LessWrong's RSS feed includes all recently published articles by default, but it has a bunch of undocumented features available with query params.

Warning: The only officially supported options are view=frontpage, view=curated, and karmaThreshold. Other options may break in the future.

• You can request only posts above a certain karma (karmaThreshold), only with certain authors (userId), frontpage only (view=frontpage), curated-only (view=curated), and several other views.
  • Just the frontpage: https://www.lesswrong.com/feed.xml?view=frontpage
  • My posts: https://www.lesswrong.com/feed.xml?userId=piR3ZKGHEp6vqTo87^[1]
• Comments have RSS feeds (type=comment, view=postCommentsNew, postId, parentCommentId if you want only replies to a specific comment)
  • Comments on this post: https://www.lesswrong.com/feed.xml?type=comments&view=postCommentsNew&postId=dzF8vSdDtmWjCBBDr^[2]
• Quick takes / shortform have an RSS feed (view=shortform, view=topShortForm or view=shortformFrontpage)
  • Quick takes front page: https://www.lesswrong.com/feed.xml?type=comments&view=shortformFrontpage
  • My shortform: https://www.lesswrong.com/feed.xml?type=comments&view=shortform&userId=6jLdWqegNefgaabhr

There's also a full GraphQL API if you have needs beyond this, but the RSS feed is nice if you want it to work in a normal feed reader.

LessWrong RSS Feed Builder

Since there's a lot of options, I also built a tool to generate LessWrong RSS feed URLs.

Full Documentation

Note: This was generated by Claude after reading the source code for feed.xml and related utility code. Again, only view=frontpage, view=curated, and karmaThreshold are officially supported.

Query Parameters

Post Feed Views

Note: View names can use either camelCase (frontpageRss) or kebab-case (frontpage-rss).

Comment Feed Views

All comment views require type=comments. The limit is hardcoded to 50 results.

General

Per-Post (require postId)

These views exclude answers and answer-replies (filter answer: false, parentAnswerId: null).

Per-User

Shortform / Quick Takes

Per-Tag (require tagId)

sortBy Values

Views that support the sortBy parameter accept these values:

Karma Threshold Logic

The karmaThreshold parameter determines when posts appear in the feed based on when they reached certain karma levels. Posts have timestamps for when they exceeded various karma thresholds.

Input values are rounded to the nearest supported threshold:

The feed item's date is the later of:

1. The karma threshold date (when post reached the threshold)
2. The view-specific date (e.g., frontpageDate for frontpage feed)

This allows higher-threshold feeds to show older posts that recently became popular.

1. ^{^}

   I don't know where to get userIds from the UI, so I used the GraphQL API:

   $ curl -s -X POST https://www.lesswrong.com/graphql \
     -H 'Content-Type: application/json' \
     -d '{"query": "query { user(input: { selector: { slug: \"brendan-long\" } }) { result { _id } } }"}'
   {"data":{"user":{"result":{"_id":"piR3ZKGHEp6vqTo87"}}}}

2. ^{^}

   You can find postIds in the post URL, i.e. the postId for https://www.lesswrong.com/posts/ioZxrP7BhS5ArK59w/did-claude-3-opus-align-itself-via-gradient-hacking is ioZxrP7BhS5ArK59w.