Core: Ruby 3.x, Rails 7, ActiveRecord, ActionMailer, ActiveJob. Frontend: Hotwire, Turbo, Stimulus, ERB, Haml, ViewComponent. Database: PostgreSQL, MySQL, SQLite. Caching: Redis, Memcached. Background Jobs: Sidekiq, Delayed Job, Resque. Testing: RSpec, Minitest, FactoryBot, Capybara. API: Grape, ActiveModel Serializers, GraphQL with graphql-ruby. Authentication: Devise, OmniAuth, JWT. Search: Elasticsearch, Algolia, pg_search. File Storage: ActiveStorage with AWS S3, Cloudinary. Deployment: Heroku, AWS, Capistrano, Docker, Kamal. CI/CD: GitHub Actions, CircleCI, Travis CI. Frontend integration with React, Angular, Vue.js.