Chatters AI – AI Companion & Character Chat App

Chatters AI is an AI companion and character chat app that lets users talk to realistic AI personas anytime — a friend, a flirt, a role-play partner, or a sounding board. We designed and built the product end to end: the mobile app, the backend, the LLM conversation pipeline, and the subscription model.

The brief

The client wanted an AI chat app that didn't feel like a chatbot. Conversations had to be natural, persistent, and emotionally consistent; characters needed distinct personalities that held up over long sessions; and the whole experience had to run smoothly on a consumer subscription model.

What we built

A character system with persistent memory. Each AI persona has a defined personality, backstory, interests, and conversational style. Conversations carry context across sessions, so a character remembers what the user shared yesterday and responds accordingly.

Natural-language conversation pipeline. The app runs on a model-agnostic LLM layer with prompt management, safety filtering, and response streaming. The architecture allows switching or mixing models without changing the app, keeping per-conversation cost under control at scale.

Voice and multimodal input. Users can speak instead of type; voice input is transcribed and handled in the same conversation flow.

Role-play and scenario modes. Alongside everyday chat, users can start structured role-play scenarios with a chosen character.

24/7 availability with instant replies. Response latency was a core product metric; streaming and backend caching keep replies fast under load.

Subscription and paywall flow. A premium tier unlocks unlimited messaging, additional characters, and extra features, implemented with App Store and Google Play subscriptions and server-side receipt validation.

Technical highlights

• Native iOS (Swift / SwiftUI) and Android (Kotlin) clients
• NestJS backend with PostgreSQL and Redis for session state and caching
• LLM abstraction layer supporting multiple providers, with prompt versioning and evaluation
• Streaming responses over WebSockets for a real-time chat feel
• Content safety filtering on both input and output
• Subscription management via RevenueCat with server-side validation
• Analytics and crash reporting for ongoing optimisation

Outcome

Chatters AI shipped to the App Store and Google Play and operates as a live subscription product. The model-agnostic architecture has allowed the product to adopt newer, cheaper, or better-performing models as they were released without rewriting the app.

Services provided

AI product strategy · Conversational AI architecture · LLM integration · Native iOS and Android development · Backend development · UI/UX design · Subscription and paywall implementation · App Store launch and ASO