How to Turn a Blog Post into Social Media Posts with AI

To turn a blog post into social media posts with AI, give the article URL to a tool that writes one caption per network, within each network's character limit, and hands you a draft to review instead of publishing. In PostBoost that is Tools → Repurpose: paste the URL, tick your accounts, and you get a caption for every account plus carousel slides, saved as one draft post. If you just want captions, the free Blog to Social Media tool writes them without an account and opens any one of them as a PostBoost draft.

Below: why one caption for every network fails, what to take from an article, and the three ways to do it (free tool, app, API or AI assistant), with what each costs.

Why one caption for every network doesn't work#

The same paragraph cannot fit everywhere. Each network has its own limit and counts characters its own way:

A LinkedIn post cut down to 280 characters loses its argument, and an X post copied to LinkedIn looks thin. Paste any draft into the free social media character counter to see how it fits on all of them at once.

What to take from the article#

Good repurposing pulls a different piece of the article for each format, rather than shrinking the whole thing:

• Short networks (X, Bluesky, Threads): one claim or one surprising detail, and the link. The opening line has to stand on its own.
• LinkedIn and Facebook: the argument. Problem, what you found, what the reader should do, then the link.
• Instagram and LinkedIn carousels: the steps or key points, one per slide, with a hook first and a call to action last.
• Not at all: your intro, your SEO paragraphs and anything that only makes sense next to the article.

PostBoost's Repurpose follows this split: captions are written per network and per limit, and the carousel is built from the key points (at most 25 words per slide).

Option 1: the free tool (captions, no account needed)#

1. Open the Blog to Social Media tool.
2. Paste the blog URL and pick up to 8 platforms (Facebook, Instagram, X, LinkedIn, Pinterest, YouTube, TikTok, Mastodon).
3. Choose length, tone, hashtags and a call to action, then generate.

You get one caption per platform. Copy it, or click Schedule this one on its card to open that caption as a draft in PostBoost (after a free signup if you are not signed in), where you add the article link and images, pick your accounts and schedule it. Each click opens one caption as its own draft; the tool makes no images or carousel slides.

Option 2: Repurpose in PostBoost (captions, slides and a draft)#

In your workspace, open Tools in the sidebar, then Repurpose (under Automation; workspace admins and members see it).

1. Source: choose Article URL and paste the link. The same page takes a YouTube video, a PDF (upload up to 20 MB, text PDFs only) or Text.
2. Accounts: tick the accounts to write for. Leave all unticked to write for every connected account.
3. Options: tone, length, hashtags, call to action, language (empty means the same as the source), carousel slides (3 to 8) and extra instructions such as "mention our free trial".
4. Keep Make carousel slides, Use the workspace brand voice and Save the result as a draft post ticked, then click Repurpose.

The run is queued; you can leave the page, and the draft appears in Posts when it is ready. Open it in the composer, edit each account's version and schedule it.

What the draft contains:

• A caption per account, written for that network and its limit.
• 1080×1350 carousel slides: up to 10 on Instagram, Facebook and Threads, up to 9 on LinkedIn, up to 4 on X and Bluesky, the cover slide on other networks, none on YouTube and TikTok.
• Without slides, the article image is attached instead when the page has one.

If your captions should sound like you rather than like a generic AI, set up a brand voice first: How to make AI captions sound like your brand.

Option 3: the API or your AI assistant#

Automate it when you publish often, for example from your CMS's "post published" webhook:

curl -X POST "https://postboost.co/app/api/$WORKSPACE_UUID/ai/repurpose" \
  -H "Authorization: Bearer $POSTBOOST_API_TOKEN" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{
    "source_type": "url",
    "url": "https://example.com/blog/our-launch",
    "platforms": ["linkedin_page", "instagram"],
    "slide_count": 5
  }'

The response holds data.captions[] (each with content, character_count and character_limit), data.slides[] and data.post_uuid of the draft. Send an Idempotency-Key so a retried call does not create a second draft.

The call waits up to 20 seconds. A run that takes longer answers 202 instead, with data.run_id and data.status_url. Poll that URL (GET /app/api/{workspaceUuid}/ai/repurpose/runs/{runId}) every few seconds until data.status is ok, partial or failed; an ok or partial run returns the same body in data.result for one hour (the draft post stays). From a webhook or CMS hook, send "async": true to get the 202 right away instead of holding the connection open. Details: Repurposing docs and the API reference.

From Claude or another assistant connected to PostBoost's MCP connector, ask in plain words: "Turn this article into posts for our LinkedIn Page and Instagram, five slides, friendly tone." The repurpose-content tool saves a draft; you review and schedule it. Setup: How to schedule social media posts with Claude.

What it costs#

• AI text credits: one per target account, plus one for the carousel outline.
• AI image credits: one per carousel, charged only when slides were rendered.
• Example: an article sent to 4 accounts with a carousel costs 5 text credits and 1 image credit. Without enough credits nothing runs and no credit is spent.

Each plan includes a monthly allowance of AI text and image credits; see plans.

Check the draft before you schedule it#

AI drafts save time, but they still need a person to read them:

• Facts and numbers match the article, word for word where it matters.
• The first line works without the rest; most feeds cut long posts after a line or two.
• The link is in every caption that needs it. On X it always costs 23 characters.
• Hashtags are relevant, and no more than 5 on Instagram.
• AI labels: repurposed drafts are marked AI-generated, and PostBoost sets the native AI label on TikTok, Instagram and YouTube (AI disclosure).

Want a thread instead of a single post? Paste the article into the free X thread maker: it splits text at paragraphs and sentences into numbered posts that fit X, Threads, Bluesky or Mastodon.