OPML Outliner

A single-page HTML outliner for creating and editing OPML files, including OPML subscription lists and OPML inclusion files — no build step, no server, no dependencies. Open the outliner file and start outlining.

It extends Dave Winer’s HTML outliner (a compact, single-page version of his Drummer app) with some OPML 2.0 features it originally left out: attaching feed attributes to nodes, and linking one OPML file into another.

Usage

Go to this link in any modern browser — that’s it. Everything runs client-side.

• Create a new OPML file: Just start typing. Export with Export OPML.
• Create a subscription list: click + Add feed, paste a feed URL, and repeat. Export with Export OPML.
• Compose files: click + Add include, paste the URL of another .opml file, then click the node’s bullet to expand it in place.
• Edit attributes: click the 🧳 icon on a row (or the Inspect button) to open the inspector.
• View any OPML file: open outliner.html?url=https://example.com/list.opml.

Features

• Outlining — keyboard-driven editing (Enter, Tab/Shift-Tab, Alt-↑/↓), collapse/expand, hoist, drag-to-reorder, and localStorage persistence.
• Subscription lists — an Add feed command turns a node into an RSS feed (type="rss" + xmlUrl), with a best-effort read of the feed to fill in title, htmlUrl, description, language, and version.
• Inclusion — an Add include command creates a type="include" node whose url points to another OPML file, so you can compose one file out of many. type="link" nodes are supported too.
• In-place transclusion — expand an include node (or a link to a .opml file) to view the referenced OPML inline, read-only. Transcluded content is a live view — it is never written into your file on export or save.
• Attribute inspector ("🧳 suitcase") — view and edit any node’s OPML attributes: labeled fields for known feed/inclusion attributes, plus a generic list for anything custom.
• Lossless OPML — import and export preserve every attribute, so files round-trip without dropping data. Compatible with files from Drummer and Frontier.
• Type badges on rows, an export validation nudge for feeds/includes missing their required attribute, and a read-only URL viewer (outliner.html?url=…) for opening any public OPML file.

Enjoy!

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