AI Caption Generator
Describe the post once and get captions shaped to each network's voice and character limit — three angles per brief, in your own brand voice.
- Free plan
- No card required
- 11+ networks
Generating runs on your Mediux account. The free plan includes 10 AI generations a month with no card — enough to try this properly.
Example outputSample
- Bold & punchy
80% less plastic. Same formula you already buy on repeat. The refill pouch lands today — and your bottle stays exactly where it is. 🌱
- Story-driven
Three years ago a customer emailed asking why she had to buy a new bottle every month. We did not have a good answer. Today we do — the refill pouch is live.
- Professional
Our refill pouch is now available, reducing packaging plastic by 80% per unit. Designed for existing bottle owners, with no change to the formula.
What it writes for each network
| Network | Written to | Hashtag approach |
|---|---|---|
| X (Twitter) | 280 chars | 1–2 tags. Space is the constraint. |
| Snapchat | 250 chars | Rarely used. Keep to 1 if any. |
| Bluesky | 300 chars | 2–3 tags. Discovery is still growing. |
| Threads | 500 chars | 1 tag only — Threads allows a single one. |
| Mastodon | 500 chars | 2–4 tags. Hashtags drive most discovery here. |
| 500 chars | 2–5 keyword-style tags. | |
| Google Business | ~150 before the fold | Not used. Write for search intent instead. |
| ~125 before the fold | 3–5 specific tags beat 30 broad ones. |
Writing a brief that gets something usable
- 1
Give it the goal, not the topic
'Product launch' produces a generic launch caption. 'Launching a refill pouch that cuts plastic by 80%, for existing customers who already love the original' produces something you might actually post.
- 2
Name the audience
The single biggest lever on register. Writing for procurement managers and writing for teenagers are different jobs, and the model cannot guess which one you are doing.
- 3
Set the brand voice first
Two minutes once, and every generation afterwards inherits it. Almost every complaint about AI-sounding output is a complaint about an unset voice.
- 4
Draft to the tightest network
Write for X's 280 first and expand for the roomier platforms. Going the other way means cutting the ending out of a caption that was built around it.
Questions
- Is it free?
- Yes, on the free plan — 10 AI generations a month with no credit card. Pro raises that to 300 and Agency to 500.
- Why do I need an account?
- Generating text costs real money to run, so it is metered per account. That is also what lets the output use your saved brand voice rather than a generic one — there is nowhere to store a voice without an account.
- Will it fit the character limit?
- Yes. The limit for each network is applied at generation time rather than flagged afterwards, so what comes back already fits. You can check anything by hand with the free character counter.
- Can I edit what it writes?
- Always, and editing never costs another generation. The draft lands in a composer where you can change a line, swap the hook or rewrite it entirely.
- Does it sound like generic AI?
- That depends entirely on whether you set a brand voice. With one saved, captions inherit your tone, your audience and the words you refuse to use. Without one, you get a competent generic draft — which is exactly what people complain about.
- How many options do I get?
- Three distinct angles per brief — bold and punchy, story-driven, and straight professional. Choosing between three is faster than re-prompting one.
Want this built into your workflow instead of a one-off?