Jack is available for hire
Hire JackJack Penny
Verified Expert in Engineering
Full-stack Developer
Cheltenham, United Kingdom
Toptal member since January 20, 2022
Bio
Jack is a full-stack developer specializing in JavaScript, React, Perl, and PostgreSQL who has been working professionally as a freelance developer for over 10 years. Most of his back-end work has been related to legacy systems based on in-house frameworks. For the past four years, Jack has moved on to newer technologies such as React and GraphQL, first with an education startup and, more recently, building an entire eCommerce platform from scratch.
Portfolio
simpleFLOORS
Perl, Node.js, React, PostgreSQL, GraphQL, Bootstrap, Adobe Photoshop, HTML...
GoTutor
MongoDB, Node.js, React Native, Adobe Photoshop, React, SQL, APIs
GamerNorth
PHP, HTML, CSS, Linux, Python, SQL, Minecraft World
Experience
- JavaScript - 16 years
- Linux - 14 years
- Adobe Photoshop - 10 years
- Node.js - 10 years
- eCommerce - 10 years
- PostgreSQL - 9 years
- Perl - 9 years
- React - 5 years
Preferred Environment
Linux, JavaScript, React, Vim Text Editor
The most amazing...
...open source project I've created is a lexer parser transpiler, which can be used for templating systems and front-end frameworks.
Work Experience
Full-stack Developer
2013 - 2020
simpleFLOORS
- Worked with an extensive custom-made Perl and PostgreSQL back end, creating business logic for the client, fixing problems, and providing emergency support.
- Upgraded the old Perl 5.10/Apache, 1.3/Postgres 9 system to the latest software despite the significant upgrades needed to the codebase.
- Utilized Magento to work on the front end while fixing bugs.
- Created an eCommerce solution from scratch using React and Node.js, interfacing the ERP and a custom in-memory database solution to improve the performance—the client was previously using Magento, which was very slow.
Technologies: Perl, Node.js, React, PostgreSQL, GraphQL, Bootstrap, Adobe Photoshop, HTML, Enterprise Resource Planning (ERP), eCommerce, Payment APIs, Shipping Management, TypeScript, Python, SQL, APIs, Moose
Founder
2018 - 2019
GoTutor
- Founded a startup to introduce students to tutors in Hong Kong. This project lasted one year.
- Wrote a framework from scratch to handle the back end.
- Created a mobile app for the service using React Native, based on a design created in Photoshop.
- Delegated the front end development, bug fixing, unit testing to the other two team members, and security auditing to a temporary contractor.
Technologies: MongoDB, Node.js, React Native, Adobe Photoshop, React, SQL, APIs
Full-stack Developer
2011 - 2012
GamerNorth
- Developed a dashboard that allows players to modify their in-game Minecraft characters from a web portal—possibly the first of its kind.
- Maintained a Linux-based server dealing with emergencies.
- Optimized a large Minecraft server—the largest at the time—that was running on a slow Java-based back end. Implemented a RAMDisk with live swapping for maximum efficiency, among other features.
Technologies: PHP, HTML, CSS, Linux, Python, SQL, Minecraft World
Co-founder
2010 - 2011
Zizziz Ltd
- Co-founded a small company with a friend while still in high school to build and sell computers using an eCommerce website.
- Designed and wrote the eCommerce website from scratch using PHP, with support for PayPal payments and a "design-a-computer" feature for customized orders.
- Built custom-made PCs, some of them including advanced technologies such as liquid cooling.
Technologies: PHP, Adobe Photoshop, eCommerce, PayPal API, SQL
Experience
Drumkraft
DrumKraft is a project that allows people to create high-quality drum samples in a browser. Using signal processing and physical modeling, surprisingly realistic drum sounds can be created and smashed together using the built-in drum machine. Samples can then be exported in wav, sfz, or sf2 formats.
Curls: Mustache-inspired Templating System with Support for Logical Statements
https://curls.stextended.com/Curls is a templating system I wrote for my static site generator. Inspired by Mustache for its simplicity, I made it a transpiler to support logical statements, like "if" and "while", which are not supported in Mustache. The project showcases my ability to write lexers and parsers.
STExtended: A Static Site Generator
https://stextended.comSTExtended is a static site generator somewhat inspired by the likes of Jekyll. It supports macros, templating, and classless HTML and is ideal for people who want to write blogs. I used this piece of software to power most of my personal websites.
COVID-19 Case Count API
https://github.com/modamodamoda/covid19-apiCreated, for educational purposes, a COVID-19 case count API that scrapes data from the Worldometer and the John Hopkins University GitHub repository to create an API server for querying case count details. The endpoints support case-count by country, by time, and more.
TypeScript Node.js HTTP Server/Router
https://github.com/modamodamoda/ts-serverI built a TypeScript HTTP server/router for Node.js that partially supports express middlewares. It also supports controllers, decorators, and router trees. Additionally, there is a fast hashmap-based router feature for people using many static routes.
Skills
Libraries/APIs
Node.js, React, Mustache, PayPal API
Tools
Adobe Photoshop, Vim Text Editor, Jekyll, GitHub
Languages
Perl, JavaScript, HTML, PHP, CSS, SQL, Sass, Python, GraphQL, TypeScript
Storage
PostgreSQL, MongoDB
Platforms
Linux, Moose
Frameworks
Bootstrap, React Native, Express.js
Other
Enterprise Resource Planning (ERP), eCommerce, APIs, Payment APIs, Shipping Management, HTTP, Minecraft World, Signal Processing, Digital Signal Processing
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