Reading the title, I almost dismissed this as it is talking about Markdown support. But when I read the request, there are several items in here that are important to me and it has a healthy amount of upvotes. So I wanted to share some thoughts... According to some of the requests, this is for offline caching and editing in addition to markdown format. And for some it is for Markdown support. I think this is actually a variety of requests, which generally get a response of "Please stick to one idea per request" from Proton (and any software development team).

To that end let's clarify which platform this is being requested for: web browser, mobile, desktop client.
- Regards offline ability. Let me be very clear, this is SUPER important to my use cases. My entire career, a significant amount of time, has been spent in environments with, at best unreliable internet. At worst none for hours of work and/or travel.
- What doesn't work at all in any offline scenario is Proton Docs and Sheets.
- In my experience, the offline experience works fine on desktops. I do edit all sorts of file formats on the desktop when the computer is offline by using the make available offline. And yes, Markdown is one of those formats.
- On mobile client, that also works, but is a horrible experience. Steps: cache on device, go offline, download file(s), edit file(s), upload file(s). Part of this is absolutely Proton's security design to prevent 3rd party apps from scanning (uploading) all files. But then again doing any serious work on a 4 inch screen is awful, so it only happens in a pinch.
- Offline browser support. For the sake of completeness there should be a clarification as to whether this request is for a desktop web browsing or mobile web browsing experience. That said, I've never seen any but the simplest "offline web browser" based application work reliably in the decades that web browsers and app developers have tried to use the browser to deliver local applications.
- The second is document format support.
- In a mobile scenario, when I think about how this applies to my use case and something that will benefit the most users, I would like to see Proton Docs and Sheets be supported offline. Also, the user experience of loading a Proton Doc/Sheet as a web app is really slow compared to the built-in PDF reader.
- In a desktop scenario, I would also like to have the ability to view/edit Proton Docs/Sheets offline.
- on the mobile platform, I would also like to see basic text editing TXT, Markdown, RTF, etc. where I can easily put together a pleasantly formatted document that I can send to someone over e-mail or another scenario that supports offline usage, yet still store it on Proton Drive without having to jump through the hoops above.
- Regarding other document formats... I'm lending my support to feature requests accelerating integration of Standard Notes.

To that end, these are the specific work items on user voice that I could find for the areas of this request I broke down above. Just in case other's haven't found these and/or voted on them:
- Proton Drive offline editing support for Proton Docs - https://protonmail.uservoice.com/forums/932839-proton-drive/suggestions/48610982-offline-editing-support-for-documents-in-proton-dr
- Paste Markdown into Docs (currently copying from is supported) - https://protonmail.uservoice.com/forums/932839-proton-drive/suggestions/50648297-paste-markdown-into-docs
- Docs: Preserve RTF/HTML formatting on paste or load - https://protonmail.uservoice.com/forums/932839-proton-drive/suggestions/51136852-docs-preserve-rtf-html-formatting-on-paste-or-l
- Support reading/editing TXT documents in Proton Drive (Mobile) - https://protonmail.uservoice.com/forums/945460-general-ideas/suggestions/51326755-support-reading-editing-txt-documents-in-proton-dr

For the folks who want Markdown ability in mobile/desktop/desktop web/desktop mobile as supported format I would suggest creating another user voice request that specifies the specific scenario and platform you want the ability to handle markdown editing. In that new user voice request link back to this suggestion so that the development team can see how many people want Markdown in general. I would also suggest adding a link to the specific scenario to this thread.

Bumping this to "critical" for the "How important is this to you?" question. Just hit another situation where this is making Proton Drive less useful. Please add support for editing and saving files as plaintext/markdown.

Yes, please! Consider this another vote in favor of supporting markdown files for viewing/editing via the browser-based Proton Drive app AND sync'ing to local machines.

Yes please. Markdown is sometimes all you need for writing formatted plain-text. Adding a "preview" mode may be secondary. But just simply supporting plain text (.txt) or Markdown (.md) in Proton Drive is already a good start, if it will be allowed. Not everything text-based should go through the "Word Doc" editor.

With you here, as a Vim markdown user, I would like for those to render properly in Proton Drive.

If you add support for markdown, then please, make it work something like Nuclino. It wouldn't take much. Add support (in the webapp) for displaying files on the left. When you click on a file, display it on the right (not in a separate window). You could also do this for text files and images.

Then you've got a killer app. Not only does it replace Google Drive for the majority of people, but you've also got a combined note taking app. This is what I really want - I pay for Google Drive (I have a lot of files) and Nuclino, but I really want an app that combines the two.

I totally agree with you. Working offline with simple and flexible formats like markdown makes a huge difference in productivity. Having better control over documents without depending completely on an online editor would be amazing. Similarly, when dealing with important online processes like Samagra ID verification, having a clear step-by-step guide really helps. I found this resource quite useful for understanding the KYC process: https://samagraidgyaan.com/samagra-id-kyc/
— it keeps everything organized and easy to follow.

I handle this by using Obsidian locally to edit / view Markdown files stored on Proton Drive.

What I'd like to see is Markdown / text editing support in the Proton Drive Web app. It's odd that you can't even preview MD files stored in Drive.

Extremely useful. Most rudimentary and simple way to create markup yet keep it readable without an interpreter - makes it perfect as an exchange format both between machines and humans alike.

This is a key use case for me. Supporting Markdown is important because it enables cross-device synchronization. It allows important information to be edited directly on a mobile device or via the web without creating an additional Proton Doc file. In addition to working across devices, it is also cross-platform: these Markdown files can be opened smoothly on both macOS and Windows. Furthermore, the Markdown files can be regularly backed up to a portable hard drive, reducing concerns about format compatibility when accessing them in the future.

If this matters to you, feel free to upvote this :)

Came here because I wanted something similar, but now I'm no so sure. It seems like what you want more than "markdown support" is offline mode where md files sync between Drive and local with Drive appropriately rendering md in the cloud. Is that right?

I'm a Linux user and don't have a Proton Drive desktop app yet, so I'm not sure I understand what you mean when you describe your workflow and "local representations." It seems to me a Proton Doc is a specific format more than text renderer. Just guessing because I can download a Proton Doc in a docx, html, txt, md, or pdf as of mid-Jan 2026, but cannot tell Proton Drive which format of file I want to create when I create a new file in the cloud.

I'm uncertain if Proton would consider this "markdown support" already. I'm not sure I do because if I understand your idea it sounds really cool.

I agree. This would be very useful, but as someone else said, just plain text support would be a good start.

just edit plain text md file would be great. Preview or style can arrive later

I like the existing support for markdown in proton docs (import, export, auto-detecting syntax)

But, it would also be handy to be able to edit a *.md file in-place, or any other plain-text file.

Would be a nice to have! Currently still using Dropbox for my Obsidian Notebook as I can edit the markdown files in that app.