Use this page to make each post fit the social platform you choose.
Most settings go inside platform_options. To use one cover on every platform, add thumbnail_url to the video in media. To use a different cover for each platform, add thumbnail_url to that platform’s options. comments_under_post goes in the main post request. See Create Post for the full request.
Facebook
Facebook supports feed posts, Stories, and Reels.
Facebook post type
Set platform_options.facebook.post_type to feed, story, or reel.
- A feed post can have text, a link, up to 10 images, or one video.
- A Story can have one image or one video.
- A Reel needs one 9:16 MP4 or MOV video. It must be 3 to 90 seconds long and at least 540 by 960 pixels.
Facebook message
Use platform_options.facebook.message to write text just for Facebook. If you leave it out, Mallary uses the main post message.
Facebook custom video thumbnail
Add thumbnail_url to a Facebook feed video in media, or use platform_options.facebook.thumbnail_url for a Facebook-only cover. Use a JPG or PNG file stored by Mallary. The thumbnail can be up to 10 MB. Facebook chooses the cover for Reels.
Use comments_under_post to add up to three comments under a feed post or Reel. Facebook Stories do not use first comments.
Instagram
Instagram supports feed posts, Stories, Reels, and carousels.
Instagram post type
Set platform_options.instagram.post_type to feed, story, reel, or carousel.
- A feed post has one image or one video.
- A Story has one image or one video.
- A Reel has one video.
- A carousel has 2 to 10 images and videos.
Instagram caption
Use platform_options.instagram.message to write a caption just for Instagram. If you leave it out, Mallary uses the main post message. Story text must be part of the image or video.
Instagram Reel profile feed
Use platform_options.instagram.shareToFeed with a Reel. Leave it out or set it to true to show the Reel in both your profile feed and Reels tab. Set it to false to show the Reel only in the Reels tab. This option only works when post_type is reel.
Instagram Trial Reels
Add platform_options.instagram.trialParams to publish a Trial Reel. Instagram shows a Trial Reel to people who do not follow you first. This option only works when post_type is reel. Do not add shareToFeed to the same request.
Instagram Trial Reel graduation
Choose how the Trial Reel can become a regular Reel:
- Use
MANUAL when you want to make that choice later in the Instagram app.
- Use
SS_PERFORMANCE when you want Instagram to share it with followers if it performs well.
Instagram paid partnership label
Set platform_options.instagram.isPaidPartnership to true to show Instagram’s Paid partnership label. You can use it with a feed post, Reel, or carousel. It does not work with Stories.
This feature needs an Instagram account connected through Facebook Login. If the account uses Instagram Login, Mallary stops the post before it is queued and tells you to reconnect.
Instagram branded content sponsors
Use platform_options.instagram.brandedContentSponsors to tag up to two sponsors. Each item can be an Instagram username, with or without @, or a numeric Instagram user ID. Adding a sponsor also turns on the Paid partnership label.
Mallary looks up each username when it publishes the post. The sponsor must be a public Business or Creator account. If Instagram cannot find the account, Mallary returns an error that names the sponsor.
If the brand has already approved the partnership, Instagram can show Paid partnership with @brand right away. If not, Instagram shows the plain label and sends the brand an approval request.
Instagram custom video cover
Add thumbnail_url to a feed video or Reel in media, or use platform_options.instagram.thumbnail_url for an Instagram-only cover. Use an image stored by Mallary. A tall cover works best for a Reel.
Use comments_under_post to add up to three comments under a feed post, Reel, or carousel. Stories do not use first comments.
LinkedIn
LinkedIn supports text posts, one image or GIF, or one MP4 video. Videos can be up to 1 GB (1,073,741,824 bytes) and 3 seconds to 30 minutes long. Do not mix images and video.
Upload the video to Mallary, then add its URL to media. No LinkedIn video option is needed. The dashboard, REST API, MCP, and CLI use the same publishing flow.
LinkedIn message
Use platform_options.linkedin.message to write text just for LinkedIn. If you leave it out, Mallary uses the main post message.
LinkedIn choose who posts
Use platform_options.linkedin.author_urn to choose a person or company page. You can also save this choice when you connect LinkedIn in Mallary.
Threads
Threads supports text, image, video, and carousel posts.
Threads post type
Set platform_options.threads.post_type to text, image, video, or carousel. You can also leave it out and let Mallary choose from your media.
Threads message
Use platform_options.threads.message to write text just for Threads. If you leave it out, Mallary uses the main post message.
Threads first replies
Use comments_under_post to add up to three replies under your new Threads post.
YouTube
YouTube supports Shorts and long-form videos.
YouTube video type
Set platform_options.youtube.post_type to shorts or regular. You can also leave it out and let Mallary choose from the video shape and length.
YouTube title and description
Use platform_options.youtube.title for the video title. Use platform_options.youtube.message for the description. If you leave the title out, Mallary uses the first line of the message.
Use platform_options.youtube.tags to add words that describe the video. Send the tags as a list of text values.
Each tag can use up to 100 characters. All tags together can use up to 500 characters. YouTube counts the commas between tags. It also counts two extra quote marks around a tag that has spaces. Mallary removes exact duplicate tags and checks these limits before posting.
YouTube visibility
Set platform_options.youtube.visibility to public, unlisted, or private. The default is public.
YouTube custom thumbnail
Add thumbnail_url to a YouTube video in media, or use platform_options.youtube.thumbnail_url for a YouTube-only cover. Use a JPG or PNG file stored by Mallary. The image can be up to 2 MB.
For a regular video, use a 16:9 image. YouTube can show it as the custom thumbnail.
For a Short, YouTube may accept and store the image but still show a frame from the video. Mallary returns a warning because the YouTube API cannot tell us which cover viewers will see. Use YouTube Studio to add a custom image, or use the YouTube app to choose a frame.
YouTube playlist
Set platform_options.youtube.playlist_id to add the new video to an existing playlist. The playlist must belong to the connected YouTube channel. Mallary checks the playlist before it uploads the video.
Mallary can add to an existing playlist. It does not create a new playlist from a name.
YouTube category and audience
Use platform_options.youtube.categoryId to choose a YouTube category. Use platform_options.youtube.madeForKids to say if the video is made for kids.
YouTube AI content disclosure
Set platform_options.youtube.containsSyntheticMedia to true when a video contains realistic AI-generated or altered content that could look real. This includes making a real person appear to say or do something they did not, changing a real event or place, or creating a realistic scene that did not happen. YouTube may show a disclosure label on the video.
This setting is optional and applies only to the YouTube video in that post. Mallary does not turn it on just because you use an AI assistant.
Use comments_under_post to add up to three comments when YouTube allows comments on the video.
TikTok
TikTok supports videos and photo carousels.
TikTok post type
Set platform_options.tiktok.post_type to video or photo. You can also leave it out and let Mallary choose from your media.
TikTok how it publishes
TikTok uses DIRECT_POST by default, so Mallary publishes the post for you. Set platform_options.tiktok.post_mode to MEDIA_UPLOAD only when you want to send the post to your TikTok inbox and finish it in the TikTok app. An inbox upload stays action_required until you add the final TikTok post URL.
TikTok upload source
For videos, set platform_options.tiktok.source to FILE_UPLOAD or PULL_FROM_URL. A pulled file must already be stored by Mallary. Photo posts use PULL_FROM_URL.
TikTok caption and details
Use these fields for TikTok text:
platform_options.tiktok.message sets the TikTok caption.platform_options.tiktok.title sets the TikTok title.platform_options.tiktok.description sets the photo post description.
TikTok privacy and sharing
Use platform_options.tiktok.privacy_level to choose who can see a direct post. Use disable_comment, disable_duet, and disable_stitch to control how people can use the post.
TikTok cover
Use platform_options.tiktok.video_cover_timestamp_ms to pick a frame from a video. Use platform_options.tiktok.photo_cover_index to pick the cover photo in a carousel.
TikTok music
Set platform_options.tiktok.auto_add_music to true to let TikTok add music to a direct photo post. To pick a trending sound, use MEDIA_UPLOAD and choose the sound in the TikTok app.
TikTok content labels
Use brand_content_toggle, brand_organic_toggle, and is_aigc when the post needs a brand, business, or AI-made label.
Pinterest
Pinterest supports image Pins and video Pins.
Pinterest pin type
Set platform_options.pinterest.post_type to image or video. You can also leave it out and let Mallary choose from your media.
Pinterest board
Use platform_options.pinterest.boardId to choose the board that gets the Pin. If you leave it out, Mallary can use the board saved with the connection.
Pinterest title and description
Use platform_options.pinterest.title for the Pin title. Use platform_options.pinterest.message for the description. Pinterest allows 800 characters in a description. Mallary shortens longer descriptions to fit, so the Pin can still publish.
Pinterest destination link
Use platform_options.pinterest.link to send people to a web page when they click the Pin.
Pinterest alt text
Use platform_options.pinterest.alt_text to add a short image description for people who use screen readers.
Reddit
Reddit supports text, link, and image posts.
Reddit subreddit
Use platform_options.reddit.subreddit or subredditName to choose the community that gets the post.
Reddit post type
Set platform_options.reddit.post_type to text, link, or image. You can also leave it out and let Mallary choose from your media.
Reddit text
Use platform_options.reddit.message to write text just for Reddit. Mallary uses this text for the Reddit title and post text where needed.
Bluesky
Bluesky supports text, image, and video posts.
Bluesky message
Use platform_options.bluesky.message to write a message just for Bluesky. A Bluesky post can have up to 300 characters.
Bluesky post languages
Use platform_options.bluesky.languages to add up to three language codes, such as en or es. You can also use langs.
Bluesky image alt text
Add alt_text to each image in media. This tells people who use screen readers what the image shows.
Bluesky first replies
Use comments_under_post to add up to three replies under your new Bluesky post.
X supports text, image, video, and GIF posts.
X message
Use platform_options.x.message to write text just for X. platform_options.twitter.message also works for older requests.
Add up to four images, one video, or one GIF to media. Mallary picks the post type from the media. Do not mix images and video.
X video limits depend on the connected X account. Standard accounts can use videos up to 20 minutes and 8 GB. Eligible Premium or verified accounts can use videos up to 125 minutes and 16 GB. Mallary checks the account when a video is above the standard limits. Mallary’s current upload endpoint accepts files up to 5 GB.
X first replies
Use comments_under_post to add up to three replies under your new X post. Last modified on September 8, 2026
