jack: private on-device ai

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In-app purchases

About this app

jack is a private ai assistant that runs entirely on your phone. download a model once, then chat fully offline. no cloud, no account, no tracking, no subscription. airplane mode works.

most local-ai apps stop at a chat box. jack is an assistant that does things:

• set timers and alarms
• draft texts and emails (you review before anything sends)
• start calls, search the web, get directions
• copy, share, flashlight, volume, do not disturb
• exact math via a built-in calculator (no model guessing)

every action is opt-in. you choose which actions are enabled, and you can require a confirm tap for each one.

your phone's real assistant
set jack as your device assistant and the assist gesture / power long-press opens it over whatever you're doing — like the built-in assistants, but private.

models, curated
a small catalog of good on-device models (qwen, gemma, phi) with device-aware recommendations: jack checks your phone's memory and warns you before you download a model it can't run well. downloads resume, survive navigation, and you can switch models anytime. all models are free.

private by design
• conversations are stored only on your device, encrypted at rest
• excluded from android backups — they never leave the phone
• no analytics, no crash reporting, no ads, no trackers
• the only network traffic is the model download you choose (and google play, if you buy pro)
• when you chat, zero network requests. verify it yourself in airplane mode.

the honest trade
on-device replies are slower than cloud chatbots — a few seconds, longer on phones with less memory. that's the cost of nothing leaving your phone. jack is tuned to make it as fast as your hardware allows.

jack pro (optional, one-time)
one payment, forever: agentic actions and advanced model tuning (engine, sampling, performance knobs). no subscription. chat and all models stay free.

jack of all trades, master of none — and it's yours, not rented.

What’s new

new: the tuned jack model. built for this app, it now sits at the top of the model list and is the recommended pick on most phones. it's best at taking actions, and at asking a quick question when it's unsure instead of guessing.

also in this update: more accurate recall of past chats (opt-in, under experimental), a calculator fix, settings reorganized into general / models / advanced, and a cleaner assist overlay.