A Ruby gem that downloads a public Reddit post and converts it — along with all its comments — to Markdown.

• Posts only. The gem only works with individual post URLs (e.g. reddit.com/r/subreddit/comments/…). Passing a subreddit listing, a user profile, a search results page, or any other Reddit URL will raise a NotAPostError.
• Public posts only. The gem makes unauthenticated requests to Reddit’s public JSON API. Posts that require you to be logged in — age-gated content, posts in private subreddits, quarantined communities — will not be accessible.

Add to your Gemfile:

gem "reddit_post_to_markdown"

Or install directly:

gem install reddit_post_to_markdown

require "reddit_post_to_markdown"

markdown = RedditPostToMarkdown.convert("https://www.reddit.com/r/ruby/comments/abc123/some_title/")
puts markdown

markdown = RedditPostToMarkdown.convert(url, include_comments: false)

Pass a filters: hash to suppress comments that match any of the criteria below. A matching comment has its body replaced with the :message string rather than being removed entirely, so the thread structure is preserved.

markdown = RedditPostToMarkdown.convert(
  url,
  filters: {
    keywords:    ["spam", "buy now"],     # case-insensitive substring match
    authors:     ["AutoModerator"],       # exact username to exclude comments from (case-sensitive)
    min_upvotes: 5,                       # comments below this score are replaced
    regexes:     [/\bfree\b/i],           # Array of Regexp objects
    message:     "[ removed by filter ]"  # optional; see default below
  }
)

All keys are optional. The default replacement message is "REMOVED DUE TO CUSTOM FILTER(S)".

Filters are applied in this order: keywords → authors → min_upvotes → regexes. The first match wins.

Note: [deleted] comments are handled before filtering and always render as Comment deleted by user regardless of filter settings.

markdown = RedditPostToMarkdown.convert(
  url,
  include_comments: true,
  filters: { min_upvotes: 10 }
)

begin
  markdown = RedditPostToMarkdown.convert(url)
rescue RedditPostToMarkdown::NotAPostError => e
  warn "Not a post URL: #{e.message}"
rescue RedditPostToMarkdown::FetchError => e
  warn "Could not reach Reddit: #{e.message}"
rescue RedditPostToMarkdown::InvalidResponseError => e
  warn "Unexpected response: #{e.message}"
end

The generated Markdown matches the output of the reddit-markdown tool. A post renders as:

**r/subreddit** | Posted by u/author ⬆️ 1k _( 2022-01-01 00:00:00 )_

## Post Title

Original post: [https://…](https://…)

> Post body text, if any,
> is block-quoted here.

💬 ~ 42 replies

---

  *  **[top_level_commenter](https://www.reddit.com/user/top_level_commenter)** ⬆️ 50 _( 2022-01-01 00:10:00 )_

  	Top-level comment body.

  	*  **[reply_author](https://www.reddit.com/user/reply_author)** ⬆️ 12 _( 2022-01-01 00:20:00 )_

  		Nested reply, indented one tab deeper per level.

u/username mentions in comment bodies are converted to links.

MIT License. See LICENSE.

This gem is a Ruby port of the core post-download and Markdown-rendering functionality from reddit-markdown by Chau Duy Phan Vu. The output format, comment structure, color indicators, HTML entity handling, and filter logic are all derived from that project. Only the features relevant to converting a single post URL to a Markdown string have been ported; scheduling, authentication, file I/O, archiving, search, and other functionality from the original tool are intentionally omitted.

Some additional functionality relative to this core behavior has been, and will be added.