Building applications in Ruby on Rails from version 3.0.x-8.0.x to the most recent.

Programming applications in Ruby from version 1.8.7-3.5.x to the most recent.

Programming applications in Python: DevOps, machine learning and data-related works.

Programming applications in Golang: fast and efficient CLI and API solutions

Programming applications in Rust fast and efficient solutions

Static pages with Jekyll (in Ruby), Hugo (in Golang) or Rust.

Integrating various number of templates: Liquid, Handlebars.js, ERB, HAML, Slim etc.

Data Extraction from the Web: scrapy, selenium, nokogiri, BeautifulSoup

Building MVP, quickly and efficiently.

Programming applications in JavaScript fast and efficient web and server solutions in Stimulus, Vue.js, React, Backbone.js, jQuery and Node.js

Responsive and mobile friendly websites in HTML5 and JavaScript.

Refactoring outdated projects, security fixes, upgrades, refactoring legacy code, increasing code quality.

Integrating CI/CD pipelines into existing and new applications: Bitbucket CI, Jenkins, AWS CodePipeline, CircleCI, GitLab, GitHub.

Upgrading outdated projects and server infrastructure.

Experience in maintaining web applications.

Setting up and maintaining mailbox solutions like Postfix, Qmail, Sendmail, Mailcow etc.

Experience in scaling up/out web applications.

Running and maintaining applications on Docker.

Testing and maintaining applications using Domain Driven Design methodology.

Testing and maintaining tests: controllers, models, integrations, and acceptance testing.

Building REST APIs

Setting up and maintain Linux on desktop and server: Debian, Ubuntu, etc.

Setting up and maintain caching solutions.

Using Git repositories for years in daily work.

Frontend development in HTML5, CSS and JavaScript frameworks.

Server side and backend development work.

Optimize queries, detecting slow queries and scaling databases.

Setting up and maintaining MySQL databases

Setting up and maintaining PostgreSQL databases

Setting up and maintaining services in Google Cloud infrastructure.

Setting up and maintaining services in Amazon Web Services (AWS) infrastructure.

Setting up and maintaining services in DigitalOcean infrastructure.

Setting up and maintaining services in Hetzner Cloud infrastructure.

Setting up and maintaining services in Heroku infrastructure.

Setting up, maintaining dedicated servers and VPS.

Setting up and maintaining Nginx servers.

Setting up and maintaining production Ruby on Rails applications on: Mongrel, Thin, Unicorn, Puma.

Setting up, maintaining dedicated servers and VPS.

Building microservices in Amazon Lambda.

Integrating Amazon S3 buckets.

Building web services in Amazon EC2 infrastructure.

Building in Cloudflare Workers and Pages.

Integrating Cloudflare R2 buckets.

Database sharding, vertical and horizontal scaling, replication.

MongoDB setup and integrations with applications.

Redis setup and integrations with applications.

InfluxDB setup and integrations with applications.

Elasticsearch setup and integrations with applications.

Sphinx search setup and integrations with applications.

Manticore search setup and integrations with applications.

Building and maintaining ruby gems from scratch.

Integrating payments solutions like Stripe, PayPal, Braintree etc.

Working with Big Data. Experience in working with more than 1M records.

Shopify Apps setup and integrations with applications.

Advance SEO services and techniques.

Building API client and implementing trading strategies in Python and Ruby.

Back testing and implementing trading strategies in Python.

Experience in using GitHub services.

Experience in using GitLab services.

Creating responsive, clean, and good-looking interfaces in Tailwind and Bootstrap.

Security scanning for vulnerabilities

Implementing real-time protocol (MQTT, EventMachine, Ably, Pusher, Action Cable, Redis)

2FA implementation (WebAuthn, OTP etc.)

Statistical analyze in Python (NumPy, Pandas, matplotlib)

Twilio integrations: SIP, VoIP, SMS, Calls

Plivo integrations: SIP, VoIP, SMS, Calls

Integrate web services with popular APIs: Mailgun, Postmark, SendGrid, Amazon SES.

Kamailio SIP setup and maintenance.

GraphQL and web integrations.

Hardware base systems with API and website to manage external devices (intercoms, servers, parcel lockers, apps), touch screens and All-in-One PC