Is there a free AI video prompt generator?

Yes. Our video prompt builder is free, needs no account, and turns a character, a format and one line of action into a structured prompt with references, an avoid list, camera, sound and a timestamped timeline. It is a deterministic template, not an AI: it runs in your browser and fills in the same structure we used for our published videos.

What the builder does

1. Pick a character. One to three from the free Malfoid & Friends pack, or "Your own": type a name and what they look like.
2. Pick a format: phone-POV livestream, dance to a song, tutorial, storytime, reaction, walk-in trend, or cinematic scene. Each format sets a default camera and vibe and its own beats, sounds and avoid lines.
3. Adjust style, camera, vibe and length (5, 10 or 15 seconds) if you want.
4. Type what happens in one line, and optionally a spoken line, which goes into the timeline in quotes.
5. Copy the prompt. There is also a one-paragraph version and a "Make it in Cast" button.

Here is what it produced for a ginger cat captain doing a 10-second livestream (trimmed):

References:
@Image1: Captain Whiskers (attach your own picture of them here). Keep this face, hair and outfit exactly.

Avoid: No subtitles, captions or on-screen text. No logos, watermarks or interface overlays. The camera itself is never visible: no phone, phone case or hand holding a phone in frame. No slow motion. No streaming-interface overlays, chat bubbles, hearts or viewer counts. No change to any face or outfit.

Timeline (10 s, Phone-POV livestream):
0-3s: Captain Whiskers looks straight into the lens and opens the stream mid-conversation with the chat.
3-7s: Captain Whiskers reads his hate comments out loud and claps back at each one, saying: "Reading my hate mail. Live."
7-10s: The turn: something goes wrong, or the character softens for one second, then recovers their cool.

End with action.

Why a template and not an AI

The builder makes no AI call, so it is instant, free to run, and gives the same output for the same inputs. The structure it fills in is the one behind every video in our prompt library: references, one style sentence, an avoid list, cast with camera, pacing and sound, then one beat per two to three seconds. Its camera and vibe wording is the same catalogue text Cast's app uses, and it strips franchise names from everything you type, because they trigger copyright filters.

The trade-off is honesty about its limits:

• It does not write your story. The opening and closing beats are stock lines per format; only your action and spoken line are yours. Edit the stock beats before you use them.
• It cannot see your picture. It reserves @Image1 for one; attach it in your video tool.
• It only knows 5, 10 and 15 second clips.

Does it work for Seedance, Kling and Veo?

We built and tested the structure on Seedance, where reference tags like @Image1 and @Audio1 map to attached files. On other models, treat it as a starting point and check their limits. Veo 3.1 accepts up to three reference images and generates 4, 6 or 8 second clips, with reference images only at 8 seconds^[1][2], so trim the timeline to fit. Kling 4.0's Omni Reference combines up to 15 reference assets^[3]. We have not tested how either reads our tag names. Sora prompts have less use now: OpenAI shut down the Sora 2 API on 2026-09-24^[4].

Other free options

• Write it by hand with how to write an AI video prompt. It takes about five minutes once you know the parts.
• Copy and adapt a real prompt from AI video prompt examples.
• Paste the builder's output into a general chat assistant and ask it to rewrite the stock beats around your story. Keep the structure.

Where Cast fits

• You want the prompt turned straight into a video: "Make it in Cast" carries your character, line, camera, vibe and length over, and the first 5-second video is free with no sign-up.
• You do not want to write prompts at all: in Cast an LLM (Claude via Atlas Cloud) writes the full prompt from your one line.

Where it does not:

• Using your own photo as @Image1: Cast has no photo upload; characters are drawn from text.
• Long or multi-shot prompts: the builder and Cast both stop at 15 seconds.

People also ask

What does an AI video prompt generator do?

It turns a few choices into a full prompt in the shape video models follow best. Ours outputs references, style, avoid list, camera, sound and a timed timeline.

Do I need an account?

No. The builder runs entirely in your browser with no login, and nothing you type is sent to an AI.

What is the one-paragraph version?

The same inputs as one dense paragraph, in the form Cast sends to Seedance when its AI prompt writer is not used. Some tools prefer a single paragraph.

Is the output different every time?

No. It is deterministic: the same inputs give the same prompt. Change the action line, format or camera to get a different one.

Sources

Claims about other companies come from their own pages, read on the date shown. Products and prices change; check the link for the current version.

1. Google: Veo on the Gemini API, reference images (read 2026-10-18)
2. Google: Veo on the Gemini API, durations (read 2026-10-18)
3. Kling AI: AI video generator feature page (read 2026-10-18)
4. OpenAI: Sora 2 model page (read 2026-10-18)

Related answers

• How do I write a prompt for an AI video?
• What are some good AI video prompt examples?
• What prompt makes a good AI dance video?
• What should an image-to-video prompt say?
• How do I write a good Seedance prompt?

Part of the Cast answers library (Prompting).

Updated 2026-10-18