AI dialogue generator where each character has their own voice
Write each character a voice and a secret, then read the conversation they have without you.
Locked in a room
A museum storage room after closing. The door has jammed, phones have no signal, and the night guard won't be back until dawn.
In shortCastfic is an AI dialogue generator for scenes with 2 to 4 characters. Each speaker is played separately and knows only their own secret, so voices stay distinct. Pause, add narration or pick who talks next, then export a Fountain screenplay. 1 free scene without an account, then 1 a day with Google sign-in.
How to generate dialogue between your characters
- Write a card for each speaker with two sample lines in their voice.
- Pick a setting. Locked in a room is a good one for dialogue because nobody can leave.
- Press play and read. Pause to choose who speaks next, or redo a round.
- Export the scene as a Fountain screenplay, Markdown or Word.
Why the voices stay different
Most generators write all the lines in one pass, and the characters tend to blur into one voice. In Castfic each character is played separately from their own card, so a line can only use what that character knows.
An example: locked in a records room
Illustrative example: Yusuf is the archivist, careful and dry. Marguerite is the inspector, blunt. Dev is the intern, who has the key in his pocket.
| Speaker | Line |
|---|---|
| Marguerite | "Door's stuck. Yusuf, whose idea was the lock?" |
| Yusuf | "The lock is from 1974. It has opinions. It doesn't share them." |
| Dev | "Maybe we, uh, wait. Someone will come." |
| Marguerite | "You're sweating through a cardigan, Dev." |
Marguerite's last line is her reading Dev. Dev never mentions the key; the nerves are the clue. (Illustrative lines; real scenes vary.)
The screenplay version
The same scene exported as Fountain uses scene headings, character names and dialogue blocks, so you can open it in any screenwriting app. You can also choose a prose rewrite in sweet, angst, comedy or AO3 style.
How Castfic compares
| Castfic | Sudowrite | NovelAI | Type.ai | ChatGPT | |
|---|---|---|---|---|---|
| Free tier | 1 free scene without an account, then 1 a day with Google sign-in, plus a free Daily Scene | Free trial, no card; no ongoing free plan | Free trial: 50 text generations | Free plan with limited credits | Free plan with usage limits |
| Cheapest paid plan | $4.99 for 15 scenes, or $7.99/mo | $10/mo | $10/mo, unlimited text | $8/mo billed yearly | $20/mo (Plus) |
| Characters keep separate secrets | Yes, each is played separately | — | — | — | — |
| Scene to prose or screenplay | One click: prose or Fountain, 4 styles | Prose | Prose | Prose | Prose if you ask |
| OC memory across sessions | Written back to each character card | Story Bible | Lorebook | — | — |
| All-ages by design | Yes, 13+ with filters on | — | — | — | — |
Competitor details are from each product's public pages in October 2026 and may change. Product names are trademarks of their owners; Castfic is not affiliated with them.
Frequently asked questions
Can I get just the dialogue without prose?
Yes. The script view is the raw dialogue. Export it to Markdown, Fountain or Word as it is.
Can I control who speaks?
Yes. Pick who speaks next, add narration, choose one of two suggested branches, or redo a round.
How long is a scene?
8 rounds, usually under a minute.
Is it good for a script I plan to sell?
Treat it as a draft partner for blocking out who says what. Read the output carefully and edit it before you use it.
Can I use it without signing in?
Your first scene needs no account. 1 free scene without an account, then 1 free scene a day after signing in with Google, plus the free Daily Scene.
Try it with your own characters
1 free scene without an account, then 1 free scene a day after signing in with Google, plus the free Daily Scene.
Try a scene free