How AI Girlfriend Apps Work

Behind the avatar and the pet names, an AI girlfriend app is a stack of fairly ordinary parts. General definitions come from vendor documentation; app facts come from each app's help center, policy or plan page, checked on October 20, 2026. We did not create accounts or test the apps. Our AI companion app guides have the how-tos.

The Language Model Behind the Chat

A large language model reads text and writes a fitting continuation. It works in tokens, small pieces of text: OpenAI's help center says 100 tokens are roughly 75 English words. Message limits, context sizes and prices are all counted in tokens or in the cost of producing them.

Where the model comes from varies:

• Presented as in-house: Nomi runs its own model line, Kindroid ships named models such as Ember and Polaris, Character.AI uses proprietary chat styles such as PipSqueak 3, and Chai says its models are trained in-house.
• Named outside provider: Talkie's FAQ says its characters are powered by MiniMax.
• Mixed: Replika's help center says it combines "our own and third party Large Language Models and scripted dialogue content", and its May 2026 privacy policy says de-identified conversation data goes to third-party AI language model providers, which it does not name.
• Your choice: Janitor AI runs its free JLLM by default or an external model you connect through an API proxy, and SpicyChat and CrushOn.AI let you pick among many models by tier.
• Not stated: Candy AI, EVA AI, Nastia AI, Kupid AI and Muah AI name no provider; Candy AI's privacy notice says third-party LLM providers "may receive the content of your messages".

Personas and Character Prompts

A model knows nothing about your companion until it is told. Apps send standing instructions ahead of the conversation, usually called a system prompt; Anthropic's documentation notes that setting a role there focuses the model's behavior and tone. In companion apps the same idea is a character definition: personality, backstory, speaking style, scenario, a greeting and example dialogue.

The fields differ by app. Nomi's Backstory+ has sections such as Backstory and Current Roleplay, Kindroid takes a personality of up to 2,000 characters (2,500 for subscribers), Character.AI allows a 32,000-character Character Definition, and Replika uses a free-text backstory. Our glossary entries on the character prompt and the character card define the terms, and creating an AI girlfriend step by step shows what five apps ask for.

Memory: How the App Remembers You

The context window is the model's working memory, and anything outside it is invisible unless the app puts it back. Windows are limited (SpicyChat's is 4,096 tokens on its free plan and up to 32,768 on its top tier), so apps add notes you write, automatic summaries and searchable stores of facts. The mechanics are in how AI companion memory works, and our ranking of AI companions with memory compares the apps.

Voice, Images and Video

Voice is usually a separate step: the language model writes the reply and a speech model reads it aloud. Nomi says its in-house voices have unlimited usage, while ElevenLabs voices draw on your own ElevenLabs allowance, a sign of a third-party service plugged in. Kindroid bills calls in audio credits, and CrushOn.AI clones a voice from about 30 seconds of audio with a consent checkbox. Voice cloning has no single standard; Microsoft, for one, requires a recorded consent statement (see voice cloning). See AI girlfriends with voice.

Images come from image models, not the chat model. SpicyChat's docs name the DreamShaper-8 diffusion model for its Conversation Images, and Nomi's V5 system builds "anchors" from reference images. Video is a further step: Candy AI has no direct text-to-video and converts an image from chat into a short clip with tokens, while Nomi spends 6 credits on a standard-definition video and 10 on high definition. See AI girlfriends with image generation and AI girlfriend video.

Moderation: Filters, Rules and App Stores

"Filtered" and "unfiltered" are marketing words for a stack of separate controls:

• Model behavior and classifiers: Romantic AI's Content Management Policy says its models are configured to refuse prohibited content, a proprietary filter screens inputs before generation, and text and images are classified before delivery.
• Account-level scans: Kindroid says it applies no filter to the AI itself, but scans messages and input fields automatically and warns before locking an account; no human reads content during that detection.
• Human review: Character.AI, Candy AI and DreamGF describe staff reviewing flagged or reported content.
• Platform rules: Character.AI bans pornographic content for every user, adults included.

App stores add another layer. Apple's guideline 1.2 requires apps with user-generated or AI content to filter objectionable material, offer reporting and let users block abusive accounts, and Google Play requires in-app reporting for apps that generate content with AI. That is why mobile versions are often stricter than the web: Kindroid's iOS and Android apps apply stricter image rules, Nomi has said its image rules are tightest in the mobile app, and Janitor AI's apps default to a Restricted Mode. SpicyChat's iOS app was removed in 2025 after Apple found it did not comply. More in unfiltered AI chat and the NSFW filter entry.

How AI Girlfriend Apps Make Money

Running models costs money, so every app has a billing model, and many combine several:

• Subscriptions: Nomi, Kindroid, Replika, SpicyChat and janitor+ sell monthly, quarterly or yearly plans.
• Credits, tokens or coins on top: Nomi credits, Kindroid selfie and audio credits, Candy AI and DreamGF tokens, Character.AI Charms, EVA AI Neurons.
• Advertising and pay per use: Character.AI, Talkie and Chai show ads on free tiers, and Janitor AI's Router bills third-party models per token.
• One-time payments: Kupid AI sells weekly, yearly and lifetime options that its pricing page says do not renew.

See AI girlfriend app pricing for the numbers and free vs paid apps for what free plans leave out.

Where Your Messages Go

The companion cannot answer without reading your messages, so they sit on the company's servers. Nomi and Kindroid both say plainly that their chats are not end-to-end encrypted, and several policies allow chats to be used to improve or train models. Running a model on your own computer is the way to keep text off a company's servers (see local vs cloud AI companions). Start the full picture with our AI companion privacy pillar.

It is also software, and laws now say so: California's SB 243 and New York's companion law require notices that the chatbot is AI. See US AI companion chatbot laws and the glossary entry on the AI companion.