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Show HN: Extend UI – open-source UI kit for modern document apps
An open-source (MIT licensed) UI kit offering 14 components and examples for building modern document applications, including PDF, DOCX, XLSX viewers, bounding box citations, file upload, and e-signature, specifically designed for scale and robustness.
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AI Executive Synthesis
An open-source (MIT licensed) UI kit offering 14 components and examples for building modern document applications, including PDF, DOCX, XLSX viewers, bounding box citations, file upload, and e-signature, specifically designed for scale and robustness.
Extend UI addresses a significant developer pain point: the lack of robust, feature-rich, and scalable UI components for document-centric applications. The decision to open-source an internally developed solution, driven by customer demand, validates the market need. Its focus on handling "millions of pages/day" and fixing "edge cases" positions it as a production-grade solution, differentiating it from less mature alternatives. This UI kit is critical for building document processing agents, real-time intake flows, and internal tooling, aligning with the increasing demand for sophisticated document interaction in enterprise software. The MIT license and community support model foster adoption and continuous improvement, making it a valuable asset for developers in this domain.
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/kRmSGKRFWhen 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.
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Deep-Dive FAQs
What is Extend UI – open-source UI kit for modern document apps?
Extend UI – open-source UI kit for modern document apps is analyzed by our AI as: An open-source (MIT licensed) UI kit offering 14 components and examples for building modern document applications, including PDF, DOCX, XLSX viewers, bounding box citations, file upload, and e-signature, specifically designed for scale and robustness.. It focuses on Extend UI addresses a significant developer pain point: the lack of robust, feature-rich, and scalable UI components for document-centric applicati...
Where did Extend UI – open-source UI kit for modern document apps originate?
Data for Extend UI – open-source UI kit for modern document apps was aggregated directly from the Hacker News community ecosystem, representing raw developer and early-adopter sentiment.
When was Extend UI – open-source UI kit for modern document apps publicly launched?
The initial public indexing or launch date for Extend UI – open-source UI kit for modern document apps within our tracked developer communities was recorded on June 11, 2026.
How popular is Extend UI – open-source UI kit for modern document apps?
Extend UI – open-source UI kit for modern document apps has achieved measurable traction, logging over 166 traction score and facilitating 41 recorded discussions or engagements.
Which technical categories define Extend UI – open-source UI kit for modern document apps?
Based on metadata extraction, Extend UI – open-source UI kit for modern document apps is categorized under topics such as: open-source UI kit, PDF, DOCX, and XLSX viewers, bounding box citations, file upload.
What are some commercial alternatives to Extend UI – open-source UI kit for modern document apps?
Our semantic intelligence engine identifies potential commercial alternatives in the SaaS space, such as Trump Accounts, which offers overlapping value propositions.
How does the creator describe Extend UI – open-source UI kit for modern document apps?
The original author or development team describes the product as follows: "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 vi..."
Community Voice & Feedback
This is really interesting. Thanks for creating this.
How is your PDF coverage? They are notoriously difficult things to render, with endless edge cases.
Mozilla’s PSD.js is the status quo here, so what do you do better than them?
Mozilla’s PSD.js is the status quo here, so what do you do better than them?
Looks cool but your home page heavily lags on my mbp m3 pro - you should maybe be lazy loading vs loading all your components upfront
Cool project! I was playing around with the Excel viewer - the docs claim "Search across sheets and cell ranges", but I can't seem to trigger search functionality and the browser search bar can't find contents on cells.Is this a known issue?
How does it compare to https://news.ycombinator.com/item?id=48436863 ?
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.
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! :)
Why doesn't it mention anywhere that they are React components?
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...
These should really be web components. Leaving out every framework other than React is really bad for the web.
Discovery Source
Hacker News Aggregated via automated community intelligence tracking.
Tech Stack Dependencies
No direct open-source NPM package mentions detected in the product documentation.
Media Tractions & Mentions
No mainstream media stories specifically mentioning this product name have been intercepted yet.
Deep Research & Science
No direct peer-reviewed scientific literature matched with this product's architecture.