Secrets of the LessWrong RSS Feed

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

Parameter	Type	Description
`type`	string	Set to `comments` for comment feeds, otherwise returns posts
`view`	string	Feed type/view (see views below). Defaults to `rss`
`karmaThreshold`	number	Minimum karma for posts to appear (see threshold logic below)
`filterSettings`	JSON	Advanced filtering (JSON-encoded object)
`postId`	string	Filter comments to a specific post
`tagId`	string	For `tagRelevance` post view or tag comment views
`userId`	string	Filter by author user ID
`parentCommentId`	string	For `commentReplies` view—replies to a specific comment
`parentAnswerId`	string	For `repliesToAnswer` view—replies to a specific answer
`topLevelCommentId`	string	For `repliesToCommentThread` view—full thread under a comment
`forumEventId`	string	For `forumEventComments` view
`sortBy`	string	Sort mode for views that support it (see per-view notes)

Post Feed Views

View	Description	Sort Order
`rss` (default)	All newest posts	`postedAt` descending
`frontpageRss`	Frontpage posts only	`frontpageDate` descending
`curatedRss`	Curated posts only	`curatedDate` descending
`communityRss`	Non-frontpage posts with karma > 2	`postedAt` descending
`metaRss`	Meta posts only	`postedAt` descending
`tagRelevance`	Posts by tag (requires `tagId` param)	Tag relevance score

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

View	Description	Sort
`rss` (default)	Recent comments with positive score (alias for `recentComments`)	`postedAt` desc
`recentComments`	Recent comments with positive score	`postedAt` desc
`allRecentComments`	All recent comments including neutral/negative score	`postedAt` desc
`commentReplies`	Replies to a specific comment (requires `parentCommentId`)	`postedAt` desc
`moderatorComments`	Comments posted with a moderator hat	`postedAt` desc

Per-Post (require `postId`)

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

View	Description	Sort
`postCommentsNew`	Comments on a post, newest first	`postedAt` desc
`postCommentsOld`	Comments on a post, oldest first	`postedAt` asc
`postCommentsTop`	Comments on a post, highest karma first	`baseScore` desc
`postCommentsBest`	Comments on a post, best first	`baseScore` desc
`postCommentsMagic`	Comments on a post, magic/Wilson sort	`score` desc
`postCommentsRecentReplies`	Comments on a post, by recent subthread activity	`lastSubthreadActivity` desc
`postsItemComments`	Recent non-deleted comments on a post	`postedAt` desc
`questionAnswers`	Answers to a question post (supports `sortBy`)	`baseScore` desc
`answersAndReplies`	Answers and their replies (supports `sortBy`)	`baseScore` desc
`debateResponses`	Debate responses on a post	`postedAt` asc
`recentDebateResponses`	Recent debate responses on a post	`postedAt` desc

Per-User

View	Description	Sort
`profileComments`	Comments by a user (supports `sortBy`)	`postedAt` desc
`profileRecentComments`	(Deprecated) Recent comments by a user	`postedAt` desc

Shortform / Quick Takes

View	Description	Sort
`shortform`	Top-level shortform comments	`lastSubthreadActivity` desc
`topShortform`	Top shortform by score (supports `before`/`after`)	`baseScore` desc
`shortformFrontpage`	Frontpage shortform (recent, filtered by quality)	`score` desc

Per-Tag (require `tagId`)

View	Description	Sort
`tagDiscussionComments`	Discussion comments on a tag	default
`tagSubforumComments`	Subforum comments for a tag (supports `sortBy`)	`lastSubthreadActivity` desc

`sortBy` Values

Views that support the sortBy parameter accept these values:

Value	Sort Order
`top`	`baseScore` descending
`new` / `newest`	`postedAt` descending
`old` / `oldest`	`postedAt` ascending
`magic`	`score` descending
`recentComments`	`lastSubthreadActivity` descending

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:

Input Range	Actual Threshold	Date Field Used
< 16 (or not set)	2	`scoreExceeded2Date`
16-36	30	`scoreExceeded30Date`
37-59	45	`scoreExceeded45Date`
60-99	75	`scoreExceeded75Date`
100-161	125	`scoreExceeded125Date`
>= 162	200	`scoreExceeded200Date`

The feed item’s date is the later of:

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

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

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″}}}}

^
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.