Introduction

Extend UI is an open source component library for building document processing interfaces. It gives teams the front-end primitives they need to preview, navigate, search, compare, and review the files that power real document workflows.

Extend is built around the work of turning raw PDFs, spreadsheets, scans, and text files into structured, production-ready data. Extend UI brings that same workflow mindset to product surfaces: start with reliable PDF, DOCX, and Excel viewers, then add the shared controls that help users inspect extracted content, validate outputs, resolve low-confidence fields, and move documents through review.

What belongs here

• Viewers for the file types document-heavy products need every day.
• Navigation primitives for pages, sheets, sections, images, and extracted text.
• Review surfaces for annotations, e-signature, and human-in-the-loop checks.
• Utility panels for OCR blocks, extraction status, and validation context.

Component set

The document-specific components are maintained in Extend UI. The rest of the base primitives are from Coss UI, including the shared button, tooltip, select, popover, dialog, and menu patterns. Icons come from Hugeicons.

Start with Components for the full list, or jump into Blocks for composed examples.