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

6 hours ago (extend.ai)

We're open-sourcing 14 components & examples today for PDF, DOCX, and XLSX viewers, plus bounding box citations, file upload, e-signature, and more. It's MIT licensed and fully customizable.

Demo video here: https://share.extend.ai/kRmSGKRF

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 https://extend.ai/. It was only ever meant to be internal, but enough customers kept asking for it that we decided to open source it.

It's useful for building document processing agents, real-time user facing document intake flows, or all kinds of internal tooling.

We naively thought this would be a solved problem. Turns out, making PDF/XLSX/DOCX viewers that work at scale is not trivial...we use and maintain it for Extend ourselves, so we've fixed a lot of edge cases that came up while running millions of pages / day through our own system. Our hope is that with our resources + community support, it'll keep getting better over time.

17 comments

kbyatnal

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dvt  1 hour ago

Super cool. Working on a local AI tool specifically for document workflow automation (where context = screen/web/folders/files), and this could come in super useful. I do most of the PDF/DOCX/etc. parsing natively in Rust, but having a nice way to see the output without spinning up Word or Powerpoint is a huge leap.

Thanks for releasing publicly.

spankalee  3 hours ago

These should really be web components. Leaving out every framework other than React is really bad for the web.

  • andrewlu0  2 hours ago

    thats fair and definitely something we can try supporting in the future. we started with React because of how familiar models are with shadcn and tailwind

    we hope this can be useful for people building in React though!

CraigJPerry  2 hours ago

Those bounding box demos are decent.

By quirk of fate i've spent the past 2 days prototyping some stuff on pdfjs. Just trying to figure out a game plan for handling bounding boxes in the face of page zooming, different resolutions etc. etc. I can't see it mentioned whether the components are virtualising pages (as in reusing dom elements as document pages scroll by). I guess i just learned what i'll be exploring tomorrow then...

  • andrewlu0  2 hours ago

    yes - the pdf/docx viewer use react-virtual to virtualize the pages

    the zoom should work with the bounding box highlights, we're working on adding rotation support

hobofan  1 hour ago

Thanks, that looks awesome! We were looking to add DOCX and XLSX preview to our app, and were planning to do server-side conversion to PDF (which seems to be what most other apps resort to) due to the lack of good libraries to render it, and this is exactly what we were looking for! :)

  • andrewlu0  1 hour ago

    thanks! would love to get your feedback

    i can't promise its visually 1:1 with Word/Excel but its pretty close on the corpus we tested with

warthog  3 hours ago

really like these - curious how the xlsx editor and viewer is built in that what kind of headless spreadsheet?

could not have been easy

  • andrewlu0  3 hours ago

    Hi! I'm one of the engineers at Extend that worked on this - one of our other engineers created a Rust XLSX/XLS parser that we ported to WASM to our @extend-ai/react-xlsx package which handles the rendering/charts. It exposes some hooks so users can use their own components for the toolbar