Show HN: Extend UI – open-source UI kit for modern document apps

Hacker News Top Tools
open-source ui-kit document-viewer pdf docx xlsx file-upload

Summary

Extend UI is an open-source UI kit for modern document apps, providing viewers for PDF, DOCX, XLSX, and CSV files, along with features like bounding box citations, file upload, and e-signing.

We&#x27;re open-sourcing 14 components &amp; examples today for PDF, DOCX, and XLSX viewers, plus bounding box citations, file upload, e-signature, and more. It&#x27;s MIT licensed and fully customizable.<p>Demo video here: <a href="https:&#x2F;&#x2F;share.extend.ai&#x2F;kRmSGKRF">https:&#x2F;&#x2F;share.extend.ai&#x2F;kRmSGKRF</a><p>When we started, we tried every file viewer and document component library we could find. Unfortunately, none of them had all the functionality (and polish) that we wanted, so we ended up building our own for <a href="https:&#x2F;&#x2F;extend.ai&#x2F;">https:&#x2F;&#x2F;extend.ai&#x2F;</a>. It was only ever meant to be internal, but enough customers kept asking for it that we decided to open source it.<p>It&#x27;s useful for building document processing agents, real-time user facing document intake flows, or all kinds of internal tooling.<p>We naively thought this would be a solved problem. Turns out, making PDF&#x2F;XLSX&#x2F;DOCX viewers that work at scale is not trivial...we use and maintain it for Extend ourselves, so we&#x27;ve fixed a lot of edge cases that came up while running millions of pages &#x2F; day through our own system. Our hope is that with our resources + community support, it&#x27;ll keep getting better over time.
Original Article
View Cached Full Text

Cached at: 06/10/26, 08:47 PM

# Open source UI kit for modern document apps - Extend UI Source: [https://www.extend.ai/ui](https://www.extend.ai/ui) File viewers for PDF, DOCX, XLSX, and CSV, with bounding box citations, file upload, e\-signing, and more\. Ready to drop into user\-facing flows, agents, or internal tools\. [View full examples](https://www.extend.ai/ui/blocks)[View components](https://www.extend.ai/ui/docs/components) ![Document component previews](https://www.extend.ai/ui/_next/image?url=%2Fui%2Fimages%2Froot-components-showcase-light-v2.png&w=3840&q=75&dpl=dpl_Ba1ENTS9jPKp7oc7XHXwvvW8mLGq)![Document component previews](https://www.extend.ai/ui/_next/image?url=%2Fui%2Fimages%2Froot-components-showcase-dark-v2.png&w=3840&q=75&dpl=dpl_Ba1ENTS9jPKp7oc7XHXwvvW8mLGq) PDF Viewer [View](https://www.extend.ai/ui/docs/components/pdf-viewer) Document Splits [View](https://www.extend.ai/ui/docs/components/document-splits) XLSX Viewer [View](https://www.extend.ai/ui/docs/components/xlsx-viewer) File System [View](https://www.extend.ai/ui/docs/components/file-system) DOCX Viewer [View](https://www.extend.ai/ui/docs/components/docx-viewer) File Thumbnail [View](https://www.extend.ai/ui/docs/components/file-thumbnail) Image ![](https://www.extend.ai/ui/opengraph-image.png) PDF DOCX XLSX Schema Builder [View](https://www.extend.ai/ui/docs/components/schema-builder) Property keyTypeDescriptionValueDescription Property keyTypeDescriptionProperty keyTypeDescription Property keyTypeDescription PDF Viewer [View](https://www.extend.ai/ui/docs/components/pdf-viewer) Document Splits [View](https://www.extend.ai/ui/docs/components/document-splits) File System [View](https://www.extend.ai/ui/docs/components/file-system) DOCX Viewer [View](https://www.extend.ai/ui/docs/components/docx-viewer) File Thumbnail [View](https://www.extend.ai/ui/docs/components/file-thumbnail) Image ![](https://www.extend.ai/ui/opengraph-image.png) PDF DOCX XLSX XLSX Viewer [View](https://www.extend.ai/ui/docs/components/xlsx-viewer) Schema Builder [View](https://www.extend.ai/ui/docs/components/schema-builder) Property keyTypeDescriptionValueDescription Property keyTypeDescriptionProperty keyTypeDescription Property keyTypeDescription Layout Blocks [View](https://www.extend.ai/ui/blocks#layout-blocks) Bounding Box Citations [View](https://www.extend.ai/ui/blocks#bounding-box-citations) File System [View](https://www.extend.ai/ui/blocks#file-system) XLSX Viewer [View](https://www.extend.ai/ui/blocks#excel-document-splits) File Upload [View](https://www.extend.ai/ui/blocks#pdf-dropzone) DOCX Editor [View](https://www.extend.ai/ui/blocks#docx-editor-block) E\-Signature [View](https://www.extend.ai/ui/blocks#e-signature)

Similar Articles