A markdown viewer for Opera that just works
Why raw markdown looks like a wall of text
A markdown file, the kind ending in .md, is plain text with a few formatting marks mixed in: # for a heading, **bold** for bold, - for a list item, and pipes and dashes for tables. Opera does not understand those marks on its own. Open a .md file in a fresh tab and Opera either downloads it or shows the raw text, symbols and all, as one long unformatted block. Nothing is broken. Opera simply has no built-in markdown viewer, so it shows you the source instead of the page the source describes.
A markdown viewer for Opera fixes that. It sits in the browser, notices when a page is markdown, and turns those marks into a formatted document: real headings, readable tables, highlighted code, working links. You open the file the way you always would, and it arrives as a clean page instead of a symbol soup.
Skim: a free, open-source markdown viewer for Opera
Skim is a free, open-source extension that renders markdown automatically. Once it is installed, any .md file you open, whether it is a URL on the web, a README, or a local file on your own disk, opens as a formatted page. There is no button to press and no menu to find. Skim recognizes markdown and renders it for you.
It is MIT-licensed, so the source is public and anyone can read exactly what it does. It collects no data, runs no telemetry, and makes no network calls on your behalf. Everything renders on your device. Opera is built on Chromium, so it runs the same extension the rest of the Chromium family does, installed straight from the Chrome Web Store.
How to add it to Opera
Opera has its own add-on gallery, but it also installs extensions from the Chrome Web Store through one small official helper. Setup takes about two minutes, most of it a one-time step.
- Add the "Install Chrome Extensions" add-on from Opera's own gallery, if you do not already have it. This is Opera's official bridge to the Chrome Web Store, and it adds an "Add to Opera" prompt to Chrome Web Store listings.
- Open Skim's Chrome Web Store listing and click "Add to Opera". Opera installs it like any other add-on, with one confirmation.
- Flip Opera's file-access switch. Opera hides local files from extensions by default, exactly like Chrome, so to read
.mdfiles from your own disk it needs your permission once. Skim shows you exactly where to click, so you are not hunting through settings. - Open any
.mdfile from now on. It renders as a formatted page automatically, every time, with no extra steps.
If you only ever open markdown files on the web and never local ones, you can skip the file-access step entirely. That switch only matters for files stored on your own computer.
What Skim can do
A viewer is only as good as what it renders. Skim aims to handle the markdown people actually write, not a stripped-down subset:
- Live reload. Skim watches the file and re-renders it in place the moment it changes on disk. Leave an AI agent's plan open in a tab and watch it tick off tasks in real time, no manual refresh, with your scroll position kept.
- KaTeX math. LaTeX expressions render as real equations instead of raw backslashes and braces.
- Mermaid diagrams. Flowcharts and sequence diagrams written as code render as actual diagrams.
- GFM tables. GitHub-flavored markdown tables, task lists, footnotes, and syntax-highlighted code blocks all render correctly.
- Folder view. Browse a whole project of markdown files from a sidebar, free, with no Pro tier gating it.
- Copy as markdown. One click turns the rendered page back into clean markdown source, ready to paste into your next prompt or document.
- Private and on-device. Files never leave your machine. No account, no telemetry, no data collected, and it all works offline.
No install? Read it online instead
If you only need to read one file and would rather not add anything to Opera, there is a no-install option. The free online markdown viewer renders any .md file you drag onto the page, right in the browser, with nothing uploaded. It works on a work laptop, a phone, or a computer you do not own. For a file you will open once, that is genuinely the fastest route. For files that keep landing in your downloads folder, the extension is the better long-term fix, because after setup every file just works.
FAQ
Does Opera have a built-in markdown viewer?
No. Opera shows a .md file as raw text or downloads it, because it has no built-in way to render markdown. You need an extension like Skim, or an online viewer, to see it as a formatted page.
How do I install a Chrome Web Store extension in Opera?
Add Opera's official "Install Chrome Extensions" add-on from its gallery once. After that, any Chrome Web Store listing, including Skim's, shows an "Add to Opera" button that installs the extension for you.
Is the Skim markdown viewer free?
Yes. Skim is MIT open source and completely free, with no Pro tier, no paywall, and no account. Features that some other viewers charge for, like folder browsing, are free in Skim.
Can it read local .md files from my computer?
Yes. After you flip Opera's file-access switch, which Skim walks you through once, it renders local .md files exactly like ones on the web. Nothing is uploaded.
Does Skim collect any data?
No. Skim renders everything on your device. There is no telemetry, no analytics, and no network call on your behalf, and it works fully offline.