alt Hacker NewsShow HN: Gander, an Android file viewer that asks for no permissions
Hi HN,
I built an Android file viewer that opens PDF, Word, Excel, PowerPoint, images, video, audio, Markdown and code, and asks for no permissions at all.
I have always been uneasy about opening files people send me. On Android you either install a 400 MB office suite and sign in or use a small free viewer that wants storage access and ends up uploading your file to a server to render it. Also the hassle of having to download different apps for different file formats was really annoying.
Gander holds no permissions, not even INTERNET so the OS itself guarantees the file cannot leave the phone.
PDFs use Pdfium, media uses Media3, and Office formats are rendered by bundled JS libraries in a WebView and so no request goes to any server.
It is a viewer only. Complex PowerPoint decks come out approximately right, spreadsheet charts are not drawn, and old binary .doc and .ppt are unsupported. I'll work on it as issues come up :P
It is 14 MB, MIT licensed and uploaded on Github releases.
Do try it! I would love some feedback especially on files that render badly or need new support.
Comments
Please add signature to readme so users can verify before installing with Obtainium eg:
5B:5C:F6:4A:94:23:7C:D5:F0:E0:85:76:00:38:BC:1C:EB:DF:18:DA:BA:5C:B3:EA:CA:7C:15:9F:22:A7:E2:4B
Tried it and I love it. Good work! Have you considered hosting it on F-Droid?
This looks great. It seems crazy how we got to this point where this is a revolutionary, unique product.
Thanks for sharing. Could it be possible to add optional force-dark mode for documents as well? The feature list mentioned dark mode, but that's for app's own UI. The really awesome feature would be to be able to invert the document colors so that the document itself is shown in dark mode. Thanks.
Can you add odt, ods, etc support? I use libreoffice viewer but it would be nice to reduce the number of apps on my device.
Could you publish to a store? Either/or Google Play or F-Droid
Going to test this out. I've been very happy to see the number of new apps being developed to be installed on android via obtanium and away from the Google app store. I assume it's llms enabling folks to get quick apps out.
Since everything is offline, what ended up being the hardest format to support while keeping rendering faithful?
The app is pleasingly very responsive. I don't think I've used anything else on Android that lets me open and close PDFs rapidly without getting bogged down. Nice!
Two things I really like:
1. Markdown loads as preview
2. Plain text files wrap instead of scrolling to the right
Good job and thank you for sharing
Can this open .rtf files?
I know it's old, but I still receive them from time to time.
Sounds great! You'll just need your social security or passport id sent to google to install and use it... sobs
This is super cool.
> Requirements: JDK 17+ and the Android SDK (platform 35).
Bummer. I am stuck with Android 14 for the moment.
Seems nice, will check it out. I liked this one as well: "Little File Explorer – File Manager for Android 1.0 and above" 28.dec.2023 https://news.ycombinator.com/item?id=38789958
I don't understand the comments to this post. Don't people use firewalls anymore to limit internet access only to the apps really needing it?
Great work! A tool like this is sorely needed.
How is accessibility? Do PDFs work with screenreaders for example?
This is a great idea - but doesn't Android inject network permission into all apks? It did in the past.
this is cool! It's amazing that it's still such a pain to do something like this with built-in Android app.
Well done!
> A tiny, open source, fully offline file viewer for Android that opens PDF, Word,
Perhaps correct Word to DOCX. Word is not just DOCX and DOCX is not just Word. This user needs DOC viewing and would be disappointed having installed this app.
I wish you every success with this.
This is cool!
Nice idea
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Great. You built an excellent tool to solve a real-world problem: being able to open files on the fly without granting internet access and without having to install 400 MB bloated suites that track everything.
This is interesting.
I thought granting internet access to apps is not avoidable on Android.
When an app does not request internet, is it really guaranteed that it cannot talk to the outside world? Or is it having other avenues like opening a browser or some other component with a custom url or something?
Update: I just asked Gemini, and it does not look good:
An Android app without the INTERNET permission is not guaranteed to be isolated from the outside world. While it cannot make direct network connections itself, it can use several other mechanisms to transmit data externally:
Intent-Based Communication (The Browser) An app can launch an explicit or implicit Intent to hand data over to another app that does have internet access.
That means the app can open a system browser using a URL containing the data it wants to transmit.
It can also load a Chrome Custom Tab inside its own UI task, passing data through the URL string.
There is also Inter-Process Communication: If two apps from the same developer share a User ID (sharedUserId), they run in the same process and share all permissions, including internet access.
There is also the concept of Content Providers: Content Providers allow apps to share data. An offline app can write data into a shared database or a public Content Provider. A secondary, online-enabled app can then read that database and upload the contents.