A cover image, also called a thumbnail, is the still image people see before playing a video. For example, a clear frame showing the finished recipe can help viewers understand a cooking video before opening it.
Open the destination's Preview → Settings, then choose the video's cover control. Review each destination separately: a cover supported for a feed video may not be supported for a Story or Reel.
Choose a cover
- Upload cover image is the primary choice wherever the destination supports custom image uploads. Use an image that accurately represents the video.
- Suggested snapshots offers still images taken from an uploaded video. Choose one to use it as the cover; these are real video frames, not newly invented images. Suggestions require a Postly-uploaded video below 512 MB.
- Choose another frame expands the manual frame selector where the destination accepts a frame position. It stays collapsed to leave more room for editing.
For frame-only destinations, the picker shows suggested snapshots and Choose another frame, with no upload button. Choosing a snapshot sends its original position in the video to the platform; the snapshot image itself is not uploaded as a replacement cover. Postly keeps the platform's required units, such as milliseconds for TikTok.
Existing selected covers remain attached to the draft. Choosing a different cover does not replace the original video. A platform can crop a cover differently in its feed, profile grid, or video player.
Platform differences
| Destination | What to expect |
|---|---|
| Instagram Reels and videos shared to the feed | Custom cover images and video-frame positions are supported by the publishing API. Instagram gives an uploaded cover priority when both are supplied. |
| Instagram Stories | A separate custom video cover is not a publishing option. |
| Facebook Page feed videos | A custom image can be applied to the accepted video as its preferred thumbnail. Permissions and processing must allow the update. |
| Facebook Reels | Reels use a separate publishing API. Do not assume feed-video thumbnail options apply to Reels. Postly does not offer an unverified custom-image option for this format. |
| LinkedIn native videos | Upload a JPEG or PNG cover with the video. Use an image below 2 MB. |
| YouTube videos | Upload a custom thumbnail or use a suggested snapshot. YouTube channel eligibility and format restrictions still apply; Shorts may display covers differently. |
| Pinterest videos | Custom cover images and supported video-frame positions depend on the video publishing format. |
| TikTok direct video publishing | The API accepts a video-frame timestamp rather than a separate uploaded cover image. Choose a snapshot or expand the manual frame selector. |
| Telegram videos and video albums | A custom image is sent as the video's cover. This is different from Telegram's small technical thumbnail, which the platform can regenerate. |
| X, Threads and Bluesky videos | Postly does not offer a separate video-cover choice for these publishing APIs. Their own apps may have different editing options; a link-preview image is not a video-cover upload. |
| Other destinations | Only use the options shown for that destination and format. Link-preview images, blog featured images, and video covers are different publishing settings. |
If a cover cannot be applied
If the platform has already accepted the video, do not publish it again just to repair its cover. Check the publication result and update the cover on the platform if needed. Postly can report a settings warning separately from the successful publication.
API terminology
The media field thumbnail remains the canonical field for existing integrations. Cover-image aliases such as cover_image, cover_url, and cover_image_url are recognized as the same media choice. The canonical frame offset thumbnail_offset is in milliseconds. A cover selection does not make a destination support a feature its publishing API does not provide.
References
- Instagram publishing examples from Meta
- Facebook Video Thumbnails API
- LinkedIn Videos API
- YouTube thumbnail uploads
- TikTok content publishing
- Threads video publishing examples from Meta
- X media metadata API
For upload preparation, see media upload limits and video validation.