Jan Kelin, Developer in Prague, Czech Republic
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Jan Kelin

Verified Expert  in Engineering

Full-stack Developer

Prague, Czech Republic

Toptal member since July 22, 2022

Expertise
JavaScriptReact.jsTypeScriptNode.jsPostgreSQLDockerGraphQLC#OAuthFront-endElasticsearchAngularJS
Bio

Jan has worked on web development professionally and as a hobby for more than six years. He primarily focuses on full-stack development, but he also has a wide range of experience with other parts of the software pipeline, including systems analysis, architecture, team leadership, DevOps, and dockerizing.

Portfolio

DNAi
TypeScript, Node.js, JavaScript
Applifting
React, TypeScript, OAuth 2, GraphQL, REST, PostgreSQL, Elasticsearch, OpenAPI...
VitSoft
JavaScript, TypeScript, AngularJS, C#

Experience

  • JavaScript - 7 years
  • TypeScript - 6 years
  • React - 6 years
  • Docker - 5 years
  • Node.js - 5 years
  • PostgreSQL - 5 years
  • C# - 4 years
  • GraphQL - 4 years

Availability

Part-time

Preferred Environment

Visual Studio Code (VS Code)

The most amazing...

...project I've worked on is the BankID developer portal which interconnects all major Czech banks. I've conducted a systems analysis and led the team.

Work Experience

Front-end Tech Lead

2022 - 2022
DNAi
  • Managed and worked with the front-end team. Most of the work involved getting the team up to speed with modern coding practices like code reviews, CI/CD, and code quality assurance.
  • Pushed a redesign initiative with an external agency to help re-work the application from the demo mode into production mode.
  • Assisted in setting up GitLab CI/CD and Keycloak OpenID Connect provider.
Technologies: TypeScript, Node.js, JavaScript

Front-end Engineer | Systems Analyst | Team Lead

2017 - 2021
Applifting
  • Built an API product at developer.bankid.cz that interconnects all major Czech banks. I was a systems analyst and team lead.
  • Worked as a front-end lead on several projects in Agile teams.
  • Provided front-end expertise and mentoring across the organization.
Technologies: React, TypeScript, OAuth 2, GraphQL, REST, PostgreSQL, Elasticsearch, OpenAPI, Node.js, JavaScript, Heroku

Full-stack Developer

2016 - 2017
VitSoft
  • Migrated an old application for tracking time and projects from AngularJS to React and old ASP.NET on the back end to ASP.NET Core.
  • Worked on an application for hospital management for a US client with an international team.
  • Helped with the screening and onboarding process for new candidates.
Technologies: JavaScript, TypeScript, AngularJS, C#

Experience

Czech BankID

https://developer.bankid.cz/
A Czech BankID solution that interconnects all major Czech banks. This developer portal includes extensive public API documentation, API and credential management, a back-office management section, and tooling for bank developers that integrate with BankID.

I have designed an API for its core API product modeled after OpenID Connect (OIDC) specification, participated in the OIDC eKYC IDA working group, worked on the systems analysis for the BankID solution, and led one of the teams implementing it.

Signull

A tool for crypto traders that allows users to quickly screen obscure and new crypto tokens. It has a feature that enables one to view dozens of charts at once, quickly scan different timeframes, and set custom alerts for new and exciting tokens. I have led the front-end team and helped with systems analysis.

Erste Developer Portal

A developer portal for a major European bank group. It includes documentation, API and authentication management, a back office, and a custom-built CMS. I have led the front-end team from the inception of the project and helped with a custom GraphQL orchestrator we built.

Skills

Libraries/APIs

React, Node.js, OpenAPI

Tools

GitLab CI/CD

Languages

TypeScript, JavaScript, GraphQL, C#

Frameworks

OAuth 2, .NET, ASP.NET, AngularJS

Paradigms

REST, DevOps

Platforms

Docker, Heroku

Storage

PostgreSQL, Elasticsearch, Redis

Other

Systems Analysis, SQL Server 2015, User Experience (UX), Front-end, OpenID Connect (OIDC), TimescaleDB

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