UnderStrap

For developers building custom WordPress themes, Understrap is a free, open-source framework that merges the backend best practices of Underscores with the responsive frontend of Bootstrap. It is used by over 100,000 sites for its clean, flexible, and performant codebase.

• Combines Underscores and Bootstrap: Get the lightweight, minimalist starter theme from Automattic on the backend and Bootstrap 4's grid, components, and utilities on the frontend for rapid mobile-first development.
• Child theme ready: The included child theme structure lets you customize and extend functionality without modifying the parent theme, ensuring easy updates.
• Lightweight and fast: Understrap is built for performance with no bloat, resulting in fast page loads that benefit SEO and user experience.
• Professional open-source support: Maintained by Howard Development & Consulting with a dedicated team, offering the stability of a backed project along with open-source flexibility.
• Easy customization: Well-organized, commented code makes it simple to add custom templates, sections, and styling to match any design.