OPML to Haddock Converter
FileFlip converts OPML to Haddock entirely inside your browser, using Pandoc compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert an OPML file to Haddock?#
- Drop your OPML file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to Haddock and the conversion starts on its own. FileFlip downloads 65.8 MB of WebAssembly the first time and nothing after that, then runs Pandoc on your own machine.
- Save the Haddock file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting OPML to Haddock lose quality?#
Not in the sense of pixels or samples. Converting OPML to Haddock rebuilds the file in Haddock's own model rather than re-encoding it, so everything Haddock can represent comes through exactly and anything it cannot has to be dropped. Expect the words to come through exactly and the page breaks to move.
Is it safe to convert OPML files online?#
Yes, because nothing is uploaded. FileFlip converts OPML files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What OPML to Haddock actually does to the file#
Converting OPML to Haddock runs on Pandoc, downloads 65.8 MB of WebAssembly the first time and nothing after that, rebuilds the file in the target's own model, keeps selectable text and page layout.
| Engine | Pandoc |
|---|---|
| Conversion path | One step: OPML → Haddock |
| Downloaded to your browser | 65.8 MB, once, then cached by your browser |
| Quality | Rebuilt in the target's model |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| Selectable text | Kept | Carried through into the converted file. |
| Page layout | Kept | Carried through into the converted file. |
What is an OPML file?#
An OPML file is an XML document made of nested outline elements, most often used to move a list of RSS and Atom feed subscriptions from one feed reader to another.
Use OPML to move a list of feed subscriptions between RSS readers, or to export a hierarchical outline from an outliner app.
Convert OPML into a document format like HTML or Markdown when the outline itself, not the feed subscriptions, needs to be read as a document.
What is a Haddock file?#
A Haddock file holds documentation written in Haddock markup, the comment syntax Haskell's own documentation generator reads out of source files to build a module's API reference.
Write Haddock markup directly in Haskell source comments so `cabal haddock` can generate the package's API documentation.
Convert Haddock markup to Markdown when the same text needs to appear in a README or a project website outside the generated API docs.
OPML to Haddock questions people ask#
What is an OPML file?
An OPML file is an XML document that stores a nested outline, most commonly a list of RSS and Atom feed subscriptions. Feed readers use it to export a subscription list from one app and import it into another.
What do I use an OPML file for?
The main use of an OPML file today is moving feed subscriptions between RSS readers like Feedly, Inoreader or NetNewsWire, so switching apps does not mean resubscribing to every feed by hand. UserLand Software originally designed OPML for general hierarchical outlines, not just feeds.
Can I edit an OPML file by hand?
Yes, an OPML file is plain XML text, so it opens and edits in any text editor. Each subscription or outline entry appears as an outline element with attributes like a title and, for feeds, the feed's URL.
What is a .haddock file?
A .haddock file holds text written in Haddock markup, the comment syntax Haskell's documentation generator reads. In practice this markup normally lives inside `-- |` and `-- ^` comments in a .hs source file rather than a standalone file, so a .haddock file usually appears when that text has been extracted or converted on its own.