Pagy is a high-performance, agnostic pagination library for Ruby web applications (Rails, Sinatra, Rack) and any Ruby collection. It provides multiple pagination techniques: offset, keyset (cursor-based), countless (no total count), countish (cached count), calendar (time-based), and search backend integrations (Elasticsearch, Meilisearch, Searchkick, Typesense). The gem includes a rich set of view helpers for pagination navigation (series, input, limit, info) with Bootstrap, Bulma, and Tailwind CSS support, plus client-side JavaScript for responsive and interactive navs. Its architecture is modular: paginators and helpers are loaded on demand via a deferred loading pattern, and abilities (shiftable, rangeable, countable, linkable) are composed into paginator classes. The codebase is thoroughly tested (100% line/branch coverage, unit, API, and E2E tests) and highly optimized for speed and memory. It also provides a CLI, dev tools (PagyWand for CSS customization, Pagy AI assistant), and extensive documentation. The library is not a data research project; it is a production-ready software component.