Free tools for short-form video

Write the hook, the caption and the prompt, and get every size right. The AI writing tools and the calculator are free to use without an account.

AI Hook GeneratorTen scroll-stopping opening lines for TikTok, Reels and Shorts.
Caption & Hashtag GeneratorThree captions plus a mix of broad, niche and specific hashtags.
AI Video Prompt GeneratorTurn a rough idea into a prompt written for VEO, Kling, Seedance or Hailuo.
Aspect Ratio CalculatorPixel sizes per platform, safe zones and resize math.
Virality PredictorAn AI read on your hook, retention risks and edits before you post.Runs in the studio: 2 credits per clip.

What each tool does

What you put in, what you get back and who it helps.

AI Hook Generator

Writes the first line of a short video. You describe the video, pick TikTok, Reels or Shorts and one of five tones, and it returns ten opening lines, each from a different angle such as a curiosity gap, a mistake callout or a number list.

Who it is for: Creators and social media managers who have the idea but not the first three seconds, and anyone who wants to test opposite openings on the same video.

You enter: One sentence about the video; platform, tone and audience are optional
You get: 10 hooks, each labelled with its angle
Cost: Free, no account

Caption & Hashtag Generator

Writes the post text. From a description of the video it returns three captions (a short one, one that asks a question, one longer story caption) and about a dozen hashtags sorted into broad, niche and specific groups.

Who it is for: Anyone posting to TikTok, Instagram or YouTube Shorts who wants a caption that matches the platform, and small shops that post often and do not want to reuse the same tags.

You enter: What happens in the video; platform, tone and emojis on or off
You get: 3 captions and three groups of hashtags, copied in one click
Cost: Free, no account

AI Video Prompt Generator

Turns a rough idea into a full text-to-video prompt written for one model: VEO 3.1 Fast, Kling 4.0, Seedance 2.5, Hailuo 2.3. Each model reads prompts differently (audio lines, numbered shots, bracketed camera commands), so the wording changes with the model you pick.

Who it is for: People new to AI video who get vague results from one-line prompts, and editors who move between models and want the prompt rewritten for each.

You enter: One line with who, what happens and where; model, aspect ratio and style
You get: One ready prompt plus short tips for that model
Cost: Free, no account. Generating the video uses credits

Aspect Ratio Calculator

Gives the pixel size, ratio and safe zone for 10 placements, from TikTok and Reels to YouTube, LinkedIn and Pinterest. It also does resize math and shows how much of the picture a crop from one ratio to another would cut.

Who it is for: Editors exporting one video for several apps, designers placing text and logos, and anyone turning a 16:9 video into 9:16.

You enter: A platform, or any width and height
You get: Sizes, safe-zone overlay, resize numbers and a crop versus reframe comparison
Cost: Free. Runs in your browser, nothing is uploaded

Virality Predictor

Reads a finished video and returns a 0 to 100 score, a rating for the first three seconds, the moments where viewers are likely to leave and specific edits to try before you post.

Who it is for: Creators and brands deciding which cut to post, and teams that want a second opinion on a hook before spending on ads.

You enter: One uploaded video
You get: A score, a hook rating, retention risks and suggested edits
Cost: 2 credits per video in the studio (new accounts start with 4 free credits)

From idea to posted video

The tools follow the order a short video is made in.

AI Hook Generator. Before you film or generate: settle the opening line.
AI Video Prompt Generator. When the clip is AI-made: turn the idea into a prompt for the model you will use.
Aspect Ratio Calculator. Before you export: check the size and keep text out of the app buttons.
Virality Predictor. With the finished cut: score the hook and fix weak spots.
Caption & Hashtag Generator. At posting time: write the caption and pick a few hashtags.

To make the clip itself, text to video and image to video run on the same models the prompt generator writes for, and the prompt guides explain each model in depth. Prices per clip are on the pricing page.

Frequently asked questions

Limits, sign-up, privacy and what the results can be used for.

Are these tools really free?

The hook generator, the caption and hashtag generator, the prompt generator and the aspect ratio calculator are free and need no account. The three AI writing tools share a fair-use limit of 5 runs per 10 minutes and 20 per day for each visitor. The Virality Predictor runs in the studio and costs 2 credits per video.

Do I need to sign up?

No. You only need an account when you want Viralance to make the video itself, for example from a hook or a prompt you generated here. New accounts get 4 free credits after email verification, with no card.

Which tool should I start with?

Start with the hook generator if you already know the topic, since the first line decides whether people keep watching. If you are making the clip with AI, go to the prompt generator next. Use the aspect ratio calculator before exporting and the caption generator when you post.

Which AI video models does the prompt generator write for?

VEO 3.1 Fast, Kling 4.0, Seedance 2.5, Hailuo 2.3. The prompt is always written in English, because the models follow English most reliably, and it opens in the studio with the same model selected if you choose to generate it.

Is my text or video stored?

The aspect ratio calculator runs entirely in your browser and uses no files. The AI writing tools send your description to our server to write the result and do not need your name or email. A video is only uploaded when you use the Virality Predictor in your account.

Can I use the results commercially?

Yes. Hooks, captions, hashtags and prompts are plain text you can use in your own posts and ads. Check brand and product hashtags before you use them: only tag names you own or have permission to use.