Personal profile and Company Page posts. Text, image, carousel (document), video. The dwell-time-driven algorithm and what it rewards.
LinkedIn posts go through the official Marketing Developer Platform API. We support both personal profile posts and Company Page posts — pick which one when you connect.
What you can post
| Type | Supported | Notes |
|---|---|---|
| Text post | ✓ | Up to 3,000 characters |
| Single image | ✓ | JPG / PNG / WebP, up to 5 MB |
| Carousel (Document) | ✓ | 2-9 PDF / image carousel |
| Video | ✓ | Up to 30 min, 5 GB max |
| Article | — | LinkedIn's long-form editor is gated to the web UI |
| Poll | — | API doesn't support poll creation |
Personal vs. Company Page
When you connect LinkedIn, the OAuth flow asks which page(s) you want to grant Post Mate access to. You can pick:
- Your personal profile
- Any Company Page where you have admin access
Each one shows up as a separate connection in Post Mate, so you can schedule one post to your personal profile and a different version to your Company Page from the same compose flow.
Caption rules
- Max length: 3,000 characters (personal); 700 (Company Page — yes, LinkedIn really capped the company version lower)
- @-mentions for users and companies; LinkedIn renders these as blue clickable links
- URL previews: if you include a URL, LinkedIn auto-generates a preview card from the page's Open Graph tags. The post gets ~30% less reach than the same post without the URL (LinkedIn punishes out-links). Workaround: put the URL in the first comment after the post publishes, or describe the link and let people DM for it.
Document carousels
These are LinkedIn's "PDF carousel" format — the swipeable post that dominates the feed in 2026. To create one in Post Mate:
- Upload either a PDF (2-9 pages) or multiple images. We auto-stitch images into a PDF if you upload them individually.
- Max file size 100 MB total.
- Cover thumbnail is the first page / first image.
LinkedIn rewards document carousels heavily because the swipe gesture counts as engagement. Our advice: 6-8 slides is the sweet spot — long enough for dwell time, short enough that people finish.
Video specs
- Format: MP4
- Codec: H.264
- Aspect ratio: 1:2.4 to 2.4:1 (1:1 and 16:9 are the practical defaults)
- Length: 3 seconds minimum, 30 minutes maximum
- File size: 5 GB max
Vertical video is now first-class on LinkedIn — they push it into the feed similarly to Reels.
Per-post settings we expose
- Visibility — Public, Connections only.
- Comments allowed — toggle. Off disables both comments and replies on the post.
What LinkedIn quietly punishes
We've covered the algorithm in detail on the blog. The short version of things to avoid for reach:
- External links in the body (~30% reach penalty)
- ALL CAPS shouting in headlines
- "Broetry" one-line-paragraph posts (now flagged)
- Spam-style hashtag stuffing (5+ hashtags)
- Mentioning the algorithm itself
Common rejection reasons
403 Forbidden— LinkedIn revoked the OAuth token. Usually because you changed your LinkedIn password or revoked Post Mate from your LinkedIn app permissions. Reconnect.Invalid URN— the personal profile / Company Page reference is stale. Reconnect to refresh.Member not found— an @-mention pointed at a user who's deleted or restricted their account. Remove the mention.