Krzysztof is available for hire

Krzysztof Łabuś

Verified Expert in Engineering

Software Developer

Location

Kraków, Poland

Toptal Member Since

October 3, 2022

Krzysztof is a senior .NET developer experienced in software architecture design and site reliability. He has implemented highly available, distributed, fault-tolerant, and disaster-resilient systems and has led teams of talented engineers specializing in .NET, quality assurance, and mobile developers.

Web Security Web Development Back-end Security Code Review Scalability OAuth Amazon RDS SQL JSON Databases .NET C#REST APIs C#.NET Fault Tolerance Netty OpenID Connect

Portfolio

Radix DLT

C#, ASP.NET Core, .NET Core, .NET 6, High Availability Disaster Recovery (HADR)...

Toptal Client

.NET Core, C#, Docker, SAML, Identity Server, Okta, SAML-auth...

Sinch

.NET, Amazon Simple Queue Service (SQS), Micro SOA, OpenID Connect (OIDC)...

Experience

APIs - 8 years C# - 8 years .NET - 8 years Docker - 6 years Architecture - 6 years High Availability Disaster Recovery (HADR) - 4 years Site Reliability Engineering (SRE) - 4 years Distributed Software - 4 years

Availability

Full-time

Preferred Environment

.NET, C#, High Availability Disaster Recovery (HADR), Site Reliability Engineering (SRE), Fault Tolerance, Amazon Web Services (AWS), SQL, Redis, RabbitMQ, Resilient Distributed Datasets (RDD), GraphQL

The most amazing...

...project I've led lifted customer service to multi-regional, highly available service handling worldwide traffic and increased SLA from 98.5 to 99.995.

Work Experience

Senior .NET Developer

2022 - PRESENT

Radix DLT

Reduced database read and write times by order of magnitude, decreasing overall request processing time.
Redesigned underlying data storage layer to meet expected load.
Fine-tuned PostgreSQL database set up and how the application writes bulks of data (over 5,000 records a second) into it.

Technologies: C#, ASP.NET Core, .NET Core, .NET 6, High Availability Disaster Recovery (HADR), SQL, PostgreSQL, Redis, Distributed Software, APIs, Integration, API Integration, DevOps, Architecture, CI/CD Pipelines, Software Architecture, Swagger, Docker Compose, Web Security, ASP.NET, ASP.NET MVC, Amazon Web Services (AWS), REST, Algorithms, Databases, Cloud, Web Development, Software Design, Scalable Architecture, Fintech, Engineering, Back-end, Security, Code Review, Amazon ElastiCache, Technical Project Management, Kubernetes, Microservices, NoSQL, API Gateways, Terraform, AWS Cloud Development, Amazon RDS, Amazon EC2, Scalability, Web Architecture, Continuous Integration (CI), Cloud Architecture, Enterprise Architecture, Solution Architecture, C#.NET, SOLID Principles, Technical Consulting, Technical Architecture

C#/.NET Developer

2023 - 2023

Toptal Client

Modernized outdated projects to the most up-to-date.NET/IdentityServer versions.
Integrated in-house developed IdentityServer with external IdentityProviders such as Okta and Azure AD into a single SSO solution.
Integrated SCIM-based data exchange with external IdentityProviders such as Okta and Azure AD.
Modernized front-end applications to make use of dedicated back-end services for better security and authentication with a dedicated back end for-front end.

Technologies: .NET Core, C#, Docker, SAML, Identity Server, Okta, SAML-auth, OpenID Connect (OIDC), .NET, Amazon Elastic Container Service (Amazon ECS), Single Sign-on (SSO), Authentication, Authorization, APIs, SCIM, OpenID, Serverless, TypeScript, Solution Architecture, C#.NET, SOLID Principles, Technical Consulting, Identity & Access Management (IAM), Technical Architecture

Technical Team Leader, Solution Architect, .NET Developer

2018 - 2022

Sinch

Supervised the complete software development lifecycle (SDLC) for the projects I led, including cross-team dependency management, roadmap planning up to daily releases, and quarterly OKR reports.
Lifted and modernized outdated systems to more modern standards, boosting development velocity and engagement of all developers.
Reduced latency for one of the mission-critical services from 300-400 milliseconds (ms) down to a 10-50 ms range per transaction.
Created fault-tolerant, highly-available distributed applications that communicate across multiple regions (data centers).
Increased service throughput by orders of magnitude using asynchronous, eventually consistent architecture for the newly developed solutions.

Technologies: .NET, Amazon Simple Queue Service (SQS), Micro SOA, OpenID Connect (OIDC), Amazon Simple Notification Service (Amazon SNS), Amazon DynamoDB, Team Leadership, HTTP, APIs, REST APIs, API Integration, Swagger, Docker Compose, Web Security, ASP.NET, ASP.NET MVC, Amazon Web Services (AWS), REST, Algorithms, Databases, Cloud, Web Development, Software Design, System Architecture Design, Project Planning, Technical Consulting, Scalable Architecture, C#, Engineering, Leadership, Back-end, Microsoft SQL Server, OAuth, Security, Code Review, Elasticsearch, Solr, Amazon ElastiCache, Amazon OpenSearch, Technical Project Management, Amazon S3 (AWS S3), Microservices, NoSQL, API Gateways, Terraform, AWS Cloud Development, Amazon RDS, Amazon EC2, Scalability, Web Architecture, Continuous Integration (CI), Technical Leadership, Cloud Architecture, Project Management, Identity Server, Enterprise Architecture, OpenID, ELK (Elastic Stack), Solution Architecture, C#.NET, SOLID Principles, Identity & Access Management (IAM), Technical Architecture

Senior .NET Developer

2013 - 2018

Grupa Pracuj

Developed and maintained a TV-advertised website where traffic jumped by a factor of 100-300 times after the commercial aired. Oversaw infrastructure costs.
Introduced SSO-based authentication for the bulk of websites under entirely different TLDs.
Led the transition of the PHP-skilled team to a .NET-based ecosystem.

Technologies: PHP, C#, .NET, .NET Core, Symfony, Varnish, Linux, NGINX, Windows Server, Azure, OpenID Connect (OIDC), Single Sign-on (SSO), Authentication, Authorization, Integration, APIs, Apache, MySQL, PostgreSQL, Netty, WebSockets, Technical Leadership, HTTP, JSON, REST APIs, Swagger, Docker Compose, Web Security, ASP.NET, ASP.NET MVC, REST, Algorithms, Databases, Cloud, Web Development, Software Design, System Architecture Design, Engineering, Leadership, Back-end, Microsoft SQL Server, OAuth, Security, Code Review, Elasticsearch, Solr, Amazon ElastiCache, Amazon OpenSearch, JavaScript, CSS, HTML, Technical Project Management, TypeScript, Kubernetes, Microservices, NoSQL, Terraform, Scalability, Web Architecture, Continuous Integration (CI), Cloud Architecture, Project Management, Identity Server, Enterprise Architecture, OpenID, Unix, Angular, Cron, SOLID Principles

Experience

Phone Number Verification Service

https://www.sinch.com/products/apis/verification/

I led technical maintenance, modernization, and development of this entire product with a team of 6-8 people. I coordinated cross-team dependencies and was involved in operational monitoring. During my presence, this product grew in gross revenue and volume of served traffic several times. Its availability jumped from 98-99% to 99.995%, and latencies went down from 300-400 milliseconds to 10-50 milliseconds per transaction.

Pracodawcy.pracuj.pl

https://pracodawcy.pracuj.pl/

Profile-like system for Pracuj.pl customers where they can promote and advertise their businesses and job offers posted on Pracuj.pl. I was responsible for overall architecture design for this website.

Skillset

Languages

C#, SQL, C#.NET, GraphQL, TypeScript, PHP, JavaScript, CSS, HTML, SAML

Frameworks

.NET, .NET Core, ASP.NET Core, ASP.NET, ASP.NET MVC, Swagger, Angular, Symfony, Netty

Libraries/APIs

REST APIs, OpenID

Tools

RabbitMQ, Amazon Simple Queue Service (SQS), Amazon ElastiCache, Terraform, Amazon Simple Notification Service (Amazon SNS), Docker Compose, Amazon Elastic Container Service (Amazon ECS), Varnish, NGINX, Apache, ELK (Elastic Stack), Cron, Solr, Amazon OpenSearch

Paradigms

Continuous Integration (CI), Continuous Development (CD), REST, Microservices, Web Architecture, DevOps

Platforms

Amazon EC2, Docker, Amazon Web Services (AWS), Unix, Linux, Azure, Windows Server, Kubernetes

Storage

Redis, JSON, Databases, PostgreSQL, MySQL, Amazon DynamoDB, Microsoft SQL Server, Amazon S3 (AWS S3), NoSQL, Distributed Databases, Elasticsearch

Other

Micro SOA, OpenID Connect (OIDC), APIs, .NET 6, Architecture, Software Architecture, HTTP, Technical Leadership, SOLID Principles, Web Security, Web Development, Software Design, Engineering, Back-end, OAuth, Security, Code Review, Amazon RDS, Scalability, Identity Server, Enterprise Architecture, Technical Architecture, High Availability Disaster Recovery (HADR), Site Reliability Engineering (SRE), Resilient Distributed Datasets (RDD), Low Latency, Distributed Software, Integration, API Integration, CI/CD Pipelines, Single Sign-on (SSO), Solution Architecture, Team Leadership, Algorithms, Cloud, System Architecture Design, Project Planning, Technical Consulting, Scalable Architecture, Leadership, Technical Project Management, API Gateways, AWS Cloud Development, Cloud Architecture, Identity & Access Management (IAM), Fault Tolerance, Distributed Systems, Authentication, Authorization, WebSockets, Fintech, SAML-auth, Okta, SCIM, Serverless

Industry Expertise

Project Management

Collaboration That Works

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