Character.AI

Role-play chat with characters you define and talk to over time

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WHAT IT IS

Character.AI is a conversational product the company Character.AI released in September 2022, in which users create or pick characters and personas to talk with over long sessions or role-play. Its core is character definition and open-ended, continuing conversation rather than completing tasks. It is offered on the web and on mobile, with voice chat added later.

Why it matters

It turned “define a character and keep talking to it” into a consumer product, making entertainment- and companionship-oriented chatbots a category in their own right.

Key specs

Form: Web and mobile apps
Core: User-created characters and personas
Modality: Text, audio in; text, audio out

Capabilities

Beginner

Conversation & Instruction Following

Understand intent across turns and act on it

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Beginner

Text Generation

Continue a passage, one word at a time

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Related concepts

Expert

Prompting & Alignment

Making a model helpful, honest and harmless is harder than simply making it bigger

NLP & Large Language Models

Beginner

Safety, Alignment & Prompt Injection

A model optimises the proxy we wrote into the loss, never the thing we actually want — the gap between them is the whole alignment problem

AI Engineering, Safety & Ethics

Intermediate

Inference Optimization & Serving

Training happens once; inference happens a billion times a day — and serving is torn between fast first tokens and high throughput, which usually pull against each other

AI Engineering, Safety & Ethics