Dry-rb provides functional programming tools for Ruby. dry-validation creates complex validation schemas with type checking. dry-types defines strict types—coercion, constraints, sum types. I use dry-struct for immutable data structures with typed att

Refinements provide scoped modifications to existing classes without global monkey patching. I use refinements to add methods to core classes safely. Refinements activate with using statement—scope-limited to file or module. Unlike monkey patches, ref

Ruby 3+ introduces Ractors for true parallelism without GIL limitations. Ractors are isolated actors—no shared mutable state. I use Ractors for CPU-intensive parallel processing. Messages pass between Ractors via send and receive. Async gem provides s

ActionMailer handles email delivery in Rails. Mailers are similar to controllers—actions generate email content. I use ActionMailer for welcome emails, password resets, notifications. Layouts apply consistent styling across emails. Previews enable vie

ViewComponent brings component architecture to Rails views. Components encapsulate markup, logic, and tests in Ruby classes. I use ViewComponents for reusable UI elements—buttons, cards, modals, alerts. Components accept parameters via initializer, ke

Stimulus adds JavaScript behavior to HTML without building SPAs. Controllers attach to DOM elements via data-controller. I use Stimulus for modals, dropdowns, form validation, autocomplete. Actions connect events to controller methods via data-action.

Rails engines are miniature Rails applications within applications. I use engines for extracting reusable functionality—authentication, billing, admin panels. Engines have their own models, controllers, views, routes, migrations. Mountable engines are

GraphQL enables clients to request exactly the data they need. The graphql-ruby gem implements GraphQL servers in Rails. Types define data structures—ObjectTypes for models, InputTypes for mutations. Queries fetch data; mutations modify data. Resolver

Value objects represent immutable domain concepts without identity. I use value objects for money, addresses, date ranges, coordinates. Value objects are compared by value, not identity—two identical addresses are equal. They're immutable—create new i

ActiveStorage handles file uploads with cloud storage integration. It supports local disk, S3, Google Cloud Storage, Azure. Files attach to models via has_one_attached and has_many_attached. I use ActiveStorage for avatars, documents, images. Image va

Draper decorators encapsulate view-specific logic, keeping models clean. Decorators wrap models, adding presentation methods without polluting domain logic. I use decorators for formatting, conditional rendering, helper delegation. Decorators access h

rack-mini-profiler reveals performance bottlenecks in Rails apps. It displays database queries, rendering time, memory allocation on every page. I use Flamegraphs to visualize where time is spent. Memory profiling identifies allocation hotspots. Query