AI agents thatbuild relationships.
Sonzai is the managed relationship layer for consumer AI agents. Persistent memory, personality, mood, and model-agnostic orchestration for AI companions, characters, avatars, and NPCs — through one API.
The model knows the world.
The agent knows your user.
Every user gets a private, persistent memory the agent reads on every turn.
Learn more →Memory, personality, mood, and relationship arc, carried across every session.
Multiple characters or NPCs can share canon, lore, and context — without losing per-user state.
Learn more →Your agent is only as good
as the harness around it.
Most teams build agents like one-off chatbots: a model with a prompt. That's not where the value lives. The value lives in the harness — the relational substrate that holds memory, personality, mood, tools, business context, and the rules of your product. Sonzai is the building blocks for a self-learning, self-adapting relational harness.
A harness is everything wrapped around the model that makes it act like a coherent agent in your world.
A moat that compounds while you sleep.
Every conversation deepens the relationship state — and trains Sonzai's proprietary self-learning models on each agent-user pair. Six months in, your harness has a per-user model no one else can replicate by swapping in a fresh LLM. A competitor would have to wait out the same compounding curve to catch up.
Acts inside your product, not next to it.
A harness gives the agent your tools, your data, your workflows, and the rules of your business. It stops being a chat window stuck on the side and starts being a teammate that moves things forward inside your system — safely and with permission.
Grounded, not improvising.
Without a harness, the model freestyles every turn — and hallucinates. With one, every answer is grounded in verified memory, current relationship state, and your business rules. Hallucinations drop. Recoveries get cheap. Trust compounds.
Sonzai gives you the building blocks for a self-learning, self-adapting relational harness — assembled into one API, one SDK, one MCP server. Wire it in, or have us wire it in for you.
Forward-deployed engineers wire Sonzai into your product.
Self-build with the SDK, or bring in our forward-deployed engineers — product engineering plus machine-learning expertise embedded in your codebase — whose only job is onboarding your application into Sonzai and maximising the relationship layer inside your product. Not a consultancy. We've shipped relational AI surfaces for consumer apps and $70M+ in AI value at DBS Bank. Most teams take many months building this themselves; with us, you can be in production in about a month.
A relationship that gets more personal every session.
Sonzai turns every conversation into durable relationship state. The agent doesn't just remember more. It feels more consistent, more emotionally coherent, more like someone who actually knows the user.
A live relationship graph under the agent.
The runtime keeps the messy human picture coherent: memories, personality traits, current mood, relationship history, and what changed since the last conversation.
Every turn updates who this user is to the agent.
What the user said, asked, felt, corrected
Voice, traits, boundaries, how the agent feels
Current emotional state, energy, valence
Preferences, history, milestones, inside jokes
Stage, trust, intimacy, what comes next
Relational AI, answered
Honest answers for teams building consumer AI companions, characters, avatars, and NPCs — and the engineers wiring them up.
Sonzai is the relationship layer for consumer AI agents — a managed platform that gives AI companions, characters, avatars, and NPCs persistent memory, personality, mood, relationship state, and model-agnostic orchestration through one API. Build with our SDK, or bring in our forward-deployed engineers to integrate the relational harness directly into your product.