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Reddit API — Write Operations

Submit posts and comments to Reddit via the Reddit API (OAuth2)

Instructions

Reddit API — Write Operations

Use the Reddit API to submit posts and comments on Reddit. All write operations require OAuth2 authentication with a script or web app, and the account must have sufficient karma and age for the target subreddit.

Prerequisites

  • Completed reddit-api-read fundamental (OAuth2 app created, token obtained)
  • Reddit account with positive karma history in target subreddits
  • Understanding of each subreddit's posting rules (many subreddits have minimum karma/age requirements)

Submit a Text Post

POST https://oauth.reddit.com/api/submit
Content-Type: application/x-www-form-urlencoded
Authorization: Bearer TOKEN

kind=self&sr=SUBREDDIT&title=POST_TITLE&text=POST_BODY&sendreplies=true

Parameters:

  • kind: self (text post) or link (link post)
  • sr: Subreddit name (without r/ prefix)
  • title: Post title (max 300 characters)
  • text: Post body in Markdown format
  • url: For link posts, the URL to submit
  • flair_id: Optional flair ID (get available flairs via GET /r/SUBREDDIT/api/link_flair_v2)
  • sendreplies: true to receive reply notifications

Response: {"json": {"data": {"name": "t3_POST_ID", "url": "https://reddit.com/r/..."}}}

Submit a Comment

POST https://oauth.reddit.com/api/comment
Content-Type: application/x-www-form-urlencoded
Authorization: Bearer TOKEN

thing_id=t3_POST_ID&text=COMMENT_TEXT

Parameters:

  • thing_id: The fullname of the post (t3_ID) or parent comment (t1_ID) to reply to
  • text: Comment body in Markdown format

Response: {"json": {"data": {"things": [{"data": {"id": "COMMENT_ID", ...}}]}}}

Add UTM Parameters to Links

When including links in posts or comments, always append UTM parameters for tracking:

https://yoursite.com/resource?utm_source=reddit&utm_medium=community&utm_campaign=reddit-niche-communities&utm_content=r_SUBREDDIT_NAME

This enables PostHog to attribute referral traffic to specific subreddits and posts.

Important Constraints

  1. Rate limits: Reddit enforces posting rate limits per account. New accounts may be limited to 1 post per 10 minutes. Established accounts get higher limits.
  2. Subreddit rules: Many subreddits auto-remove posts from accounts younger than X days or with karma below Y. Check GET /r/SUBREDDIT/about/rules and review the sidebar.
  3. Self-promotion rules: Reddit's site-wide guideline is the "10% rule" — no more than 10% of your submissions should be self-promotional. Most subreddits enforce stricter limits.
  4. Shadowbans: If your posts consistently get removed or receive zero engagement, your account may be shadowbanned. Check at https://www.reddit.com/api/v1/me to verify your account status.
  5. Markdown formatting: Reddit uses its own Markdown flavor. Line breaks require two newlines. Links are [text](url). Code blocks use triple backticks or 4-space indentation.

Python (PRAW) Alternative

import praw

reddit = praw.Reddit(
    client_id="CLIENT_ID",
    client_secret="CLIENT_SECRET",
    user_agent="YourApp/1.0 by YourRedditUsername",
    username="REDDIT_USERNAME",
    password="REDDIT_PASSWORD"
)

# Submit a text post
subreddit = reddit.subreddit("SUBREDDIT")
submission = subreddit.submit(
    title="How we solved X problem",
    selftext="Here is our approach to solving X...\n\n[Full writeup](https://yoursite.com/blog/x?utm_source=reddit&utm_medium=community)"
)

# Submit a comment on a post
submission = reddit.submission(id="POST_ID")
comment = submission.reply("Great question! Here is what worked for us...")

# Reply to a comment
comment = reddit.comment(id="COMMENT_ID")
reply = comment.reply("Adding to this point...")

Error Handling

  • RATELIMIT: Response includes ratelimit field with seconds to wait. Back off accordingly.
  • 403 Forbidden: Account lacks posting permissions in this subreddit. Build karma first.
  • 400 Bad Request: Invalid parameters. Check subreddit allows your post type (some are link-only or text-only).
  • SUBREDDIT_NOTALLOWED: Your account doesn't meet the subreddit's age/karma requirements.

Anti-Spam Best Practices

  • Space out posts: maximum 2-3 posts per day across all subreddits
  • Vary your content — don't post the same text across multiple subreddits
  • Engage in comments on other people's posts before posting your own content
  • Build genuine karma by being helpful in discussions unrelated to your product
  • Never use multiple accounts to upvote your own posts