AI Caption Generator
Tell it what the post is about (a sentence is enough) choose a tone and you get five captions to pick from. Each platform gets its own rules: Instagram captions lead with a hook, LinkedIn posts use short lines, X posts stay under 280. Edit anything, copy it, or schedule it straight to your accounts.
Results come from Claude, tuned per platform. Edit them: the best version is the one that sounds like you. We do not store what you type.
What makes a good Social Media caption
The first line is the whole game on every platform: it is what shows before "more" and what decides whether anyone reads on. After that, one idea per post, a question or a clear next step at the end, and hashtags where the platform still rewards them.
How to get better results
- Give a specific brief: "our spring menu, launching Monday, photo of the pistachio croissant" beats "food post".
- Name the audience if it matters: "for first-time home buyers", "for dentists".
- Put must-include words (a product name, a discount code, a link) in the "anything to include" field.
- Pick the caption that sounds most like you and cut the rest. Generated captions are a starting point, not the post.
Frequently asked questions
Is the caption generator free?
Yes. Ten generations a day without an account, and unlimited inside Social by InstantDM's composer.
Which AI does it use?
Claude, with a prompt written for each platform's length and style.
Do you store what I type?
No. The brief is sent to generate the captions and is not saved.
How long should a caption be?
Short enough that the first line shows in full: about 125 characters on Instagram, 210 on LinkedIn, 280 total on X.
Related free tools
Write it here, publish it everywhere
Social by InstantDM schedules to Instagram, Facebook, X, LinkedIn, TikTok, Pinterest, Threads and YouTube from one calendar, with AI captions, previews and an API. Start free — $0 today, cancel anytime.
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