发人员加快开发过程并确保代码质量.

技术:亚马逊网络服务(AWS)、亚马逊EC2、REST api、数据库、React、Node.js, CTO, Architecture, Technical Leadership, Solution Architecture, Minimum Viable Product (MVP), Software Architecture, CI/CD Pipelines, Leadership, Startups, Express.js

React and Gatsby Developer

2018 - 2019

Nash

构建可定制的UI组件，用于多个项目. 搭建交易平台资金管理和支付系统.
纳什扩展，一个基于浏览器的加密货币钱包，和Chrome扩展.
用React、Gatsby和TypeScript构建公司网站.

Technologies: D3.js, TypeScript, Styled-components, GraphQL, Gatsby, React, JavaScript, Websites, Development, Front-end, HTML, CSS, UI Development, Front-end Architecture, Front-end Development, Single-page Applications (SPA), Storybook, Minimum Viable Product (MVP), User Interface (UI), Web Applications, Interactive UI, Unit Testing, Git, Dashboards, User Experience (UX), Startups, Crypto

React Developer

2018 - 2018

FastSwims

设计并搭建了一个组织游泳队和游泳比赛的赛事管理平台的功能原型.
根据客户的原型设计一个新的用户界面.
从头开始构建一个功能原型，作为一个单页应用程序.

Technologies: Redux-Saga, React, JavaScript, Front-end, CSS, HTML, Front-end Architecture, Front-end Development, Single-page Applications (SPA), Prototyping, Minimum Viable Product (MVP), User Interface (UI), Web Applications, Interactive UI, Dashboards

React Developer

2018 - 2018

Glofox

帮助交付一个用于管理健身工作室的React Native项目.
修复了React Native项目中的各种bug和问题.
针对Android平台优化了React Native项目.

技术:Redux, React Native, JavaScript，用户界面(UI)，初创公司

Principal Software Engineer

2017 - 2018

Saycaster

作为一名使用React和Node的全栈JavaScript开发人员.js.
设计并搭建互动播客平台. 播客可以上传音频文件，并在播客的特定时刻添加“亮点”, 可以是任何东西，从链接到社交媒体帖子, videos, or images.
用复杂的用户界面从头开始构建一个单页应用程序, including user interactions and animations.
设计并构建了项目架构和服务器.

技术:InVision, Twitter API, Babel, Webpack, SVG, D3.js, Redux, React, Knex.js, Objection.js, Koa, Node.js, JavaScript, PostgreSQL, Amazon S3 (AWS S3), Heroku, Development, APIs, Single-page Applications (SPA), Full-stack Development, Front-end Development, Front-end Architecture, CTO, Technical Leadership, Minimum Viable Product (MVP), Full-stack, Back-end, Back-end Development, HTML, CSS, API Design, REST APIs, User Interface (UI), Software Engineering, SQL, Web Applications, Software Architecture, Architecture, Interactive UI, Databases, API Integration, User Experience (UX)

Pre-sales Engineer

2016 - 2017

ZeroTurnaround

向来自世界各地的潜在客户展示和展示产品.
向开发团队演示产品特性，并展示如何在特定工作流的开发过程中使用它们, environment, and toolset.
通过在特定用例中展示我们的产品，帮助销售助理完成交易.
培训销售人员如何有效地向开发团队和经理展示和销售我们的工具.
Assisted customers with installation, troubleshooting, 和其他客户服务的配置问题.

技术:Java、咨询、IT咨询、销售、技术销售、技术咨询

Software Engineer

2015 - 2016

Ataccama

主要担任仪表板和数据可视化的前端开发人员.
实现用于数据质量管理的企业应用程序中的新特性和修复错误，并根据现代技术重写UI组件.
设计并实现了用于客户数据管理的交互式应用程序前端.
在GWT应用程序中设计并实现了服务器到服务器的通信和服务器推送.

技术:Errai、ActiveMQ、JMS、JSTL、Jakarta Server Pages (JSP)、D3.js, Babel, Gulp, Webpack, SCSS, Bootstrap, jQuery, Backbone.js, Immutable.js, Flux, React, Emacs, JavaScript, Java, APIs, HTML, CSS, User Interface (UI), REST APIs, Software Engineering, Web Applications

Data Visualization Developer

2013 - 2015

Techniserv, Taranzo

Analyzed, designed, 并实施了从社交网络和各种其他来源收集和处理结构化和非结构化数据的解决方案.
设计并实现了一个用于构建和可视化社交网络的模块.
从社交网络(如YouTube和Twitter)建立数据处理.

技术:JUNG, Twitter API, YouTube API, OrientDB, D3.js, Bootstrap, jQuery, JSTL, Jakarta Server Pages (JSP), Apache Maven, Spring MVC, Liferay, JavaScript, Java, APIs, Full-stack Development, Front-end Development, Software Architecture, Architecture, Back-end Development, Interactive UI, API Integration

Software Tester

2012 - 2013

Amberg Group

执行手动和自动测试并分析结果.
使用自动化测试开发和维护整个测试基础架构.
设计测试用例，编写文档，并报告问题.

技术:Ruby, Python, JavaScript, Ruby on Rails (RoR)， Selenium

Experience

Provenance

http://app.provenance.co/

作为一名副首席技术官，在产品开发路线图上为团队提供战略咨询. Managed and led a team of developers. 在问题转化为技术债务之前，我通过代码审查确定了问题, helped developers with best practices, 并且利用工具来加快开发过程并确保代码质量. 我还构建了项目的基础设施、CI管道和第三方集成.

GoSchoolBox

http://goschoolbox.com/

GoSchoolBox是一个SaaS平台，作为学区和辅导公司之间的技术基础设施层. 用户数量从5万增长到100万. GoSchoolBox平台遭遇了许多应用程序稳定性问题, such as spontaneous error messages, gateway timeout errors, and slow page load times. 作为一名软件架构师，我负责确保平台的稳定性、弹性和可伸缩性. 我帮助团队将APM与指标和性能仪表板集成和设置，以检测和诊断最终用户对关键任务服务的体验. 我重构和固定了关键的用户流，以提高用户流性能, server throughput, and page load performance. 我优化了MongoDB的搜索性能，使用户可以在几秒钟内搜索数百万条记录.

3icap

http://www.3imembers.com/

一个投资社区平台，供投资者发现交易和确定共同投资者. 该平台允许投资者彼此互动, keep track of deals, 为一群精心策划的私人投资者创建一个虚拟的投资俱乐部.

我设计并实现了与第三方服务的集成, such as DocuSign, Slack, and Stripe. 我还帮助团队建立项目工具，修复各种问题，并实现新功能.

Stackbit

http://app.stackbit.com

Stackbit是一个网站构建器，可以帮助任何级别的开发人员基于Next构建他们的Jamstack网站.js and Tailwind fast.

我帮助Stackbit的团队为主平台的设计系统设置工具和设计架构. 我协助并指导高级React开发人员使用最佳实践和模式来解决React项目中的复杂流程. 我修复了平台中的各种问题和错误，以及针对企业客户的附加功能集.

Getctrl

http://www.getctrl.co/

Getctrl是客户成功专业人士的客户数据平台. 它使售后人员能够从不同的应用程序中获取数据来创建工作空间.

作为前端开发人员，我开发了新功能并修复了现有的代码库. 我还帮助和指导高级React开发人员的最佳实践.

Nash.io

http://nash.io/

一个用React、Gatsby、TypeScript和样式组件构建的快速静态网站. 所有页面都是完全响应和优化移动观看.

我从零开始建立了这个公司网站，添加和重用了Storybook中的现有组件.

Cryptocurrency Exchange Platform

http://app.nash.io/

A cryptocurrency exchange platform.

作为React开发人员加入项目并实现设计系统, portfolio management, and payment systems. 我使用了React、TypeScript、Storybook和GraphQL.

Archipelago

http://archipelago.art/

Archipelago是下一代NFT市场，提供精心策划的生成艺术NFT. As a front-end consultant, 我帮助团队审查现有的代码库, refactor problematic flows, and fix various bugs and issues.

Security Tokens Offering Platform

A secure, customer-centric, 分散的在线证券交易市场允许各级投资者买卖数字证券. 客户是一家领先的加密货币交易所. I worked as a senior front-end engineer. 担任前端实现架构师，审核其他前端开发人员的代码.

System Master Planner

为总体规划者、能源和资源管理者以及政策制定者提供的计算工具. 它允许用户评估大型建筑和其他资产的可持续性和弹性方案.

我做过React开发人员，开发过交互式数据可视化, 在LeafletJS地图上以多边形的形式渲染数以千计的建筑物.

FastSwims

http://www.fastswims.com/

一个项目管理平台，用于管理游泳队和游泳比赛. 我根据客户的原型设计了一个新的用户界面，并构建了一个功能原型.

开发工具:JavaScript, React和Redux-Saga.

Saycaster Rebranded to Bitcast

互动播客平台，具有以下特点:
•播客可以上传他们的音频，并添加5-20个点到他们的播客.
•这些点可以是任何东西，从社交媒体帖子的链接到其他视频或图像.
•听众可以对这些特定的地点进行倾听和评论.

SushiSwap Migrator

http://sushi-migrator.vercel.app/

A Web3.在这个项目中，用户可以将LP位置从Uniswap迁移到SushiSwap. 用户可以通过MetaMask与以太坊区块链进行交互, view the ERC-20 tokens list and LP positions, and add new ERC-20 tokens.

Vertigo

A project for a company in the marine industry. 我曾作为数据可视化专家构建Neo4j图形数据库的交互式可视化. I developed this visualization in React, D3.js, and Storybook.

Potentials

我用React为这个电子商务工具构建了用户界面. 它帮助CEO和销售助理维护和处理潜在客户的详细信息. 我使用React和Tailwind构建了用户界面.

Notion API Connector

http://notionapiconnector.com/

我建立了这个谷歌Chrome扩展连接和导入数据从任何API到概念.

CHROME WEB STORE LISTING http://chrome.google.com/webstore/detail/notion-api-connector/bafkcebllidammdngjlpcgnoodkappdg

SalesforceToNotion

http://salesforcetonotion.com/

一个Chrome浏览器扩展，集成了Salesforce和Notion之间的数据. 它允许用户将Salesforce数据直接拉入Notion工作区.

CHROME WEB STORE LISTING
http://chrome.google.com/webstore/detail/salesforcetonotion/dlebnfljbolfokomdlcdddgdopiaekeg

Filipi

Filipi是一家与Next合作的家具电子商务商店.js, Node.js, and MySQL. 我帮助业主将整个解决方案迁移到另一台服务器上, fix various issues and bugs in SEO, manage data, and set up analytics tools.

Tauchain

Created a Node.js后端服务，处理来自第三方api(如第三方交换)的数据, GitHub API, Twitter API, and Telegram API. The server is deployed on AWS. 我在之前的开发人员之后帮助客户修复了项目，替换了无头CMS解决方案.

Software Development Blog

http://andrejgajdos.com/blog

My freelance software development blog. It was built with WordPress and JavaScript. 我的博客是关于JavaScript、React、Node开发的技巧、教程和技术解决方案.js, and related technologies.

Ivana Neckarova

http://ivananeckarova.com/

A personal WordPress website, 我对模板进行了定制，以实现针对移动设备的独特设计和响应. 我设置了WordPress插件，以提高网站性能和搜索引擎优化.

Link Preview Generator

http://www.npmjs.com/package/link-preview-generator

获取URL的预览数据(标题、描述、图像和域名). I built this Node.使用Puppeteer无头浏览器来抓取网站并获得网站的标题, description, image, and others.

Neo Transfer

http://github.com/AndrejGajdos/neo-transfer

Neo Transfer允许您使用私钥登录, see balance, and transfer NEO or GAS within Testnet. 该项目基于NEO区块链的JavaScript SDK. The front end is implemented in React.

Newsfeed Cryptogoods

http://github.com/AndrejGajdos/newsfeed-cryptogoods

Newsfeed for events on crypto goods. A single, responsive page for the newsfeed. 轮询每15秒发生一次，以实时更新新闻提要中的新事件. 这个前端项目是使用JavaScript、React、Redux、Redux- saga和Twitter Bootstrap构建的.

Authenticating Users in SPA using Node.js, Passport.js, React, and Redux

http://github.com/AndrejGajdos/auth-flow-spa-node-react

使用Node的单页应用程序中的用户身份验证.. js、React、Redux和Koa结合Passport.

http://andrejgajdos.com/authenticating-users-in-single-page-applications-using-node-passport-react-and-redux/

Development tools: JavaScript, Node.js, React, Redux, Passport.js.

Nested Datatables

http://andrejgajdos.github.io/nested-datatables/

jQuery DataTables插件，用于呈现嵌套的数据表. 内部表独立于外部表的数据和布局. 我为一个数据管理产品创建了这个插件.

Development tools: JavaScript and jQuery.

ES6、React、Sass和Bootstrap的Webpack安装

http://github.com/AndrejGajdos/webpack-react

Webpack配置来捆绑ES6、React、Sass和Bootstrap用于生产和开发.

http://andrejgajdos.com/setting-up-webpack-for-es6-react-sass-and-bootstrap/

开发工具:JavaScript、React和Webpack.

Social Graph

将社交网络可视化为有向多图的portlet. Jung库用于构建multigraph, multigraph存储在OrientDB中. 可视化和其他组件是在D3中构建的.js and Bootstrap.

开发工具:Java, JavaScript, Liferay, JSP, Jung, OrientDB, D3.js, Bootstrap

Sample Source Code

此源代码是客户数据管理应用程序的前端. 除了登录页面之外，我开发了所有内容，并使用了ES6 (Babel)等技术。, React, Immutable.js, Bootstrap table, and webpack.

Instructions:

• Install Node.js from nodejs.org/en/download/.
• Install Bower from bower.io/#install-bower.
•进入终端的项目根目录，安装其他依赖项i.e., npm install and Bower install.
• Follow npm run start.
• Open the URL localhost:8080/ and type in:
a) User: andrej
b) Password: nachos

SVG Sprite into PNG

http://github.com/AndrejGajdos/svg-sprite-to-png

使用Gulp将SVG精灵转换为PNG图像的工作流.

http://andrejgajdos.com/how-to-convert-svg-sprite-into-png-images/

Development tools: JavaScript, Gulp

Server Push in GWT Application with Errai

http://github.com/AndrejGajdos/gwt-errai-messaging

使用Errai框架在GWT应用程序中实现从服务器到客户机的服务器推送消息.

http://andrejgajdos.com/first-steps-with-gwt-and-errai-messaging/

Development tools: Java, GWT, Errai

Contract Generator Tool

一些保险经纪人有一个XLS格式的保险和客户列表，需要根据DOC和DOCx格式的合同模板生成各种合同. 用户可以设置数据库(XLS或XLSx)和所需的列, which will be parsed into the contract. 该应用程序在SQLite中有一个保险数据库. 主窗口包含带有详细信息的客户端列表, where the user can instantly search clients, add required information (date, overpayment, insurance from database), choose contract templates, 并为客户端生成合同(DOC或DOCx). The UI is built in WPF and ADO.NET用于解析来自Microsoft Excel文件的数据.

Development tools: C#/.NET, WPF, SQLite, ADO.NET

Personal Calendar

http://github.com/AndrejGajdos/personal-calendar

具有两种视图模式(周/月)的基本个人日历应用程序. 该应用程序生成日志文件并使用MySQL数据库. 表示层是用Swing和SwingWorker构建的. 到数据库的连接是用JDBC开发的. 该项目包含简单的JSP页面，用于查看事件列表及其详细信息.

开发工具:Java, JSP, Swing, SwingWorker, MySQL, JDBC

Education

2013 - 2015

服务科学、管理和工程专业硕士学位

Masaryk University Brno - Brno

2014 - 2014

伊拉斯谟交换生信息学创新与研究硕士

加泰罗尼亚理工大学-巴塞罗那

2009 - 2013

Bachelor's Degree in Applied Informatics

Masaryk University - Brno

Skills

Libraries/APIs

Underscore.js, React, Node.. js, React Router, REST api, Atomic CSS, Passport.js, jQuery Plugins, jQuery UI, Redux-Saga, D3.js, Immutable.js, JSTL, Chai, jQuery, JavaScript Charting, AWS Amplify, GitHub API, Twitter API, YouTube API, Objection.js, JDBC, Backbone.js, OpenGL, Win32 API, Windows Forms (WinForms)， JMS，传单，MobX, Web3.. js, Stripe, Stripe API, Puppeteer, Slack API, Salesforce API

Tools

Git, Redux Thunk, Webpack, Gulp, Bower, Mocha, Emacs, PostCSS, Knex.js, Babel, GitLab, GitHub Pages, GitHub, Trello, InVision, ActiveMQ, Apache Maven, CircleCI, Figma, LaunchDarkly, Slack, Notion, Sentry, MongoDB Atlas, NPM

Frameworks

Express.js, Redux, Next.js, Koa, Bootstrap, Spring MVC, Flux, JUnit, Tailwind CSS, Material UI, Errai, React Native, Ruby on Rails (RoR), Jakarta Server Pages (JSP), Swing, Windows Presentation Foundation (WPF), .NET, Jest, Cypress, Selenium

Languages

JavaScript 6, CSS, HTML, CSS3, HTML5, JavaScript, TypeScript, Object-oriented JavaScript (OOJS), Java, Less, SCSS, Sass, ECMAScript (ES6), SQL, GraphQL, C, Python, Ruby, PHP, C#, UML, C++

Paradigms

Model View Controller (MVC), Unit Testing, Object-relational Mapping (ORM), Agile Software Development, Functional Programming, REST, Object-oriented Programming (OOP), Object-oriented Design (OOD), Software Testing, Automated Testing, Search Engine Optimization (SEO), Requirements Analysis, Web Architecture, Responsive Layout, Agile, Refactoring

Storage

JSON, PostgreSQL, Amazon S3 (AWS S3), Graph Databases, SQLite, MySQL, OrientDB, MongoDB, Relational Databases, Databases, Datadog, Cloud Firestore

Platforms

Firebase, Java EE, WordPress, Contentful, Amazon Lightsail, AWS Lambda, Amazon Web Services (AWS), OS X, Heroku, Amazon, MacOS, Windows, Linux, Blockchain, Twitter, Amazon EC2, Web, Mapbox, Visual Studio Code (VS Code), Salesforce, Vercel

Other

Responsive UI, UI Development, Ajax, Front-end, Single-page Applications (SPA), Web Development, Full-stack, Front-end Development, Front-end Architecture, Websites, Development, React Hooks, Web App Development, Minimum Viable Product (MVP), User Interface (UI), Atomic Design, Software Engineering, Web Applications, Interactive UI, Dashboards, UI Components, UI Libraries, Component Libraries, API Integration, APIs, Back-end, ESLint, Technical Consulting, Back-end Development, Writing & Editing, Data Visualization, Presentations, Sales, Customer Service, Consulting, Programming, Software Design, Styled-components, Gatsby, CTO, Architecture, Software Architecture, Full-stack Development, Solution Architecture, Slate.js, Responsive Design, Apollo, User Experience (UX), MERN Stack, Leadership, Startups, Cloudflare, Prismic, Webhooks, Storybook, JUNG, SVG, Web Scraping, Social Networks Development, Data Analysis, Liferay, BPM, Messaging Patterns, Sales Presentations, Chrome Extensions, Ethers.js, Scraping, Prototyping, Technical Leadership, IT Consulting, Tech Sales, CSS-in-JS, Technology Consulting, Team Leadership, Local SEO, API Design, eCommerce, Strapi, Solution Design, APM, Performance, Server-side Rendering (SSR), UI Testing, CI/CD Pipelines, Optimization, Crypto, Non-fungible Tokens (NFT), SaaS

Collaboration That Works

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与你选择的人才一起工作，试用最多两周. Pay only if you decide to hire them.

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