Free caption writer for X, LinkedIn, TikTok and YouTube.
Say what the product is and what the post is about. Get a caption written for each platform the way people there actually post: short on X, a story on LinkedIn, a hook and hashtags on TikTok, a description on YouTube. Free, no sign-up.
Want it as a video too? Paste your site and Siren makes the video in your brand, for $9.99.
How each platform likes it
- X
- One idea, under 280 characters, first line does the work. No link in the launch post itself; put it in a reply. Hashtags rarely help.
- Write like one operator talking to another: open on a moment or a number, short paragraphs, end on a takeaway or a real question. Skip hashtags and 'excited to share'.
- TikTok
- The first line is read with the sound off, so it is the hook. Keep the body to a line or two and finish with three to five hashtags that fit the clip.
- YouTube
- It is a description, not a script. The first two lines show above the fold, so make them specific. A short paragraph of context, a plain call to action, then a few hashtags.
Questions
- Is it free?
- Yes. No account, no card. You can run it a few times an hour.
- Do you keep what I type?
- It goes to the AI model that writes the captions. Siren does not save it or tie it to you. Do not paste anything secret.
- Why no hashtags on LinkedIn?
- They rarely help reach there and make a post look automated. TikTok and YouTube are different: hashtags help people find the video.
- Can Siren post it for me?
- Yes. In Siren the caption comes with a video or ad creative in your brand, and Siren posts it to X, LinkedIn, TikTok and YouTube.
More free tools
a thousand voices, one signature
Words are half the post.
Siren makes the video or ad creative in your brand, writes the caption and posts it.
