Offline by design · Free and open source

Useful knowledge. Even without a connection.

Keep a library, practical Field Guide and private AI assistant on your iPhone, Android device or Mac. For a power cut, an emergency, or time off the grid. Answers from your library, with sources you can check.

Coming soon

AndroidComing soon to Google Play

Mac: coming soon

Read the survival guides →

For iPhone, Android and Mac. Downloads are in private testing and coming soon.

Zero Dark Fall / Library assistant

This Mac only · granite4.2:3b · Use the library

What is the best way to get around Lisbon?

The most efficient way to get around Lisbon is by using the metro and the extensive bus network, which together cover most neighborhoods and allow you to reach major attractions quickly. For shorter trips or a more relaxed pace, local trams, buses, or walking are also convenient.

Sources: [1] Lisbon · [2] Greater Lisbon · [3] Portuguese Way · [4] Lisbon/North

Three things, done well

Read, find and ask. Your library stays with you, even when the connection does not.

Read

An offline library

Wikipedia, Wiktionary, Wikivoyage, medical encyclopaedias and more, in the open ZIM format from Kiwix. Drop any .zim file in and it appears.

Zero Dark Fall is for reference only. It is not a substitute for professional medical care. In an emergency, call your local emergency number.

Find it as you type

Titles suggest as you type. A one-time index adds full-text search, and a local embedding model can re-rank results by meaning.

Ask

Answers with sources

On a Mac, chat with a local model through Ollama. Turn on "Use the library" and each answer lists the articles it drew on, with links you can check.

Choose your library

Start with what you need.

Download your content ahead of time. Choose a bundle that fits your device and the knowledge you want to keep close.

For iPhone & small devices

Essentials

3.86 GB

A starting point for smaller devices.

For desktop

Full

85 GB

A larger library to keep on your desktop.

Optional engineering add-on

Rebuild

18.6 GB

7.0 GB extra on top of Full.

Sizes shown are downloads. Android is coming to Google Play. Windows and Linux are planned.

Your knowledge stays yours.

On a Mac, Zero Dark Fall is built to run alongside your real work. These are not settings. They are how it is made.

No telemetryNo analytics, no crash reports, no usage pings. Not even optional ones.
Offline AI by defaultOptional online AI is off by default. If enabled, questions and library passages go to your chosen provider. See our privacy policy.
No accountsOffline AI needs no API key. Optional online AI uses your key, stored in your device’s secure keychain.
No auto-updateThe version you install is the version you run.
This Mac only, by defaultOn a Mac, it listens on 127.0.0.1. Sharing on your network is opt-in, over HTTPS, behind a password.
Every download checkedEach content pack is pinned to an exact file, size and SHA-256. Each model is pinned to its digest.
Models with open licencesOnly Apache 2.0 or similarly permissive models, listed in the source and built into the program.
Articles can't run codePages from content packs are shown with scripts, network requests and forms blocked.

For developers

Build it yourself

You need an Apple Silicon Mac (M1 or later) and Go to build it. For chat, install Ollama. The library and search work without it.

To start Zero Dark Fall at login, the repository includes a launch agent that runs as you. No sudo.

# build and install (no sudo)
$ git clone <source repository, coming soon> zerodarkfall
$ cd zerodarkfall && make install

# get a pack, index it, start
$ zerodarkfall fetch wikivoyage-en
$ zerodarkfall index --all
$ zerodarkfall serve
# open http://127.0.0.1:8740

Models it can use

Zero Dark Fall refuses any model that is not in its catalogue, even if Ollama has it. Every catalogue model has an Apache 2.0 licence.

Supported models and their uses
Model	Use	Maker
`granite4.2:3b` · `granite4.2:30b`	Chat	IBM
`mistral-small3.2:24b` · `devstral-small-2:24b`	Chat	Mistral AI
`gpt-oss:20b`	Chat	OpenAI
`granite-embedding:278m`	Search re-ranking	IBM