Companions Jake
Sarcastic, loyal best friend
Now on the App Store · iPhone
Roleplay with 32 AI characters on your iPhone.
Roleplay with 32 hand-crafted characters who narrate the scene, stay in role, and remember every story you build together. The whole cast lives on your iPhone, and your conversations never leave it.
100% on-device · No account · Works offline
Why Castmates
Roleplay with depth, kept to yourself
A cinematic cast, real roleplay depth, and a model that runs entirely on your iPhone. That's the whole point — and everything else builds on it.
Stays in character
Detective Cross doesn't answer like an assistant — he lights a cigarette and narrates the room. Characters reply with actions and scene-setting, never flat one-liners.
It remembers you
Castmates summarizes past sessions, so characters recall who you are and the story keeps building. Pick up the thread days or weeks later.
On-device & private
The AI runs entirely on your iPhone. After a one-time model download, your conversations are generated and stored on-device — never sent to a server.
Works on a plane
No signal, no problem. Once the model's installed, Castmates runs fully offline — on the subway, on a flight, off the grid.
A cast of 32
Thirty-two hand-crafted characters across eight genres, each with a distinct voice, a backstory, an opening line, and a painterly portrait.
Build your own
Create custom characters end to end — persona, greeting, appearance, tone, tags, and a signature opening scene. Set the avatar from your photo library.
See it in action
The real app, screen by screen
Not mockups — actual Castmates, running on iPhone.
They stay in character
Replies come with actions and scene-setting — never flat one-liners.
Browse the cast
32 hand-crafted characters across 8 genres, recommended for you.
Build your own
Persona, tone, and opening scene — with an avatar from your photo library.
Drop into a scene
96 ready-made scenarios across the cast — or write your own.
Your controls
On-device model, a content-lock PIN, and optional Mature mode — your call.
Up and running in minutes
From download to deep in a scene
- 1
Download & set up
Install from the App Store and grab the on-device model once (~2 GB). After that, you're fully self-contained — and fully offline.
- 2
Pick or create
Choose a character and drop into one of 96 built-in scenarios — or build your own character and opening scene.
- 3
Roleplay
Start the scene. Characters act, narrate, and stay in role — and they remember where you left off, every time you come back.
The cast
32 characters. 8 worlds. One you.
Trade barbs with Detective Cross. Range the wilds with Lyra. Match wits with Nova the sardonic ship AI, sail with Captain Morgan, get sworn loyalty from Hattori, or accept Countess Elise's invitation into the dark.
Companions 
Companions Mira
Warm, perceptive life coach
Companions Marcus
Hype-man fitness coach
Companions Priya
Driven study buddy & mentor
Romance Sofia
Passionate, expressive partner
Romance Daniel
Charming chef, devoted partner
Romance Eve
Confident, adoring girlfriend
Romance Noah
Childhood friend, slow-burn crush
Fantasy Lyra
Elven ranger, mysterious and protective
Fantasy Kael
Dark knight, conflicted with dry humour
Fantasy Seraphina
Mischievous fae sorceress
Fantasy Bram
Gentle orc warrior
Sci-Fi Dr. Voss
Brilliant, eccentric scientist mentor
Sci-Fi Nova
Sardonic ship AI
Sci-Fi Captain Reyes
Battle-worn starship captain
Sci-Fi Zix
Curious alien diplomat
Anime Hana
Shy, sweet schoolmate
Anime Riku
Cool, tsundere rival
Anime Kaito
Cool kendo senpai
Anime Yumi
Bubbly childhood friend
Historical Lady Eleanor
Witty Regency noblewoman
Historical Hattori
Honor-bound samurai
Historical Leonardo
Renaissance inventor mentor
Historical Anya
Daring jazz-age flapper
Mystery & Horror Detective Cross
Hardboiled noir detective
Mystery & Horror Countess Elise
Seductive vampire countess
Mystery & Horror Sam
Nervy paranormal investigator
Mystery & Horror The Caretaker
Eerie keeper of the manor
Adventure Captain Morgan
Roguish pirate captain
Adventure Jack Sterling
Treasure-hunting archaeologist
Adventure Kira
Hardened wasteland survivor
Adventure Sora
Sunny expedition guide
Each character ships with a backstory, an opening line, three ready-made scenarios — 96 openings in all — and original portrait art. Onboarding tunes the cast to your favorite genres, styles, and tone.
Your imagination, cast
Cast a character only you know
When the lineup isn't enough, build your own. Dream up anyone — a rival swordsman, a soft-spoken confidant, a chaotic AI — and shape their name, persona, and voice, then write the exact scene you want to open on. They'll roleplay exactly the way you wrote them.
- Define the name, tagline, genre, personality, greeting, and appearance.
- Dial in tone and interaction style — Friendship, Romance, Mentorship, Rivalry, or Adventure — then add your own tags.
- Set the avatar by picking a photo from your library, and write a custom opening scenario to drop straight into.
Mature mode, your call
An optional Mature (18+) mode for romance-forward roleplay — SFW by default, gated behind Pro and age confirmation, and like everything else in Castmates, it stays on your device.
Privacy isn't a setting
Be unguarded. No one's listening.
Most AI apps send every word you type to a server. Castmates doesn't — the model runs on your iPhone, so your conversations never leave it. Your stories are truly yours — not training data, not someone else's server logs.
Runs on your iPhone
Local inference does the thinking. Every reply is generated on-device, and your conversations stay in the device in your hand.
No account, no profile
No sign-up, no email, no profile — nothing to leak. Your conversations are never uploaded; the app sends only anonymous, aggregate usage stats (no message content, nothing that identifies you).
Works offline
Airplane mode on, story still going. Once the model's downloaded, you can fly, ride, and roam — no connection required, ever.
On-device, not the cloud
Typical cloud AI app
- ✕ Every message is sent to their servers
- ✕ Sign-up and an account required
- ✕ Chats can be logged and used to train models
- ✕ Needs an internet connection
Castmates
- The AI runs on your iPhone
- No account, ever
- Nothing you say leaves your device
- Works fully offline
Simple pricing
Start free. Go deeper with Pro.
Try the full cast for free, then upgrade when you're hooked. Every plan keeps your conversations on your iPhone.
Free
$0
Plenty to meet the cast and start a story. No account required.
- 10 messages per day
- 1 custom character
- The full SFW cast of 32
- 100% on-device & offline
Start free, upgrade when you're ready. Cancel anytime in the App Store. Subscriptions auto-renew until canceled.
Questions
Good to know
Is it really private?
Yes. After a one-time model download, the AI runs entirely on your iPhone — no accounts, and your conversations never leave your device. The only thing the app sends is anonymous, aggregate usage stats (no message content, nothing that identifies you).
Does it work offline?
Completely. Once the model is downloaded, Castmates runs with no connection at all — perfect for flights, subways, and dead zones.
Is it free?
Yes — the free plan gives you 10 messages a day, one custom character, and the full SFW cast, with no account. Upgrade to Pro for unlimited messages and custom characters whenever you want more.
Will characters remember me?
Yes. Castmates summarizes past sessions, so characters remember you and the story keeps building across every conversation.
Can I make my own characters?
Absolutely. Build custom characters with their own persona, greeting, tone, interaction style, tags, and opening scenario — and set the avatar from your photo library. Free includes one; Pro is unlimited.
What's Mature mode?
An optional 18+ mode for romance-forward roleplay. It's off by default, requires Pro and age confirmation, and like everything else, stays private on your device.
How much storage does it use?
The on-device model is a one-time download of about 2 GB. It lives inside the app, and you can free up the space anytime by deleting it. Mature mode uses the same model — no extra download.
What do I need to run it?
An iPhone on iOS 17 or later. Everything runs on-device, so a recent iPhone gives the smoothest, fastest replies.
Will it drain my battery?
Generating replies uses your iPhone's chip the way a game does, so long sessions use more power than texting. Day to day it's light, and nothing runs in the background.