Jiří Straka, Developer in Prague, Czech Republic
Jiří is available for hire
Hire Jiří

Jiří Straka

Verified Expert  in Engineering

Software Developer

Prague, Czech Republic
Toptal Member Since
June 6, 2016

Jiří is a full-stack .NET developer with more than eight years of experience in development and three in the banking industry. He has built highly sought-out web apps using the latest Microsoft technologies and client-side frameworks such as React and Angular 2+ to create dynamic and responsive UIs. Jiří also has significant experience with service-oriented architecture, complex problems in large systems, performance issues, and much more.


Mosaic Digital Systems, Inc.
Angular, Amazon Web Services (AWS), AWS Lambda, JavaScript, Python, MySQL...
Advertise Purple, Inc
Angular, Node.js, Amazon Web Services (AWS), JavaScript, Python, MySQL...
E4 Logics
Angular, CSS, HTML5, PrimeNG, NGXS, Bootstrap, JSON, REST, Front-end, Full-stack




Preferred Environment

Git, Visual Studio Code (VS Code), Azure Data Studio, Microsoft SQL Server, Postman, Swagger, DevOps, JetBrains Rider, DataGrip, Visual Studio

The most amazing...

...project I've designed and implemented was a tool that automatically searched phone numbers from the internet to reduce the time needed for operators.

Work Experience

Full-stack Developer

2023 - PRESENT
Mosaic Digital Systems, Inc.
  • Developed a new greenfield business intelligence platform based on the provided application designs in three months. Maintained the application with new business requirements.
  • Used NGXS, one of the latest Angular state management libraries, to handle global application state rights.
  • Created reusable, generic components based on the Angular Bootstrap library, such as grids, grid filters, charts, widgets, etc.
  • Implemented new API endpoints for the front end using Node.js and the Sequelize library.
  • Coded mobile-first HTML email templates based on provided designs. Optimized them for a large number of email clients.
  • Integrated a small team of five developers using the Scrum methodology with daily standup meetings.
  • Tracked and fixed bugs using Jira as a tracking tool.
Technologies: Angular, Amazon Web Services (AWS), AWS Lambda, JavaScript, Python, MySQL, Elasticsearch, Node.js, TypeScript, Bootstrap, NGXS, Application State Management, SQL, PostgreSQL, Sequelize, Express.js, Koa, HTML, HTML5, CSS, Flexbox, Scrum, Kanban, Agile, Web Development, REST, APIs, Unit Testing, Integration Testing, Integration, Full-stack

Full-stack Developer

2021 - 2023
Advertise Purple, Inc
  • Integrated the platform with various data sources, allowing us to view and analyze key performance indicators about marketing efforts, including sales, clicks, affiliates, and conversions.
  • Created reusable, generic components based on the Angular Bootstrap library, such as grids, grid filters, charts, widgets, etc.
  • Implemented new API endpoints for the front end using Node.js and the Sequelize library.
  • Tracked and fixed bugs using Jira as a tracking tool.
  • Integrated a small team of five developers using the Scrum methodology with daily standup meetings.
Technologies: Angular, Node.js, Amazon Web Services (AWS), JavaScript, Python, MySQL, AWS Lambda, Elasticsearch, Angular Material, Bootstrap, NGXS, Redux, CoreUI, Stripe, Stripe API, Stripe Payments, Sequelize, SQL, Databases, PostgreSQL, APIs, Full-stack Development, Full-stack, Architecture, Email Marketing, HTML, TypeScript, Jira, Agile, Scrum, Kanban, Unit Testing, Integration Testing, Integration

Angular Developer

2021 - 2021
E4 Logics
  • Implemented phase two of an online finance application for budget management according to the application designs in InVision and Jira tickets.
  • Applied advanced custom application components based on the PrimeNG component library.
  • Consumed heavy JSON-oriented back-end REST API services.
  • Used an NGXS library for client-side state management.
Technologies: Angular, CSS, HTML5, PrimeNG, NGXS, Bootstrap, JSON, REST, Front-end, Full-stack

Senior Full-stack Developer

2020 - 2021
Saasman Solutions, Inc.
  • Developed and designed the whole back-end architecture from scratch to use the latest standards, patterns, and principles.
  • Implemented custom-branded reusable Angular components based on Angular Material for the client's application, such as grid, dropdown, rich text editor, and more.
  • Worked on all application parts, such as designing the database schema, exposing a REST API using ASP.NET Core, and implementing Angular front-end feature modules.
  • Integrated the Stripe payment method for purchases and user subscription handling.
Technologies: Angular, C#, Entity Framework Core, ASP.NET Core, Angular Material, SQL, Sass, TypeScript, SignalR, REST, NGXS, Stripe API, Architecture, CQRS, Web Development, Back-end, Front-end, Full-stack Development, Databases, Azure, User Interface (UI), User Experience (UX), Email Marketing, Web Security, JSON Web Tokens (JWT), Integration, APIs, Full-stack

Freelance Web Application Engineer

2019 - 2020
  • Implemented a custom component library, including components such as DropDown, Typeahead, Popover, Tooltip, and more.
  • Worked as a part of a small agile scrum team with standups, sprint reviews, and retrospective meetings.
  • Developed the company's custom npm packages, including reusable code, custom user components, data services, shared business logic, and more.
  • Implemented the new application features according to Zeplin mockups.
  • Wrote front-end unit tests and automated E2E Cypress tests.
Technologies: Cypress, NPM, SCSS, RxJS, NGXS, Angular Material, Angular, Storybook, Integration, APIs, Full-stack

Freelance .NET Full-stack Developer

2018 - 2018
Gulf Coast Solutions
  • Enacted several new screens and many new features into the application according to specification.
  • Implemented user and role management supporting user CRUD operations and assigning users various types of roles.
  • Designed and implemented a data caching layer for better application performance.
  • Applied Data Explorer to configure SQL queries dynamically in the database, display the results in the data grid, and export the outcome into various data formats such as Excel, PDF, and the like.
  • Visualized data using jQuery DataTables featuring partial inline editing, modal dialog editing, input validation, and more.
Technologies: SQL Server 2016, Microsoft SQL Server, Bootstrap, jQuery DataTables, jQuery, JavaScript, C#, .NET, ASP.NET, APIs, Full-stack

Freelance Full-stack .NET Developer

2017 - 2018
Anguleris Technologies
  • Implemented new features into the Angular 2 front-end part of the application.
  • Optimized long-running Entity Framework queries into pure T-SQL stored procedures to run as fast as possible.
  • Helped other developers to optimize Entity Framework database queries.
  • Fixed various bugs for both the front and back end from the product's backlog.
Technologies: C#, Azure, Microsoft SQL Server, Entity Framework, T-SQL (Transact-SQL), TypeScript, Angular, ASP.NET, Integration, Full-stack

Freelance ASP.NET Web Developer

2017 - 2017
  • Implemented a full-stack, multitenant web app in Azure. It’s a distributed system that gathers application performance information for our enterprise customers and is aggregated in a centralized database.
  • Built development-and-production Azure environments and set up the Visual Studio Team Services' continuous integration.
  • Designed the whole web application's back-end and front-end parts.
  • Developed a whole application as a greenfield project from screen mockups.
  • Implemented several application screens such as user management, account management, chart dashboard, and more.
  • Implemented the whole application as a single-page application using Angular 2 and Webpack.
Technologies: C#, Chart.js, Bootstrap, Webpack, Angular, TypeScript, Azure, Entity Framework Core, ASP.NET Identity, ASP.NET Core, Integration, Full-stack

Freelance .NET Engineer

2016 - 2017
Procore Technologies
  • Developed an intranet administration portal for a synchronization job between a relational database and a REST API.
  • Built the administration portal pages, including editing job parameters, toggling modules to synchronize, displaying application logs, authentication of jobs using the client's REST API, and more.
  • Implemented part of the synchronization job itself—consisting of a two-way synchronization between a relational database and a REST endpoint.
  • Carried out the directive where an emphasis was placed on making everything as asynchronous as possible.
  • Used the latest technologies, such as ASP.NET Core and EF Core, in building a lightweight, self-contained intranet application.
Technologies: C#, Windows PowerShell, JSON, jQuery, Bootstrap, Entity Framework Core, ASP.NET Core, Integration, Full-stack

Freelance Full-stack Developer

2016 - 2016
CSR Limited
  • Implemented new web portal pages according to the client's specifications.
  • Created new web API services to be consumed by the AngularJS client code.
  • Wrote various kinds of analytical SQL queries required by the client.
  • Investigated and fixed different kinds of defects.
Technologies: C#, Entity, Agile, Slack, Microsoft SQL Server, Bootstrap, AngularJS, Web API, ASP.NET, Full-stack

Freelance Senior .NET Engineer

2016 - 2016
R2L Consulting (via Toptal)
  • Extracted relevant data from multiple MS SQL Server databases with different schema into a generic table schema—data transformation.
  • Wrote SQL queries to load all relevant data from source databases.
  • Implemented a data importer tool with a great emphasis placed on performance and reusability.
Technologies: Design Patterns, Json.NET, Dapper, Entity Framework, SQL, .NET, C#, Full-stack

Senior .NET Developer

2014 - 2016
Commerzbank AG
  • Worked on two internal projects: one of them was a greenfield project for trading and the second was a CRM for financial institutions.
  • Implemented database scripts, services, user interfaces, and business logic.
  • Developed highly complex and configurable client-side validation components.
  • Created components for synchronization of files between file servers.
  • Worked as part of the cross-country development team (Czech Republic, Germany, and the UK).
  • Designed and developed a printing module using iTextSharp.
Technologies: C#, Infragistics, Microsoft SQL Server, Log4Net, Entity Framework, ASP.NET MVC 5, jQuery, Moq, iTextSharp, PostSharp, NUnit, Dapper, Ninject, DI, AngularJS, TypeScript, SignalR, Web API 2, .NET, APIs, Full-stack

.NET Developer

2013 - 2014
Softec s.r.o.
  • Worked on several projects in the banking industry.
  • Developed an application for the automatic searching of contact information on behalf of clients.
  • Built a module for generating print outputs in RTF and PDF.
  • Implemented a document management system for one of the largest banks in the Czech Republic.
  • Implemented a configurable automatic notification module.
  • Presented new features of HTML5 and CSS3 for the rest of the development team.
Technologies: jQuery, Kendo UI, Unity, Knockout (Knockout.js), Entity Framework, SQL, DI, ASP.NET Web API, ASP.NET MVC, C#, Email Parsing, Web Scraping, Document Parsing, PDF, APIs, Full-stack

.NET Developer

2012 - 2013
Dotnetic s.r.o.
  • Took part in all the project phases such as requirements gathering, analysis, development, testing, and deployment.
  • Developed an intranet web application for the salesmen.
  • Designed the application architecture and a communication interface between a tabled salesman application and our intranet application.
  • Programmed synchronization jobs for the accounting system.
  • Exposed the web services (WCF) for a client's WPF application that was made for use by the salesmen.
Technologies: C#, Microsoft SQL Server, ASP.NET, Telerik WPF, Windows Presentation Foundation (WPF), Entity Framework, jQuery, ASP.NET Web Forms

.NET Developer

2010 - 2012
Absolute Audio s.r.o.
  • Developed internal applications, company web pages, and an e-shop.
  • Maintained and supported applications.
Technologies: C#, Telerik, Entity Framework, SQL, ASP.NET Web Forms

Junior .NET Developer

2009 - 2009
Sitronics Telecom Solutions
  • Developed a data access layer.
  • Transformed flat database data to hierarchical data structures (e.g., trees).
  • Wrote unit tests.
Technologies: C#


The Aurora is a highly complex and configurable software system able to calculate correct P&L results by using independent market data, provide efficient analysis tools, and use a comprehensive reporting and agreement process. The process data feeds from trading systems like Summit, Murex, and more.

I worked as part of one of two scrum teams; each team had six to seven members.


RMS stands for Relationship Management System, used as a CRM for financial institutions. RMS is one of the oldest projects running in Commerzbank. It has been developed since 2006. I was part of a team with ten people (developers, a team leader, testers, and more). The methodology used for development was Scrum with daily stand-up meetings.

It consisted of several modules:
• Bank: bank core information.
• Client profile: external systems adjusted data consisting of revenues, costs, and operational risks.
• Customer due diligence: from bank compliance management to ratings.
• Client interaction: prepared everything from customer interaction to summaries.
• Documents: customer document handling.
• Reporting: various reports, including configurable select from RMS.
• Trade risk distribution: syndicate loan handling.

CSPS Application

The application is used to search contact information (addresses, phone numbers, and more) to bank’s clients from public sources from pages like telefonni.zoznam.sk, google.com, 1188.seznam.cz, and others.

Its emphasis was on modularity, extensibility, and configurability. I implemented the whole CSPS within three months, including the functional design and implementation.

CAFE Application

The project's goal is to optimize the process of creating and approving credit proposals of corporate clients, which also includes the optimization of the process of risk assessment and credit approval.

CML Application

The application's purpose was to support loading the data from the accounting system, manage orders from client salespeople applications, and write new orders into the accounting system. The salespeople have the client application written in WPF for placing orders in a CML system and the CML system cooperates with the accounting system (Premier).

I designed the architecture of the whole system—the client WPF application, CML (web application), Premier (a third-party accounting system), a synchronization job between CML and Premier, and a notification job (sends emails).

I also implemented the client application for Windows 8; it was based on WPF, but the whole app looks like a modern UI-styled application. The MVVM pattern was used during implementation.
2008 - 2011

Bachelor's Degree in Management of ICT Projects

Unicorn College - Prague, Czech Republic


LINQ, jQuery, jQuery UI, iTextSharp, Windows Forms (WinForms), RxJS, Entity Framework, Web API 2, SignalR, Moq, Log4Net, Infragistics, Web API, Chart.js, jQuery DataTables, NGXS, Stripe API, PrimeNG, React, Stripe, Node.js, REST APIs, Flexbox


Microsoft Visual Studio, TFS, SQL Management Studio, ReSharper, Dapper, Ninject, StructureMap, Visual Studio 2015, Visual Studio, Git, PostSharp, Slack, NPM, Webpack, TeamCity, Visual Studio 2019, Postman, JetBrains Rider, DataGrip, Sequelize, Jira


.NET, Entity Framework Core, Angular, ASP.NET, ASP.NET Web API, AngularJS, ASP.NET Identity, Entity, Bootstrap, Knockout (Knockout.js), Windows Presentation Foundation (WPF), NUnit, ASP.NET MVC 5, ASP.NET MVC, Unity, Kendo UI, Json.NET, ASP.NET Core, Windows PowerShell, Angular Material, Cypress, ASP.NET Web Forms, Jasmine, QUnit, Swagger, Redux, JSON Web Tokens (JWT), Express.js, Koa


TypeScript, C#, HTML, T-SQL (Transact-SQL), HTML5, Sass, CSS3, UML, Less, SQL, JavaScript, SCSS, CSS, XML, Python


Design Patterns, Model View ViewModel (MVVM), Object-oriented Programming (OOP), Generic Programming, Dependency Injection, Agile, Functional Programming, DRY, REST, DevOps, Management, CQRS, Scrum, Kanban, Unit Testing


Microsoft SQL Server, JSON, SQL Server 2016, MySQL, Databases, Elasticsearch, PostgreSQL


Windows, Azure, Telerik WPF, Telerik, SharePoint, Windows Server, Visual Studio Code (VS Code), Amazon Web Services (AWS), AWS Lambda


SOLID Principles, APIs, Full-stack, Integration, Windows Communication Foundation (WCF), DI, IIS, Azure Data Studio, CoreUI, Telerik WebForms Controls, Sequalize, Engineering, Web Development, Algorithms, HTTP, Storybook, Architecture, Front-end, Full-stack Development, Back-end, User Interface (UI), User Experience (UX), Email Marketing, Email Parsing, Web Scraping, Document Parsing, PDF, Web Security, Stripe Payments, Application State Management, Integration Testing

Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.


Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring