Schedule and automate Reddit posts with Zernio API - Text posts, link posts, image posts, subreddit targeting, flair selection, and gallery posts

Quick Reference

Property	Value
Title limit	300 characters (required, cannot edit after)
Body text	40,000 characters
Images per post	1 (single), multiple (gallery)
Videos per post	Not supported via API
Image formats	JPEG, PNG, GIF
Image max size	20 MB
Post types	Text, Link, Image, Gallery
Scheduling	Yes
Inbox (DMs)	Yes (add-on, text only)
Inbox (Comments)	Yes (add-on)
Analytics	No

Reddit is fundamentally different from every other platform. Each subreddit (community) is independently moderated with its own rules. There is no universal set of rules. What works in one subreddit will get you banned in another.

Before posting to any subreddit via API, you must:

Check if the subreddit allows your post type (text, link, or image)
Check if flair is required (many subreddits auto-remove posts without flair)
Check if the subreddit allows third-party/automated posting
Check karma and account age requirements

More than half of all Reddit posts via Zernio fail. Almost every failure is preventable by reading the target subreddit's rules first.

Additional warnings:

Title is permanent -- Reddit titles cannot be edited after posting
New accounts are restricted -- Low karma and new account age will block most subreddits
No video uploads -- Reddit's API does not support video uploads for third-party apps
Each subreddit has unique, independent rules -- Always check before posting

Quick Start

Post to Reddit in under 60 seconds:

const { post } = await zernio.posts.createPost({
  content: "What is your favorite programming language and why?\n\nI have been using Python for years but considering learning Rust.",
  platforms: [
    {
      platform: 'reddit',
      accountId: 'YOUR_ACCOUNT_ID',
      platformSpecificData: {
        subreddit: 'learnprogramming'
      }
    }
  ],
  publishNow: true
});
console.log('Posted to Reddit!', post._id);

result = client.posts.create(
    content="What is your favorite programming language and why?\n\nI have been using Python for years but considering learning Rust.",
    platforms=[
        {
            "platform": "reddit",
            "accountId": "YOUR_ACCOUNT_ID",
            "platformSpecificData": {
                "subreddit": "learnprogramming"
            }
        }
    ],
    publish_now=True
)
post = result.post
print(f"Posted to Reddit! {post['_id']}")

curl -X POST https://zernio.com/api/v1/posts \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "content": "What is your favorite programming language and why?\n\nI have been using Python for years but considering learning Rust.",
    "platforms": [
      {
        "platform": "reddit",
        "accountId": "YOUR_ACCOUNT_ID",
        "platformSpecificData": {
          "subreddit": "learnprogramming"
        }
      }
    ],
    "publishNow": true
  }'

Content Types

Text Post (Self Post)

A text post with a title and optional body. This is the default post type when no media or URL is provided. The first line of content becomes the title, and the rest becomes the body. Reddit Markdown is supported in the body.

const { post } = await zernio.posts.createPost({
  content: "Tips for learning a new programming language\n\nHere are some things that worked for me:\n\n1. Start with the official tutorial\n2. Build a small project immediately\n3. Read other people's code\n4. Contribute to open source",
  platforms: [
    {
      platform: 'reddit',
      accountId: 'YOUR_ACCOUNT_ID',
      platformSpecificData: {
        subreddit: 'learnprogramming'
      }
    }
  ],
  publishNow: true
});
console.log('Text post created!', post._id);

result = client.posts.create(
    content="Tips for learning a new programming language\n\nHere are some things that worked for me:\n\n1. Start with the official tutorial\n2. Build a small project immediately\n3. Read other people's code\n4. Contribute to open source",
    platforms=[
        {
            "platform": "reddit",
            "accountId": "YOUR_ACCOUNT_ID",
            "platformSpecificData": {
                "subreddit": "learnprogramming"
            }
        }
    ],
    publish_now=True
)
post = result.post
print(f"Text post created! {post['_id']}")

curl -X POST https://zernio.com/api/v1/posts \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "content": "Tips for learning a new programming language\n\nHere are some things that worked for me:\n\n1. Start with the official tutorial\n2. Build a small project immediately\n3. Read other people'\''s code\n4. Contribute to open source",
    "platforms": [
      {
        "platform": "reddit",
        "accountId": "YOUR_ACCOUNT_ID",
        "platformSpecificData": {
          "subreddit": "learnprogramming"
        }
      }
    ],
    "publishNow": true
  }'

Link Post

Share an external URL. When platformSpecificData.url is provided, Reddit creates a link post instead of a text post. The content becomes the post title.

const { post } = await zernio.posts.createPost({
  content: 'Interesting article about modern API design patterns',
  platforms: [
    {
      platform: 'reddit',
      accountId: 'YOUR_ACCOUNT_ID',
      platformSpecificData: {
        subreddit: 'programming',
        url: 'https://example.com/api-design-article'
      }
    }
  ],
  publishNow: true
});
console.log('Link post created!', post._id);

result = client.posts.create(
    content="Interesting article about modern API design patterns",
    platforms=[
        {
            "platform": "reddit",
            "accountId": "YOUR_ACCOUNT_ID",
            "platformSpecificData": {
                "subreddit": "programming",
                "url": "https://example.com/api-design-article"
            }
        }
    ],
    publish_now=True
)
post = result.post
print(f"Link post created! {post['_id']}")

curl -X POST https://zernio.com/api/v1/posts \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "content": "Interesting article about modern API design patterns",
    "platforms": [
      {
        "platform": "reddit",
        "accountId": "YOUR_ACCOUNT_ID",
        "platformSpecificData": {
          "subreddit": "programming",
          "url": "https://example.com/api-design-article"
        }
      }
    ],
    "publishNow": true
  }'

Image Post

Attach a single image to a post. The content becomes the post title.

const { post } = await zernio.posts.createPost({
  content: 'Check out this view from my hike!',
  mediaItems: [
    { type: 'image', url: 'https://example.com/hiking-photo.jpg' }
  ],
  platforms: [
    {
      platform: 'reddit',
      accountId: 'YOUR_ACCOUNT_ID',
      platformSpecificData: {
        subreddit: 'hiking'
      }
    }
  ],
  publishNow: true
});
console.log('Image post created!', post._id);

result = client.posts.create(
    content="Check out this view from my hike!",
    media_items=[
        {"type": "image", "url": "https://example.com/hiking-photo.jpg"}
    ],
    platforms=[
        {
            "platform": "reddit",
            "accountId": "YOUR_ACCOUNT_ID",
            "platformSpecificData": {
                "subreddit": "hiking"
            }
        }
    ],
    publish_now=True
)
post = result.post
print(f"Image post created! {post['_id']}")

curl -X POST https://zernio.com/api/v1/posts \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "content": "Check out this view from my hike!",
    "mediaItems": [
      {"type": "image", "url": "https://example.com/hiking-photo.jpg"}
    ],
    "platforms": [
      {
        "platform": "reddit",
        "accountId": "YOUR_ACCOUNT_ID",
        "platformSpecificData": {
          "subreddit": "hiking"
        }
      }
    ],
    "publishNow": true
  }'

Gallery Post

Attach multiple images to create a gallery post. Not all subreddits support galleries.

const { post } = await zernio.posts.createPost({
  content: 'My weekend woodworking project - start to finish',
  mediaItems: [
    { type: 'image', url: 'https://example.com/step1.jpg' },
    { type: 'image', url: 'https://example.com/step2.jpg' },
    { type: 'image', url: 'https://example.com/step3.jpg' },
    { type: 'image', url: 'https://example.com/finished.jpg' }
  ],
  platforms: [
    {
      platform: 'reddit',
      accountId: 'YOUR_ACCOUNT_ID',
      platformSpecificData: {
        subreddit: 'woodworking'
      }
    }
  ],
  publishNow: true
});
console.log('Gallery post created!', post._id);

result = client.posts.create(
    content="My weekend woodworking project - start to finish",
    media_items=[
        {"type": "image", "url": "https://example.com/step1.jpg"},
        {"type": "image", "url": "https://example.com/step2.jpg"},
        {"type": "image", "url": "https://example.com/step3.jpg"},
        {"type": "image", "url": "https://example.com/finished.jpg"}
    ],
    platforms=[
        {
            "platform": "reddit",
            "accountId": "YOUR_ACCOUNT_ID",
            "platformSpecificData": {
                "subreddit": "woodworking"
            }
        }
    ],
    publish_now=True
)
post = result.post
print(f"Gallery post created! {post['_id']}")

curl -X POST https://zernio.com/api/v1/posts \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "content": "My weekend woodworking project - start to finish",
    "mediaItems": [
      {"type": "image", "url": "https://example.com/step1.jpg"},
      {"type": "image", "url": "https://example.com/step2.jpg"},
      {"type": "image", "url": "https://example.com/step3.jpg"},
      {"type": "image", "url": "https://example.com/finished.jpg"}
    ],
    "platforms": [
      {
        "platform": "reddit",
        "accountId": "YOUR_ACCOUNT_ID",
        "platformSpecificData": {
          "subreddit": "woodworking"
        }
      }
    ],
    "publishNow": true
  }'

Media Requirements

Images

Property	Requirement
Max images	1 per post (single), multiple (gallery)
Formats	JPEG, PNG, GIF
Max file size	20 MB
Recommended	1200 x 628 px

Aspect Ratios

Reddit is flexible with aspect ratios:

Ratio	Use Case
16:9	Standard landscape
4:3	Classic format
1:1	Square images
9:16	Mobile screenshots

GIFs

Static display until clicked
Max 20 MB
May convert to video format internally
Keep under 10 MB for better performance

Platform-Specific Fields

All fields go inside platformSpecificData on the Reddit platform entry.

Field	Type	Required	Description
`subreddit`	string	Effectively yes	Target subreddit (without `r/` prefix). Falls back to account default if omitted. Aliases: `subredditName`, `sr`
`title`	string	Yes (by Reddit)	Post title, max 300 characters. Cannot be edited after posting. If omitted, first line of `content` is used.
`url`	string	No	External URL for link posts. If provided, creates a link post instead of a text post.
`flairId`	string	Varies	Reddit flair ID. Many subreddits require this. Get flairs via `GET /v1/accounts/{accountId}/reddit-flairs?subreddit=NAME`. Aliases: `redditFlairId`
`forceSelf`	boolean	No	Force text/self post even when media is attached.

Subreddit Selection

Posts are submitted to the subreddit configured on the connected Reddit account by default. To post to a specific subreddit, set platformSpecificData.subreddit (without the r/ prefix).

Post Flairs

Some subreddits require a post flair. First, list available flairs for a subreddit:

const { flairs } = await zernio.accounts.getRedditFlairs('YOUR_ACCOUNT_ID', {
  subreddit: 'socialmedia'
});
console.log(flairs);

result = client.accounts.get_reddit_flairs(
    "YOUR_ACCOUNT_ID",
    subreddit="socialmedia"
)
print(result.flairs)

curl -X GET "https://zernio.com/api/v1/accounts/YOUR_ACCOUNT_ID/reddit-flairs?subreddit=socialmedia" \
  -H "Authorization: Bearer YOUR_API_KEY"

Then, create a post with flairId:

const { post } = await zernio.posts.createPost({
  content: 'What is your favorite programming language and why?',
  platforms: [
    {
      platform: 'reddit',
      accountId: 'YOUR_ACCOUNT_ID',
      platformSpecificData: {
        subreddit: 'socialmedia',
        flairId: 'a1b2c3d4-e5f6-7890-abcd-ef1234567890'
      }
    }
  ],
  publishNow: true
});
console.log('Posted to Reddit!', post._id);

result = client.posts.create(
    content="What is your favorite programming language and why?",
    platforms=[
        {
            "platform": "reddit",
            "accountId": "YOUR_ACCOUNT_ID",
            "platformSpecificData": {
                "subreddit": "socialmedia",
                "flairId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890"
            }
        }
    ],
    publish_now=True
)
post = result.post
print(f"Posted to Reddit! {post['_id']}")

curl -X POST https://zernio.com/api/v1/posts \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "content": "What is your favorite programming language and why?",
    "platforms": [
      {
        "platform": "reddit",
        "accountId": "YOUR_ACCOUNT_ID",
        "platformSpecificData": {
          "subreddit": "socialmedia",
          "flairId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890"
        }
      }
    ],
    "publishNow": true
  }'

If a subreddit requires a flair and you do not provide flairId, Zernio will attempt to use the first available flair as a fallback.

Formatting

Reddit supports Markdown in text post bodies:

# Heading
## Subheading
**Bold text**
*Italic text*
~~Strikethrough~~
- Bullet points
1. Numbered lists
[Link text](https://example.com)
> Block quotes
`inline code`

Auto-Retry Behavior

Zernio automatically retries failed Reddit posts in certain situations:

Link post in text-only subreddit -- If a link post fails with a NO_LINKS error (subreddit only allows text posts), Zernio auto-retries as a text/self post with the URL included in the body.
Missing required flair -- If a subreddit requires flair but none was provided, Zernio tries to use the first available flair automatically.

Analytics

Requires Analytics add-on

Available metrics via the Analytics API:

Metric	Available
Likes (upvotes)	✅
Comments	✅

Reddit does not provide impressions, reach, shares, clicks, or view counts through its API.

const analytics = await zernio.analytics.getAnalytics({
  platform: 'reddit',
  fromDate: '2024-01-01',
  toDate: '2024-01-31'
});
console.log(analytics.posts);

analytics = client.analytics.get(
    platform="reddit",
    from_date="2024-01-01",
    to_date="2024-01-31"
)
print(analytics["posts"])

curl "https://zernio.com/api/v1/analytics?platform=reddit&fromDate=2024-01-01&toDate=2024-01-31" \
  -H "Authorization: Bearer YOUR_API_KEY"

What You Can't Do

These features are not available through Reddit's API:

Upload videos (Reddit API limitation for third-party apps)
Create polls
Crosspost to other subreddits
Edit post title after creation
Add post to collections
Create live chat threads
Award/give gold to posts
See upvote/downvote counts (score only)

If you need to post videos to Reddit, upload to a video hosting service (YouTube, Imgur, etc.) and create a link post with the video URL.

Common Errors

Reddit has a 53.9% failure rate across Zernio's platform (4,785 failures out of 8,877 attempts). Here are the most frequent errors and how to fix them:

Error	What it means	How to fix
"SUBREDDIT_NOTALLOWED: only trusted members"	Subreddit restricts who can post	Join the community, build karma, or choose a different subreddit
"NO_SELFS: doesn't allow text posts"	Subreddit only accepts link or image posts	Provide a URL via `platformSpecificData.url` or attach an image
"SUBMIT_VALIDATION_FLAIR_REQUIRED"	Subreddit requires flair on all posts	Fetch flairs with `GET /v1/accounts/{accountId}/reddit-flairs?subreddit=NAME` and provide the correct `flairId`
"SUBREDDIT_NOEXIST"	Typo in subreddit name or subreddit is private	Check spelling, do not include the `r/` prefix
"AI-generated content not allowed"	Subreddit bans AI-generated content	Write original content or choose a different subreddit
"Reddit removed the post"	Moderators or AutoMod removed the post after submission	Check subreddit rules, ensure content complies
"Reddit requires a subreddit"	No subreddit was specified and no default is set	Always provide `platformSpecificData.subreddit`
"Rate limited"	Reddit's rate limit was hit	Space posts further apart. New accounts are limited to around 10 posts per day.

Inbox

Requires Inbox add-on — Build: +$10/mo · Accelerate: +$50/unit · Unlimited: +$1,000/mo

Reddit supports DMs (private messages) and comments.

Direct Messages

Feature	Supported
List conversations	✅
Fetch messages	✅
Send text messages	✅
Send attachments	❌ (API limitation)
Archive/unarchive	✅

Comments

Feature	Supported
List comments on posts	✅
Reply to comments	✅
Delete comments	✅
Upvote/downvote	✅
Remove vote	✅

Limitations

No DM attachments - Reddit's API does not support media in private messages
Subreddit required - When replying to comments, you must provide the subreddit parameter

See Messages and Comments API Reference for endpoint details.

Connect Reddit Account - OAuth flow
Create Post - Post creation and scheduling
Upload Media - Image uploads
Reddit Search - Search Reddit content
Reddit Subreddits - List subscribed subreddits
Reddit Flairs - Get available flairs for a subreddit
Messages and Comments - Inbox API