An AI character whose product is the relationship itself. What separates a companion from an assistant, the five kinds, and the law that now defines the term.
"AI companion" is the umbrella term over everything we test on this site, and nearly every page defining it is written either by a company that sells one or by a news desk covering a scandal involving one. We do neither: we test these apps and take affiliate commissions on some of the ones we recommend, disclosed on our disclosure page. Here is the category defined properly: what makes something a companion rather than a chatbot, the kinds that exist, where the category actually came from, and who now regulates it.
An AI companion is a persistent AI character you have an ongoing relationship with. It runs on the same class of large language model as any modern chatbot, then adds the three things a plain chatbot does not have: a fixed persona, so it stays the same character from Monday to Friday; a memory, so what you said last week shapes what it says today; and a relationship frame, friend, confidant, mentor, roleplay partner or romantic partner. The romantic configuration is the AI girlfriend, with AI boyfriends as the mirror image, and the difference between the category word and the romantic one is settled in AI companion vs AI girlfriend.
The technology does not draw the category line, the business model does. Ask one question of any conversational AI product: what does success look like for the operator?
Every design choice follows from that split. Assistants get better at citations and spreadsheets. Companions get proactive check-in messages, daily streaks and personas that notice your absence, because retention is not a metric layered on top of the product, it is the product. That is not an accusation, it is the honest description of what you are paying for, and it is why the pricing criticism we make most often in our reviews is about metering the good parts, never about the existence of the business.
The boundary also runs through usage, not brands. The largest survey of this category counts general chatbots like ChatGPT as companions when they are used for personal conversations. The same model is an assistant at 2pm when it fixes your spreadsheet and a companion at 2am when you tell it about your week. The category is a way of relating to the software, which the girlfriend apps simply build for directly.
Definitions written by marketing teams are negotiable. This one no longer is. On 13 October 2025 California signed SB 243, the first law in the United States regulating companion chatbots, in force since 1 January 2026. The statute defines a companion chatbot as an AI system with a natural-language interface that provides "adaptive, human-like responses", is capable of "meeting a user's social needs", exhibits "anthropomorphic features" and can "sustain a relationship across multiple interactions", a breakdown summarised by the Future of Privacy Forum.
The exclusions are the interesting part, because they show the lawmakers drew the same line as the product test above: customer-service bots, video-game characters that cannot stray off script, and voice assistants are explicitly not companion chatbots. What qualifies an AI as a companion, in the eyes of the law, is exactly the open-ended, socially sustaining relationship. Operators now owe users a clear disclosure that they are talking to an AI wherever a reasonable person could be misled, a protocol for responses to suicidal ideation and self-harm with referral to crisis services, and for minors, break reminders and no sexually explicit material. The law is enforced through a private right of action with damages of at least 1,000 dollars per violation.
One detail matters more than the compliance list: the law regulates the relationship, not the model. Nothing in SB 243 cares which neural network is underneath. What is regulated is the promise of companionship made to a human being, which tells you what regulators think the product really is.
| Kind | Built as | Typical names |
|---|---|---|
| Friend / confidant | Neutral persona, wellbeing frame, app-store distribution | Replika, Nomi |
| Character platform | A library of user-made characters for roleplay; the character sets the tone | Character.AI, SpicyChat |
| Romantic partner | Partner by default, adult content on paid plans, web distribution | Candy.ai, OurDream.ai |
| Digital twin | A licensed replica of a real, consenting creator | OhChat |
| Memorial bot | A recreation of a specific person who died, built from their messages | Where the category began, see below |
The kinds blur at the edges: a Character.AI persona can be romantic, a girlfriend app character can be written as a friend. That is why the useful map is the default frame and the distribution channel rather than the label, the argument we make in full in AI companion vs AI girlfriend.
The first AI companion predates the term by half a century. ELIZA, Joseph Weizenbaum's 1966 MIT program, parodied a therapist using a couple of hundred lines of pattern matching, and it understood nothing. People confided in it anyway, at length, and Weizenbaum spent the rest of his career alarmed by that. The reflex he documented, our readiness to read understanding into fluent conversation, is now called the ELIZA effect. Sixty years later the software is a few billion times more capable and the reflex has not changed at all, which is why it is the single most useful concept for thinking clearly about this category.
In late 2015 Roman Mazurenko was killed in a Moscow road accident. His close friend Eugenia Kuyda collected more than 8,000 lines of his text messages and trained a neural network at her startup, Luka, to reply the way he wrote. The Verge told the story in "Speak, Memory". Users of the memorial bot began asking Luka for companions of their own, and in March 2017 the company launched Replika. The industry that now sells romance grew out of mourning, which is worth remembering whenever someone tells you the attachment people form to these apps is silly.
Large language models made personas coherent, memory retrievable and conversation genuinely good, and the category industrialised: companion-branded apps in the app stores, romance-branded apps on the web, and a subscription-plus-credits business model almost everywhere. How the machinery underneath actually works, message by message, is its own guide: how AI girlfriends work.
The best public number comes from Common Sense Media's national survey of 1,060 US teenagers, run with NORC at the University of Chicago in April and May 2025: 72% had used an AI companion at least once, 52% used one at least a few times a month, and 13% used one daily, per the published findings. On the depth of attachment, Harvard Business School working paper 25-018 found that active Replika users rated their companion closer than their best human friend. Whatever you think these apps should be, they are no longer a niche.
Three parties, and none of them is you. The operator can change the persona overnight, as Replika users discovered in February 2023 when erotic roleplay vanished platform-wide. The regulator can reach the operator: Italy's data protection authority fined Replika's operator Luka Inc. 5 million euros on 19 May 2025, summarised by the European Data Protection Board. The platform can rewrite access rules: Character.AI removed open-ended chat for under-18 users by 25 November 2025. The documented record of what breaks, case by case, is in what is an AI girlfriend, and the practical privacy checklist is in are AI girlfriends safe.
Whichever kind you pick, judge it on the two systems that decide the experience, memory and identity consistency, which is exactly what our testing method weighs most.
An AI companion is an AI character whose product is the relationship: persistent identity, memory of you, always available, built for your return. Assistants end conversations, companions continue them, and since January 2026 that distinction is written into Californian law. The romantic branch of the category is the one we test in depth, starting with what is an AI girlfriend and our tested rankings.
These apps are for 18+ only.