Platform Limits

This comprehensive guide documents the limits for all 10 social media platforms supported by PostPost. Understanding these limits is essential for building reliable integrations with the PostPost API.

Last Updated: March 2026

Overview

When building applications with the PostPost API, it is critical to understand that API limits often differ from native app limits. Social media platforms impose different restrictions depending on whether content is posted through their official apps, web interfaces, or third-party APIs.

Note: PostPost defines 11 platform keys internally (including Pinterest), but only 10 platforms are actively supported. Pinterest is listed for reference and is planned for a future release.

PostPost validates your content against these API-specific limits before scheduling. This guide covers:

Character limits for captions and descriptions
Image formats, sizes, and counts
Video duration, file size, and format requirements
Platform-specific requirements (which platforms require media)
Rate limits for posting frequency
Common API error messages and validation codes

Key Principle: Always design your integration around the API limits documented here, not the limits you observe when posting manually through native apps.

Critical API vs Native App Differences

The following table highlights the most significant differences between API and native app limits. These are the restrictions most likely to cause unexpected failures if you assume native app behavior.

Platform	API Restriction	Native App Allows	Impact
Twitter/X	2 min video max	2:20 (140s) video	Videos over 2 min will fail
Instagram	3 min Reels, 10 carousel items, JPEG only	15-20 min Reels, 20 items, PNG/GIF	PNG images will be rejected
TikTok	10 min video, 2,200 char captions	60 min video, 4,000 chars	Long captions truncated or rejected
Facebook	45 min video, 2 GB files	240 min video, 4 GB files	Large files will fail
LinkedIn	500 MB video	5 GB video	Videos over 500 MB will fail
Telegram	50 MB files (Bot API)	4 GB (user clients)	Large media uploads will fail

Character Limits

All platforms have character limits for text content. Some platforms have different limits for premium accounts or specific content types.

Platform	Standard Limit	Premium/Special	Notes
Twitter/X	280 characters	25,000 (Premium)	Threading supported for long content
Instagram	2,200 characters	-	First 125 chars visible before "more"
Threads	500 characters	10,000 (text attachment)	Threading supported; max 5 links per post
TikTok	2,200 characters (API)	4,000 (native app)	API enforces stricter limit
LinkedIn	3,000 characters	-	First 210 chars visible before "see more"
YouTube	100 (title) / 5,000 (description)	-	First 150 chars of description visible
Facebook	63,206 characters	-	Posts under 80 chars get 66% more engagement
Mastodon	500 characters	Instance-configurable	Some instances allow 5,000+
Bluesky	300 characters	-	Links count toward the limit in PostPost
Telegram	4,096 characters	1,024 (bot caption)	Bots limited to 1,024 for media captions
Pinterest	100 (title) / 800 (description)	500 (ads)	Not currently supported -- planned for a future release

Character Limit Best Practices

Design for the lowest common denominator when cross-posting. If posting to Twitter and Threads, keep content under 280 characters.
Use threading for long-form content on Twitter/X and Threads rather than truncating.
Front-load important information since most platforms truncate visible content with a "see more" link.

Image Limits

Image requirements vary significantly across platforms. Pay particular attention to the Instagram API restriction requiring JPEG format only.

Platform	Max Size	Max Count	Supported Formats
Twitter/X	5 MB	4	JPEG, PNG, GIF, WebP
Instagram	8 MB	10 (API carousel)	JPEG only (API)
Threads	8 MB	10	JPEG, PNG
TikTok	-	0	Video only platform
LinkedIn	5 MB	10 (multi-image)	JPEG, PNG, GIF
YouTube	-	0	Video only for uploads
Facebook	10 MB	10	JPEG, PNG, GIF, BMP, TIFF
Mastodon	16 MB	4	JPEG, PNG, GIF, WebP (instance-configurable)
Bluesky	1 MB	4	JPEG, PNG, WebP (max 2000x2000 px)
Telegram	10 MB	10	JPEG, PNG, GIF, WebP, BMP
Pinterest	20 MB	5 (carousel)	JPEG, PNG, TIFF, BMP, GIF, WebP

Critical Image Notes

Issue	Platform	Details
JPEG Only	Instagram	The Instagram API only accepts JPEG format. PNG and GIF uploads will fail with an error.
Carousel Limit	Instagram	API carousels are limited to 10 items (native app allows 20).
No Mixed Media	Instagram	Cannot mix images and videos in the same carousel via API.
Strict Size Limit	Bluesky	Hard 1 MB limit. Compress images to 80-85% JPEG quality before uploading.
No Organic Carousels	LinkedIn	Organic swipeable carousels are NOT supported via API (only sponsored content).

Server-Side Upload Limits

The multipart upload endpoint enforces server-side limits in addition to platform-specific limits:

Maximum 4 files per upload request
Maximum 512 MB per file

Presigned URL uploads bypass these server-side limits -- use presigned URLs for larger files.

Image Processing in PostPost

PostPost automatically handles some image conversions:

WebP images are automatically converted to JPEG for platforms that do not support WebP natively.
Oversized images are validated and rejected with a clear error message.

Video Limits

Video restrictions through APIs are often significantly more restrictive than native apps. This is one of the most common sources of failed posts.

Platform	Max Duration	Max Size	Supported Formats
Twitter/X (API)	2 min (120s)	512 MB	MP4, MOV
Instagram Reels (API)	3 minutes (180s)	300 MB	MP4, MOV
Instagram Carousel	60s per video	300 MB	MP4, MOV
Threads	5 min	500 MB	MP4, MOV
TikTok (API)	10 min	4 GB	MP4, MOV, WebM
LinkedIn (API)	30 min	500 MB	MP4
YouTube	12 hours	256 GB	MP4, MOV, AVI, WebM
Facebook (API)	45 min	2 GB	MP4, MOV
Facebook Reels (API)	90 seconds	1 GB	MP4, MOV
Mastodon	No limit*	~99 MB	MP4, MOV, WebM
Bluesky	3 min	100 MB	MP4
Telegram (Bot API)	No limit	50 MB	MP4, MOV, AVI, MKV, WebM
Pinterest	15 min	1 GB	MP4, MOV

*Mastodon video duration is limited only by file size (~99 MB default).

Platform-Specific Video Restrictions

Instagram API

Restriction	API Limit	Native App Limit
Reels duration	3 minutes (180s)	15-20 minutes
Image format	JPEG only	PNG, GIF also supported
Carousel items	10	20
Account type	Business accounts only	Creator accounts supported
Features	No shopping tags, branded content, filters, or music	Full feature set

TikTok API

Restriction	API Limit	Native App Limit
Video duration	10 minutes	60 minutes
Caption length	2,200 characters	4,000 characters
Daily posts	15-20 posts/day	Higher limit
Unaudited apps	Can only post PRIVATE videos	Public posting

Facebook API

Restriction	API Limit	Native App Limit
Video duration	45 minutes	240 minutes
File size	2 GB	4 GB
Reels posting	Pages only (not personal profiles)	Both supported
Reels rate limit	30 Reels per day per Page	Higher limit

LinkedIn API

Restriction	API Limit	Native App Limit
Video file size	500 MB	5 GB
Video duration	30 minutes	15 minutes (API allows more)
Carousels	No organic carousels (sponsored only)	Supported
Media mixing	Cannot mix images with videos or documents	Supported

Telegram Bot API

Restriction	Standard Bot API	Local Bot API Server
File size limit	50 MB	2 GB
Caption length	1,024 characters	1,024 characters
Premium features	Not available to bots	Not available to bots

Bluesky API

Restriction	Details
Daily limit	25 videos OR 10 GB per day
Size tiers	Videos under 60s: 50 MB max. Videos 60s-3min: 100 MB max
Prerequisites	Email verification required before video uploads

Platform Requirements

Different platforms have different requirements for media. Some platforms are text-only capable, while others require media for every post.

Platform	Requires Media	Requires Video	Supports Text-Only	Supports Threading
Twitter/X	No	No	Yes	Yes
Instagram	Yes	No	No	No
Threads	No	No	Yes	Yes
TikTok	Yes	Yes	No	No
LinkedIn	No	No	Yes	No
YouTube	Yes	Yes	No	No
Facebook	No	No	Yes	No
Mastodon	No	No	Yes	No
Bluesky	No	No	Yes	No
Telegram	No	No	Yes	No
Pinterest	Yes	No	No	No

Media Requirement Notes

TikTok and YouTube are video-only platforms. You cannot post images or text-only content.
Instagram requires at least one image or video with every post.
Pinterest is listed for reference but is not currently supported in PostPost. Support is planned for a future release.
Threading allows long content to be automatically split into multiple connected posts (Twitter/X and Threads only).

Rate Limits

Each platform enforces its own posting rate limits. Exceeding these limits will result in failed posts or temporary restrictions on your account.

Platform	Posting Limit	Notes
Instagram	50 posts/24hr (some report 25)	Carousels count as 1 post
Threads	250 posts/24hr	1,000 replies/24hr
TikTok	15-20 posts/day	2 videos/minute max
LinkedIn	Not published	Approximately 200+ calls/hour based on user count
Facebook	30 Reels/day/page	General rate formula: 200 x users/hour
Bluesky	25 videos/day	3,000 requests/5 min
Mastodon	30 media uploads/30 min	300 requests/5 min per account
Telegram	30 messages/second	20 messages/minute per group
Pinterest	15-25 pins/day recommended	Not currently supported

Rate Limit Best Practices

Space out posts rather than bulk-posting at the same time.
Implement exponential backoff when you receive rate limit errors.
Track your posting frequency per platform to stay within limits.
Use PostPost's built-in rate limiting which automatically queues and distributes posts.

Common API Error Messages

When posts fail, the platform returns specific error messages. Understanding these errors helps you diagnose and fix issues quickly.

Instagram Errors

Error	Meaning	Resolution
`(#10) The user is not an Instagram Business`	Creator accounts not supported	Use a Business account, not a Creator account
`Error 2207010`	Caption limit exceeded	Reduce caption to under 2,200 characters
`Error 2207004`	Image exceeds 8 MB	Compress image to under 8 MB
`Error 9, Subcode 2207042`	Publishing rate limit reached	Wait before posting again

TikTok Errors

Error	Meaning	Resolution
`spam_risk_too_many_posts`	Daily post limit reached	Wait 24 hours before posting again
`duration_check_failed`	Video must be 3s-10min	Adjust video duration
`unaudited_client_can_only_post_to_private_accounts`	App needs TikTok review	Submit app for TikTok audit

Twitter/X Errors

Error	Meaning	Resolution
`This user is not allowed to post a video longer than 2 minutes`	API video duration limit	Trim video to under 2 minutes

Facebook Errors

Error	Meaning	Resolution
`Error 1363026`	Video exceeds 40 min duration	Trim video to under 45 minutes
`Error 1363023`	File size exceeds 2 GB	Compress video to under 2 GB
`Error 1363128`	Reels duration outside 3-90 second range	Adjust Reel to 3-90 seconds

LinkedIn Errors

Error	Meaning	Resolution
`MEDIA_ASSET_PROCESSING_FAILED`	File too large or unsupported format	Check file size (<500 MB) and format (MP4)
`Error 429`	Rate limit exceeded	Wait and retry with backoff

Telegram Errors

Error	Meaning	Resolution
`MEDIA_CAPTION_TOO_LONG`	Caption exceeds 1024 chars (bots)	Reduce caption length
`Bad Request: file is too big`	File exceeds 50 MB	Compress file to under 50 MB

Bluesky Errors

Error	Meaning	Resolution
`429 Too Many Requests`	Rate limit exceeded	Wait and retry
Video job state `JOB_STATE_FAILED`	Video processing failed	Check video format and size

Validation Error Codes

The PostPost validation system returns standardized error codes when content does not meet platform requirements. Use these codes to provide clear feedback to users.

Content Errors

Error Code	Description
`CONTENT_TOO_LONG`	Content exceeds the platform's character limit
`CONTENT_TOO_SHORT`	Content is below the minimum required length
`CONTENT_REQUIRED`	Text content is required for this platform
`CONTENT_OR_MEDIA_REQUIRED`	Either text content or media is required

Media Errors

Error Code	Description
`MEDIA_REQUIRED`	Platform requires at least one media file
`MEDIA_SIZE_EXCEEDED`	File size exceeds the platform limit
`MEDIA_COUNT_EXCEEDED`	Too many media files attached
`MEDIA_TYPE_NOT_SUPPORTED`	File format is not supported by the platform
`MEDIA_DIMENSIONS_INVALID`	Image dimensions are outside the allowed range

Video Errors

Error Code	Description
`VIDEO_REQUIRED`	Platform requires a video (TikTok, YouTube)
`VIDEO_DURATION_EXCEEDED`	Video duration exceeds the platform limit
`VIDEO_DURATION_TOO_SHORT`	Video is shorter than the minimum required duration
`VIDEO_NOT_SUPPORTED`	Platform does not support video content
`IMAGES_NOT_SUPPORTED`	Platform is video-only and does not accept images

Platform Errors

Error Code	Description
`PLATFORM_NOT_SUPPORTED`	Unknown or unsupported platform identifier
`PLATFORM_SETTING_REQUIRED`	A required platform-specific setting is missing
`PLATFORM_SETTING_INVALID`	A platform-specific setting has an invalid value

Sources

Official platform documentation used to compile these limits:

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