How to Schedule Instagram Posts via API

Schedule Instagram posts programmatically using the SocialRails API. This guide covers image requirements, caption limits, media uploads, code examples, and best practices for automated Instagram posting.

Character Limits

• Caption: 2,200 characters
• Hashtags: Maximum 30 per post (20 recommended)
• Bio: 150 characters
• Comments: 2,200 characters

Supported Content Types

API Example

# Upload media first
curl -X POST https://socialrails.com/api/v1/media/upload \
  -H "Authorization: Bearer sr_live_YOUR_KEY" \
  -F "file=@my-photo.jpg"
 
# Then schedule the post with the media
curl -X POST https://socialrails.com/api/v1/posts \
  -H "Authorization: Bearer sr_live_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "content": "Launching something new today!\n\nAfter months of building, we are excited to share our public API with the world.\n\n#launch #api #socialrails #buildinpublic",
    "platform": "instagram",
    "media": ["MEDIA_KEY_FROM_UPLOAD"],
    "scheduled_for": "2026-03-05T12:00:00Z"
  }'

Image Requirements

• Aspect ratios: Square (1:1), Landscape (1.91:1), Portrait (4:5)
• Minimum resolution: 320px on shortest side
• Maximum resolution: 1080px wide
• File size: Up to 8MB for images
• Format: JPEG and PNG (JPEG recommended for smaller file size)

Best Practices

• Optimal posting times: Monday-Friday, 11am-1pm and 7-9pm
• Hashtag strategy: Mix popular (100K+ posts) and niche (1K-50K posts) hashtags
• Caption length: First 125 characters appear above the fold, front-load the hook
• Line breaks: Use empty lines between paragraphs for readability
• CTA: End captions with a question or call-to-action to increase comments
• Post consistently, the algorithm favors regular posting schedules

Important Notes

• Instagram requires a Business or Creator account for API posting
• Posts must include an image or video, text-only posts are not supported
• The Instagram API publishes posts immediately or at the scheduled time, there's no "draft" state on Instagram itself