AI companion platforms give you more control than most people use. Behind the chat window are text fields for a persona, a backstory, a greeting and example dialogue, and on some platforms lorebooks, journals and sharing tools. This section explains how to use them on named platforms, based on what each one documents. It covers character design on platforms, not generic prompt engineering.
We did not create accounts or build characters. Field names, limits and rules come from each platform's help center, wiki, terms and guidelines, checked on October 20, 2026. Every example in this section involves adult characters only, and each platform's content rules apply to whatever you publish.
Where to Start
| Your goal | Read |
|---|---|
| Choose where to publish | Best platforms for AI character creators |
| Build a first character | How to create an AI character |
| Write the text well | How to write a character prompt |
| Give it a distinct voice | AI character personality design |
| Make it remember | AI character memory setup |
| Start and steer scenes | AI roleplay prompts |
Three Facts to Know Before You Begin
- Limits vary widely. Character.AI allows a Definition of up to 32,000 characters, SpicyChat a Personality of up to 5,000 and Kindroid 2,000 (2,500 for subscribers). Longer is not better, because the text shares the context window with the chat.
- Platform rules sit above your text. Character.AI bans pornographic content and nudity, and adult platforms ban characters who are minors and other listed categories. No definition changes that.
- Memory is partly in the user's hands. Pins and chat memory are usually user-managed, so a creator's job is a solid starting text and, where available, a lorebook.
If you only want to chat with a character rather than build one, start with apps with custom characters or our guide to creating an AI girlfriend. The glossary entry on the character card explains the file format many tools import.