🌊 Fully offline · iPhone 15 Pro or later · Coming to iOS

Your AI companion lives on your phone, not in the cloud.

Nudii is a virtual nudibranch sea slug powered by AI that runs entirely on your iPhone. No chat servers. No subscription to start. Your conversations stay on your device.

Be the first to know when Nudii launches.

Waitlist emails are handled by Formspree for this website. The Nudii app itself keeps your conversations on your device.

See how it works
Sea Bunny nudibranch
"The deep sea is calling. How was your day?"

🔒 Your conversations never leave your phone.

Nudii runs a 2.3 billion parameter AI model entirely on your device. No cloud servers for chats. No account required. What you share with your nudii stays with your nudii.

How It Works

Private by design. Emotional by design too.

We keep the public story focused on what matters to players: the relationship, the privacy model, and the shape of the experience.

1

Hatch a real nudibranch species

Start with one of two free species, hatch your nudii from an egg ribbon, and name a companion that feels personal from day one.

2

Talk, care, and build memory

Conversations, care rituals, mini-games, and optional HealthKit activity all shape how your nudii responds and what it remembers.

3

Grow through a full life cycle

Your nudii evolves from Egg to Veliger, Juvenile, Adult, Mythic, and eventually Departed. Mythic is earned through time, not purchased.

4

Keep everything on your iPhone

The app is built around on-device AI and local storage, which is why it needs newer hardware and a larger download than a typical pet app.

Features

A companion that actually remembers you.

Built on real marine biology and real on-device AI — not a chatbot with a cute skin.

On-Device AI

Powered by Google's Gemma model running entirely on your iPhone 15 Pro or later. Your conversations are never sent anywhere — not to us, not to anyone.

Long-Term Memory

Your nudii remembers what you've talked about and brings it up naturally. It builds a real picture of your life over time — all stored locally on your phone.

Genuine Evolution

Six phases over roughly a year — Egg, Veliger, Juvenile, Adult, Mythic, and Departed. Each phase changes the relationship. Mythic must be earned; it can't be bought.

Rare Mood Days

About once a week, your nudii enters a special mood — Philosophical, Extra Playful, Mysteriously Quiet, or Glowing. It changes every interaction for that full day.

Interactive Care

Feed it, clean it, put it to sleep, and play six retro mini-games with it. Real-world steps and workouts via HealthKit earn your nudii bonuses.

Species-Specific Music

Every nudibranch species has its own AI-generated music track — Latin Pop, K-Pop, Afropop, Kawaii, Cinematic, and more. All original and copyright-free.

Species

8 real nudibranchs. 8 unique personalities.

Each species is based on a real nudibranch — with real biology informing how they act, what they say, and how they grow. Two species are free to start; six more are available as one-time purchases.

Free Spanish Shawl nudibranch

Spanish Shawl

Violet body, orange cerata. Fiery and expressive.

Free Anna's Chromodoris

Anna's Chromodoris

Electric blue, orange rhinophores. Bold and inquisitive.

Premium Opalescent nudibranch

Opalescent

Iridescent stripes with glowing tips. Dreamy and quiet. $1.99

Premium Four-Color nudibranch

Four-Color

Purple, white, orange, and black bands. Proud and eccentric. $1.99

Premium Sea Bunny nudibranch

Sea Bunny

Fluffy white with ear-like rhinophores. Playful and warm. $2.99

Premium Blue Dragon nudibranch

Blue Dragon

Pelagic blue and silver wings. Wandering and wild. $4.99

Premium Spanish Dancer nudibranch

Spanish Dancer

Massive and crimson, a swimmer. Passionate and dramatic. $3.99

Premium Black Nembrotha nudibranch

Black Nembrotha

Black body, emerald crests. Brooding and deeply loyal. $2.99

Evolution

One year. Six phases.

Your nudii grows and changes over time. The Mythic stage cannot be purchased — it must be earned through a year of care and conversation.

Egg

Egg

3 days

Veliger

Veliger

7 days · baby talk

Juvenile

Juvenile

~60 days · curious

Adult

Adult

~90 days · full bloom

Mythic

Mythic ✦

~120 days · earned only

Departed

Departed

One final farewell

Environments

Seven aquariums. One comes free.

Give your nudii a home that suits them. Each environment has its own mood and atmosphere.

Open Ocean
Open Ocean FREE
Coral Reef
Coral Reef $1.99
Deep Sea
Deep Sea $1.99
Kelp Forest
Kelp Forest $1.99

+ Tide Pool ($1.99), Hydrothermal Vent ($2.99), and Shipwreck ($2.99) available in-app.

Pricing

Free to start. Deeper if you want it.

No ads. No attention tricks. No dark patterns. Just a companion app with an honest price.

Starter

Free

$0

Everything you need to hatch, raise, and love a nudii — with no time limit.

  • Full lifecycle (Egg → Mythic → Departed)
  • Unlimited AI conversations
  • Up to 50 long-term memories
  • 2 starter species (Spanish Shawl & Anna's Chromodoris)
  • All care mechanics and mini-games
  • HealthKit integration

Subscription

Deep Diver

$3.99 /month

For those who want their nudii to remember everything, live longer, and sound extraordinary.

  • Unlimited long-term memories
  • Revival — bring back a departed nudii
  • Mythic stage extension
  • All music tracks and premium neural voice
  • All aquarium environments

Also: $24.99/year — save 47%

One-time

Add-ons

From $0.99

Optional extras — none required to enjoy a full Nudii life.

  • Premium species: Opalescent, Four-Color, Sea Bunny, Blue Dragon, Spanish Dancer, Black Nembrotha
  • Aquarium environments: Coral Reef, Deep Sea, Kelp Forest, Tide Pool, Hydrothermal Vent, Shipwreck
  • Decorations and special foods
  • Stage Boost (Mythic excluded)

FAQ

A few honest answers up front.

The product is unusual, so the website should answer the unusual questions directly.

Why does Nudii need an iPhone 15 Pro or later?

The AI model runs on the phone itself instead of on a server. That privacy-first approach needs more RAM than older iPhones reliably provide, so we’d rather be clear than over-promise.

Why is the app around 2.5 GB?

Because the model and artwork live with the app. The size is a tradeoff: larger download, but no cloud dependency for conversations.

Is everything completely offline?

Your chats, memories, and pet state are designed to stay on-device. Purchases are handled by Apple, optional website waitlist signups are handled separately, and support/privacy emails obviously reach us when you contact us.

Can I get a departed nudii back?

Yes. Deep Diver Premium includes revival. The farewell still matters, but the relationship does not have to end there if you want to continue it.

Privacy Policy

The app is private by default. The website only receives what you intentionally send us.

Last updated: April 2026

Nudii is designed from the ground up to be private. The app’s AI model runs on your device, and your conversations, memories, and pet data are stored locally using Apple’s frameworks instead of being sent to our servers.

App data stored on your device

The Nudii app stores the following data locally on your device. We do not use our own cloud backend to receive or store this information:

  • Your name — entered during onboarding to personalise AI responses. Stored on-device only.
  • Conversation history — all chat messages with your nudii. Stored locally, used by the on-device AI for context. Never transmitted.
  • Pet state — your nudii's name, species, stats, and evolution stage. Stored via SwiftData.
  • Health data (optional) — if you grant HealthKit access, Nudii reads your step count and workout data to award your nudii bonuses. This data is read-only, never written back, never transmitted, and never retained between sessions.
  • Speech data (optional) — if you use voice input, audio is sent through Apple’s speech recognition APIs for transcription. We do not store those recordings on our own servers.

Website and contact data

If you join the waitlist, email support, or email privacy, you are intentionally sending contact information through website or email providers so we can respond. That is separate from the in-app privacy model.

In-app purchases

All purchases are processed by Apple via StoreKit 2. We do not receive, process, or store any payment information. Apple's privacy policy governs all transactions.

Analytics and advertising

Nudii contains no advertising SDKs and no third-party tracking inside the app. There are no ads in the app.

Children's privacy

Nudii is intended for users aged 13 and over. As the app collects no data whatsoever — all conversations, memories, and pet data stay on your device — there is no mechanism by which we could collect or access information from any user, including minors.

Data deletion

All data is stored on your device. To delete all Nudii data, uninstall the app. Everything goes with it — there is no server-side copy.

Changes to this policy

We will update this page if our privacy practices change. Continued use of the app after any update constitutes acceptance of the revised policy.

Contact

Questions about privacy? Email privacy@nudii.app.

Support

Need help? We've got you.

Nudii is an independent app. We read every support email and aim to reply within 48 hours.

📧 Email Support

For bug reports, questions, or anything else — email us directly. Include your iOS version and device model if you're reporting a bug.

support@nudii.app →

🔒 Privacy Questions

Questions about how the app handles your data, HealthKit integration, or anything related to privacy.

privacy@nudii.app →

💳 Purchases & Billing

All purchases are processed by Apple. For billing issues or refund requests, visit Apple's support page or manage subscriptions in Settings.

Apple Support →

❓ Quick Answers

Why is the app 2.5 GB? The AI model lives entirely on your phone — that's what makes it private. It needs space to be smart.

Can I recover a departed nudii? Yes, with Deep Diver Premium you can revive a departed nudii.