Post to social media from ChatGPT with Mellow Hub

Before you start

1. Create a free Mellow account at mellow.world.
2. Connect the accounts you want to post to in Accounts. You sign in to each network on its own page; ChatGPT can't do this step for you.
3. Publishing needs a Hub plan, from $19 a month. A new account starts with 7 days for $0 (card required), and a monthly plan's first month is 20% off. Connecting accounts, drafts and checks are free. See plans.

Add Mellow Hub to ChatGPT

These are the labels in OpenAI's developer mode guide. Menus move between releases; if a label differs, that guide shows the current screen.

1. Turn on developer mode. On Business, each admin or owner turns it on for themselves in Settings → Apps → Advanced settings → Developer mode. On Enterprise and Edu, an admin first allows it in Workspace settings → Permissions & Roles → Connected Data; then each allowed member turns it on in Settings → Apps → Advanced settings.
2. Go to Settings → Apps → Create. Admins can also use Workspace settings → Apps → Create.
3. Name the app Mellow Hub, enter https://www.mellow.world/mcp as the MCP server URL, and choose OAuth as the authentication.
4. Click Scan Tools. A Mellow window opens: sign in, then choose on Hub's consent screen which accounts ChatGPT may use, review or autopilot, a daily ceiling and how long the access lasts. Approve, and wait for the scan to finish.
5. Click Create. The app appears in Settings → Apps with a Dev label next to its name.
6. Open a new chat, pick Mellow Hub from the tools menu, and ask. ChatGPT may ask you to confirm before it takes an action.
7. To give it to your whole workspace, an admin publishes the draft from Workspace settings → Apps → Drafts → Publish.

Hub registers ChatGPT itself, so there is no client ID or secret to copy. When the access you chose runs out (1, 7 or 30 days), ChatGPT asks you to sign in again. You can see and revoke the access at any time in Agents; revoking takes effect on ChatGPT's next request.

What you approve on Hub's consent screen

Prompts you can paste

Replace the bracketed parts. Naming the tools keeps ChatGPT from guessing the order.

Check the connection, read-only

Use Mellow Hub. Call whoami, then list_channels. Tell me which accounts
you can post to, their channel IDs, whether this connection is in review
or autopilot mode, and how many posts you may still create today.
Do not create, schedule or publish anything.

One post to several networks, now

Use Mellow Hub. Write a post about [topic] for my LinkedIn, X and
Threads channels. Keep the X version under 280 characters and put it in
perChannel. Call validate_post and fix every issue it reports, then show
me the final text before publishing. After I say yes, call create_post
once with idempotencyKey "[topic]-[date]-1", then get_post, and tell me
each network's status and link.

A week planned in one go

Use Mellow Hub. Plan five posts for [brand], Monday to Friday at 09:00
[your timezone], for my Instagram and Facebook channels, each with the
image at [public https URL]. Register each image with register_media,
validate each post, then schedule them with create_post, scheduledAt
written with an explicit UTC offset, one idempotencyKey per post. List
the scheduled posts with list_posts at the end.

Images and video reach Hub as public https links, or as files you upload in Hub's composer. Each network fetches the file when it publishes.

What we tested in ChatGPT

On October 2, 2026, we added Hub to ChatGPT on the web as a developer-mode app and ran eight cases with a test account whose only channel was a Bluesky profile:

• ChatGPT published a post right away; Bluesky had it 11 seconds after the request.
• It scheduled a second post for the next morning. Hub published it on time, at 03:01 UTC on October 3, with nobody present.
• A 365-character text was refused before anything was sent: Bluesky allows 300, and validate_post said so.
• Asked to connect Bluesky with a password typed into the chat, it declined and pointed to Hub's Accounts screen instead.
• Asked to delete a published post, it explained that Hub cannot, and that deleting happens on the network.

Not tested yet in ChatGPT: networks other than Bluesky, video, and publishing the app to a whole workspace.

If your ChatGPT plan can't add it

• Claude adds Hub as a custom connector on Free, Pro, Max, Team and Enterprise; Free is limited to one custom connector.
• Claude Code, Cursor and other MCP clients connect to the same URL; see publishing through an MCP server.
• Hub's own assistant writes captions, hashtags and shorter versions in the composer, with AI writing included in every plan.

Questions

Related

• Post to social media from Claude.
• Publish to social media with an MCP server: the workflow for every network.
• Network guides: Instagram, TikTok, YouTube, X, LinkedIn, Threads, Bluesky, Pinterest, Facebook.
• API and MCP reference and rules for every network.
• Plans: 7 days for $0, and money back for a payment followed by 30 days with nothing published.