Social Media API: Post Images and Video in 2026

Q: Can one REST API post to Instagram, TikTok and X at the same time?

Yes. Name all three in the platforms array of a single POST /v1/posts request with a shared med_ id. Creator OS applies each platform’s rules, including Instagram Reel covers, TikTok consent flags and X video length limits. Any network that isn’t connected comes back in missing_platforms and the rest still publish.

Q: How do you upload a video through a social media post API?

Send the file to POST /v1/media once and keep the returned med_ id. Reference that id in the media array of your post request, on as many platforms as you like. From the CLI the same step is creatoros media:upload clip.mp4 .

Use a social media api to post images and videos to social media by uploading the file once, then naming the platforms you want in one request. Creator OS gives you a single REST endpoint: send the video or image to /v1/media, get back a med_ id, and reuse that id in POST /v1/posts for Instagram, TikTok, YouTube, X and the rest.

your app
   |
   |  POST /v1/media  (file or URL)
   v
med_abc123  <-- upload once, reuse everywhere
   |
   |  POST /v1/posts
   |    content, platforms, media, schedule_at
   v
Creator OS  -->  Instagram Reels
            -->  TikTok video
            -->  YouTube Short
            -->  X video post
            -->  Threads / Facebook / LinkedIn

One upload, one post call, many networks.

What Is a Social Media API for Post Creation?

A social media post API is a programmatic way to publish content to a network without opening its app. You send a request with a caption and media, and the service handles the network’s rules, tokens and upload flow for you.

Every network has its own rules underneath. Instagram Reels need a business or creator account. TikTok needs privacy and consent flags before a video goes up. YouTube wants a title, a visibility setting and a category. X caps standard video length at about 2 minutes 20 seconds. An API for post creation takes your one payload and translates it per network, so you write the request once.

Creator OS is that layer. It exposes a REST API, a CLI (@creatoros/cli), a hosted MCP server and a Claude Code plugin on top of the same workspace, so a script, an agent and the web app all drive the same accounts. If you want the wider picture of how one interface spans every network, the post on one API for all social networks covers it.

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Why One API Instead of 11 Platform Integrations

Every platform you add is another OAuth flow, another token refresh, another set of media rules to learn and re-learn. That work multiplies fast.

Consider what you maintain when you integrate each network directly. Instagram and Facebook live under Meta with their own app review. TikTok has its own developer app and audit. YouTube and Google share a consent screen. X, LinkedIn and Threads each ship their own scopes and limits. You keep credentials, retry logic and error shapes for each one, and you test all of them again whenever a network changes something.

Concern	Integrating each network	One post API
Auth	Per-platform OAuth and refresh	One `cos_live_` key per workspace
Media	Re-upload per network, per format	Upload once, reuse the `med_` id
Rules	Learn Reels, Shorts, TikTok flags separately	Applied per platform from one request
Errors	Different shape per vendor	One `{ error: { code, message, status } }`
Partial failure	Your code decides what to do	Unconnected networks return in `missing_platforms`
Scoping	You enforce it yourself	Key is pinned to one workspace

That last point matters for agencies. A key is tied to one set of socials. An agent holding one client’s key cannot post to another client’s accounts. You build the guard rail once by issuing one key per workspace.

How the Creator OS REST API Posts Images and Videos to Instagram, TikTok and X

A post is two calls: upload the media, then create the post that references it. The same med_ id works on every platform you name.

Here is a worked example. You have a 30 second vertical clip and you want it on Instagram as a Reel, on TikTok as a video, and on X.

# 1. Upload the file once
curl -X POST https://YOUR_BASE/v1/media \
  -H "Authorization: Bearer cos_live_..." \
  -F "file=@clip.mp4"
# returns { "id": "med_abc123", ... }

# 2. Post it everywhere
curl -X POST https://YOUR_BASE/v1/posts \
  -H "Authorization: Bearer cos_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "content": "Three edits that fix a flat clip",
    "platforms": ["instagram","tiktok","twitter"],
    "media": ["med_abc123"],
    "schedule_at": "2026-03-04T18:00:00Z",
    "timezone": "America/Toronto"
  }'

Find the base URL in the docs at https://www.creatoros.ca/docs; never hardcode one you guessed. The same request works from the CLI if you prefer a shell:

creatoros media:upload clip.mp4
creatoros posts:create \
  --text "Three edits that fix a flat clip" \
  --platforms instagram,tiktok,twitter \
  --media med_abc123 \
  --scheduledAt 2026-03-04T18:00:00Z \
  --timezone America/Toronto

When you need per-network settings, switch to the advanced form. Platforms become objects with their own options, TikTok settings move into a top-level tiktok object, and account_ids narrows a post to specific accounts. Creator OS fills the required TikTok flags for you in the simple form: privacy_level, allow_comment, allow_duet, allow_stitch, and the preview and consent confirmations. Send draft: true and the TikTok video lands in the creator’s inbox to finish in the app.

For Instagram, a Reel cover comes from instagramThumbnail or a frame via thumbOffset. The API can’t attach trending audio, so bake sound into the file before upload. For X, add replyToTweetId or quoteTweetId and X keeps the thread together. If you are building toward Instagram specifically, how to let an AI agent post to Instagram walks through the same flow from an agent’s side.

What Platforms Does the All-in-One Social Media API Cover?

Creator OS posts to Instagram, TikTok, YouTube, X, Threads, Facebook, LinkedIn, Reddit, Discord and Slack, and handles WhatsApp messages rather than posts.

Each network keeps its own options, and the API applies them from your single payload. A few specifics worth knowing before you build:

YouTube: long-form and Shorts. Vertical short videos become Shorts automatically. firstComment is posted and pinned. Custom thumbnails work on long-form only.
Threads: 500 characters per post, up to 250 posts per 24 hours, multi-post threads via threadItems, and topic_tag between 1 and 50 characters.
Reddit: text, link, image galleries and video. A reddit object carries subreddit, title, flairId and flags.
Discord and Slack: each connected channel is its own account, and a post goes to every connected channel unless you narrow it with account_ids.

Networks you name but haven’t connected come back in missing_platforms, and the rest still publish. That is deliberate: one dead token shouldn’t stop the other nine posts. The full parameter list lives in the post options docs.

Can You Post Images and Videos With a Single Upload Endpoint?

Yes. POST /v1/media uploads a file one time and returns a med_ id you can reference on every platform and in every later post.

The id is an opaque typed token, like post_, cmt_ and conv_ elsewhere in the API. Treat it as a handle, not something to parse. Once you have it, drop it into the media array of any post request. You can mix ids and plain URLs in the same array, so a hosted asset you already have can go straight in.

A practical pattern for a content team: upload the master clip and the still frames at the start of the week, store the ids in your database, and let scheduled posts reference them. Nothing is re-uploaded when a post is retried or rescheduled. If a post fails, creatoros posts:retry post_... pushes the same media again without a fresh upload.

Two limits come from the networks, not the API. Instagram can’t attach trending audio through any API, so the sound has to be in the file. Discord video posts are not listed among the supported options, so send video to Discord as a file attachment rather than assuming it will play inline.

How to Authenticate and Send Your First Post Request

Authenticate with a Creator OS API key that starts cos_live_. Create one in Settings, under API keys, inside the workspace you want to post to.

Sign up and connect the social accounts you plan to post to.
Open Settings, then API keys, and create a key. Make a read-only key if the integration only needs to read.
Send every request with Authorization: Bearer cos_live_....
Upload media with POST /v1/media and keep the med_ id.
Create the post with POST /v1/posts, naming platforms and the media id.

Errors always come back in the same shape: { "error": { "code": ..., "message": ..., "status": ... } }. Write one handler and it covers every endpoint. Read-only keys can be created the same way, and the API refuses writes from them, which makes them safe to hand to a reporting tool or a read-only AI connection.

For an AI agent, the hosted MCP server at https://mcp.creatoros.ca/mcp does the same work without you writing HTTP at all. Add it as a connector, sign in, and pick read-only or read & write per connection. Tool names include create_post, upload_media_from_url, get_post_analytics and get_best_time_to_post. Destructive tools like delete post are marked so the AI app asks first. Authentication details are in the authentication docs.

One API vs n8n and Zapier for Social Post Automation

Automation platforms connect apps with triggers and actions. Creator OS is the posting layer those workflows can call, and it also runs the post itself.

n8n and Zapier are general workflow tools. You build a flow that fires on an event and calls a service. If that service is Creator OS, the flow inherits one upload endpoint and one post endpoint across the networks, instead of a separate node per platform. You can picture the difference as where the platform rules live. In a per-network flow, your workflow carries the TikTok flags and the YouTube title rules. With Creator OS, you send a caption and media, and the rules are applied server side.

The same logic applies to agents. A Claude Code user can install the Creator OS plugin and get the MCP server, campaign builder skills and a publish guard that asks Proceed or Cancel before anything is published or deleted:

/plugin marketplace add kevinbadi/creatoros-claude-plugin
/plugin install creatoros@creatoros
/plugin configure creatoros@creatoros

If you are weighing the two approaches directly, Creator OS vs n8n for social media workflows and Creator OS vs Zapier for social media go deeper. Kevin builds these on camera; watch the walkthroughs on the KevBuildsApps YouTube channel, and the launch video shows the agent and plugin in action.

FAQ: API to Post Images and Videos to Social Media

What is the best API to post images and videos to social media?

Pick an API that covers the networks you actually publish to and applies each network’s media rules for you. Creator OS posts images and video to 11 platforms plus Skool from one REST API, with one upload endpoint and one error shape. You can compare its request shapes against your own requirements in the docs at https://www.creatoros.ca/docs.

Can one REST API post to Instagram, TikTok and X at the same time?

Yes. Name all three in the platforms array of a single POST /v1/posts request with a shared med_ id. Creator OS applies each platform’s rules, including Instagram Reel covers, TikTok consent flags and X video length limits. Any network that isn’t connected comes back in missing_platforms and the rest still publish.

How do you upload a video through a social media post API?

Send the file to POST /v1/media once and keep the returned med_ id. Reference that id in the media array of your post request, on as many platforms as you like. From the CLI the same step is creatoros media:upload clip.mp4.

Is there a free all-in-one social media API for developers?

Creator OS starts new subscribers on a free trial and you can cancel anytime. API keys, the MCP server, the CLI and the agent skills are included in every plan, including the Creator plan at $14.99/month or $59.99/year. See the sign-up page for current trial terms.

How long does it take to integrate the Creator OS social post API?

Most of the work is the two calls: upload media, then create the post. If you already have OAuth and a scheduler, you are mainly swapping your per-network post calls for one request and one error handler. Working from the docs and a single test workspace keeps the first post short.

Get Started With One API for Social Media

One upload, one post request, eleven networks. That is the whole idea. Connect your accounts, create an API key in Settings, and send your first POST /v1/media. Then wire the med_ id into POST /v1/posts and name every platform you want in the same request.

If you would rather watch it happen first, the KevBuildsApps channel has the build videos, and the launch video is the fastest tour of the API, CLI and agent working together.

Start at https://www.creatoros.ca/sign-up. Creator OS plans start at $14.99/month for 11 platforms plus Skool, with the API, the MCP server and the CLI included.

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