LinkedIn3,000 characters
We spent six weeks on a feature nobody asked for. Here is why that was the right call — and the three signals that told us so before the data did.
Narrative, first person, one idea per paragraph
One input · seven native outputs
A free AI post generator that knows where the post is going
Most generators write one paragraph and hand it back for you to paste. This one writes a different post for each network — because 280 characters and 3,000 characters are not the same piece of writing — then schedules and publishes it on the slot you pick.
Free plan: 20 credits a month, drafts from 1 credit. No card.
Your input
“We shipped a feature nobody asked for. Six weeks of work. It’s now our second-most used feature. Post about the lesson.”
X (Twitter)280 characters
Nobody asked for it. We built it anyway. Six weeks later it is the second-most used thing we ship.
One claim, no wind-up, no hashtags
Instagram2,200 characters · media required
Nobody asked. We built it anyway 👇 Six weeks. Second-most used feature we ship.
Hook line, whitespace, caption-style tail
Bluesky300 graphemes
Built a thing nobody asked for. It is now our second-most used feature. Sometimes the roadmap is wrong.
Dry, conversational, link-light
What happens between your sentence and a scheduled post
01
Knows the destination
Pick the profiles first. The generator is told each network’s character ceiling, hashtag norms and formatting before it reads your idea.
02
Writes per network
Not one draft resized seven ways. Each network gets copy built for its length, its line-break conventions and its hashtag norms.
03
Generates the visual
A matching image from a prompt, steered by a reference image if you give one, returned as a hosted URL ready to attach.
04
Pre-flights the result
Character counts, missing media on networks that require it, unconnected profiles and the credit cost — before anything is queued.
The tell that a post was cross-posted by a machine
A LinkedIn essay on X
Truncated mid-sentence with a “…” and a link nobody clicks. The 280-character ceiling is not a suggestion.
Instagram hashtags on LinkedIn
Eleven hashtags under a professional post reads as spam on one network and as normal on another.
A caption with no image
Instagram will not accept a post without media at all, and YouTube Shorts needs a vertical video. Text-only fan-outs quietly drop those networks.
Generating per network costs nothing extra in effort — you still write one idea — and it is the difference between a feed presence and an obvious broadcast.
Most AI post generators hand you a caption. Then what?
The free generators are genuinely good at the writing part. The gap is what happens next — you still have the copy in a clipboard and seven tabs to open.
A caption generator
- Type a prompt, get a caption.
- Copy it.
- Open the network, paste, adjust the length by hand.
- Repeat for every other network.
- Find your own image.
A generator wired to a queue
- Give it the idea once.
- It writes a native version per network, inside each real limit.
- Attach your own media, or generate an image on a paid plan.
- Pre-flight reports overruns, missing media and the credit cost.
- You approve, and it publishes on the slot you picked.
Free plan
20 credits a month, no card
One balance for everything. A draft in the composer costs 1 credit and a delivery costs 1 per profile, so twenty credits is twenty posts written and published — or more, if Claude, ChatGPT or Cursor does the drafting over MCP, which costs PostMCP nothing. AI image generation is not on Free: each image costs 20 credits, which is the entire monthly allowance, so it is a paid-plan feature — on Free you attach your own media instead.
AI post generation FAQ
Is there a free AI social media post generator?+
Plenty, and most of them are worth trying — Canva, QuillBot, Buffer and SocialBee all run free caption generators. PostMCP’s Free Forever plan includes 20 credits a month with no card; a draft in the composer costs 1 credit and a delivery costs 1, so you can generate and actually schedule from the same balance. And if you draft in Claude, ChatGPT or Cursor over MCP, the drafting costs PostMCP nothing at all.
Do I need to sign up to use it?+
Yes — a free account, no card. Some generators let you produce a caption without an account at all, and if a one-off caption is genuinely all you need, one of those is the faster route. An account exists here because the generator is wired to your connected profiles and their real limits, and because the output can go straight onto the calendar rather than into your clipboard.
Can it generate images as well as captions?+
Yes, on a paid plan. Image generation returns a hosted URL you can attach directly to the post, and passing a reference image keeps generated visuals in family. It costs 20 credits per image, which is why it is not on the free plan — that would be a whole month’s allowance for one picture. On Free you attach your own media, which Instagram and YouTube Shorts require on every post.
Can it write Instagram posts and captions?+
Yes, and it writes them as Instagram posts rather than as a resized LinkedIn paragraph — hook line first, whitespace between beats, hashtags where they earn their place, inside the 2,200-character caption limit. It can also generate the image, which Instagram requires on every post.
How does an AI social media post generator work?+
You give it the substance — a launch, a lesson, a link — and it produces publish-ready copy. PostMCP’s generator additionally knows the destination: it writes a separate version per network against that network’s real character ceiling and formatting conventions, then checks the result before anything is scheduled.
Will the posts sound like AI wrote them?+
That depends entirely on what you tell it. In the composer, the prompt is the brief — say the tone and the audience. For something that sticks, draft through your own agent over MCP: a voice brief in a Claude Project or ChatGPT’s custom instructions is read before every generation, so the output is recognisably yours rather than competent generic copy.
Can it generate images as well as text?+
Yes. Image generation returns a hosted URL you can attach directly to the post. Pass a reference image and it steers the visual output, so generated visuals stay in family rather than drifting between styles.
Does it write hashtags?+
It will, when the network warrants them. Hashtag habits differ sharply — heavy on Instagram, near-useless on LinkedIn, actively harmful on X — so the generator applies per-network convention rather than pasting the same block everywhere.
What does generation cost?+
One meter. A draft in the composer costs 1 credit however many networks it writes for; an AI image costs 20; a delivery costs 1 per profile, 5 for X. Drafting inside Claude, ChatGPT or Cursor over MCP costs PostMCP nothing — you pay only when it publishes. Free Forever includes 20 credits a month.
Can I edit what it produces before it goes out?+
Always. Generated copy lands as a draft or a pending approval, never as something already published. Edit it, re-target it, move its slot, or throw it away — nothing reaches a network until you say so.