Platform Guidelines

Character limits, hashtag best practices, and content formatting rules for each platform supported by SonetHub.

Detailed content guidelines, character limits, and best practices for each platform.

Instagram

  • Caption: max 2,200 characters. Optimal: 8-15 relevant hashtags (max 30)
  • Visual-first: captions complement the visual content
  • Engagement driven by saves and shares more than likes
  • Use line breaks for readability; emojis are welcome
  • CTA in captions boosts engagement ("save this for later", "double tap if...")
  • Stories, Reels, and carousels have different best practices
  • Put hashtags on their own line, separated from main text

Facebook

  • Optimal post length: 40-80 characters for engagement (longer acceptable)
  • Link sharing with preview cards performs well
  • Video (especially live) gets preferential algorithm treatment
  • Hashtags: 1-3 max, less critical than other platforms
  • Emotional and story-driven content performs best
  • Questions and polls drive comments
  • Write in short paragraphs (2-3 sentences) with blank lines

X (Twitter)

  • Tweet: max 280 characters
  • Thread support for longer narratives (label clearly: 1/5)
  • Hashtags: 1-2 per tweet max for best engagement
  • Timeliness and trending topics matter
  • Concise, punchy writing with strong hook
  • Media attachments (images, GIFs) significantly boost engagement
  • Mentions and replies build community

LinkedIn

  • Post: max 3,000 characters
  • Professional, thought-leadership tone
  • First 2-3 lines critical (shown before "...see more")
  • Hashtags: 3-5 industry-focused at end
  • Personal stories and lessons drive high engagement
  • Articles and document carousels (PDFs) perform well
  • Tagging people/companies increases reach
  • Value-first approach — avoid overly promotional

TikTok

  • Video-first — text-only NOT supported (must have video or photos)
  • Description: max 2,200 characters
  • Video: vertical 9:16, up to 10 minutes. First 3 seconds are critical
  • Photo carousel: 1-35 images with optional auto-added music
  • Trending sounds and music significantly boost reach
  • Hashtags: 3-5, mix trending and niche
  • Draft mode: tiktok_send_to_inbox=true sends video to creator's TikTok inbox as draft. Limited to 5/day. Video only.
  • Algorithm favors completion rate — shorter engaging videos outperform longer ones
  • Formats that work: behind-the-scenes, tutorials, day-in-the-life

Threads

  • Post: max 500 characters
  • Text-first — posts don't require media (unlike Instagram)
  • Conversational, authentic tone — less polished than LinkedIn, more thoughtful than X
  • Supports text, images, videos, carousels (up to 20 items)
  • Hashtags: 0-3 max, only if highly relevant
  • First line is the hook
  • Replies and conversations drive engagement more than likes
  • Longer-form thoughts (mini-essays, hot takes) perform well

Pinterest

  • Pin title: max 100 characters. Description: max 500 characters. Alt text: max 500 characters
  • Board selection required for every pin
  • Image or video required — no text-only pins. Optimal ratio: 2:3 (1000×1500px)
  • Link-driven platform — always include a destination URL
  • Uses keywords for search, NOT hashtags. 2-5 relevant keywords naturally in description
  • No comments API, no DMs API, no search API — publish + analytics only
  • Multiple images become separate pins (no native carousel)
  • Pins have months-long lifespan (vs hours/days on other platforms)
  • Best for: recipes, DIY, fashion, home decor, travel, infographics, tutorials

YouTube

Shorts

  • Vertical 9:16, up to 60 seconds. Title max 100 characters
  • Auto-tagged with #Shorts by YouTube
  • Published via the "Short Video / Reel" format in Compose or publish_reel tool

Long-form Videos

  • Any aspect ratio, any duration. Title max 100 characters, description max 5,000 characters
  • Category selection (People & Blogs, Education, Science & Technology, etc.)
  • Privacy: Public, Unlisted, or Private
  • Custom thumbnail: 1280×720 recommended (requires verified YouTube channel)
  • Published via the "Video" format in Compose or publish_post with youtube_video_type='long'

General

  • Per-workspace daily upload cap enforced (same quota for Shorts and long-form)
  • Analytics: views, watch time, avg view duration, subscriber changes, traffic sources, demographics (age/gender)
  • Comments manageable via API
  • Videos cannot be edited after publishing — delete and re-upload instead