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How it works

A library that lives on your device.

RTW keeps knowledge in ordinary files on a device you own, and serves it as web pages — to that device and to anyone nearby on the same Wi-Fi. Here's what happens, without the jargon.

  1. STORAGEInternal storageexternal drive: planned
  2. HOST DEVICEMac or Androidruns the services
  3. LOCAL SERVERnginx + Kiwixhttp :8080 · https :8443
  4. LOCAL WI-FIHotspot or routerno internet needed
  5. CLIENTSPhones, laptopsa web browser
Each stage hands off to the next. Everything after the host device happens on the local network only.

What is an offline knowledge library?

It's a collection of useful material — an encyclopedia, books, maps, manuals, notes — copied onto a device so it can be used without any connection. You download it once, while you're online. After that, reading it never touches the internet.

How downloaded content is stored

As plain files in plain folders: one folder per section (Wikipedia, books, notes, maps, downloads, sites). Wikipedia and similar collections come as single compressed ZIM files from Kiwix; maps as a single PMTiles file; books as PDFs or EPUBs.

Because they're ordinary files, you can add or back them up with any file manager — nothing is locked inside a proprietary database.

How local access works

The device runs a small web server (nginx) alongside Kiwix's own server. You open the library in a browser at http://127.0.0.1:8080 — an address that always means “this device”. The pages, search and maps all load from local storage.

How offline Wi-Fi sharing works

Wi-Fi is a radio network between nearby devices. The internet is something a router may also provide — but it isn't required for devices on the same network to talk to each other. When a phone joins the host's hotspot and opens the library's address, the host answers directly.

How sharing worksA host device stores the knowledge library and runs a small local web server. Nearby phones, laptops and tablets connect to it over local Wi-Fi and read the library in a web browser. No internet connection is involved.HOST DEVICEMac or AndroidKnowledge libraryZIM · PDF · mapsstored locallyLOCAL SERVERWeb pages on :8080LOCAL WI-FIhotspot or routerPhoneany browserLaptopany browserTabletany browserno internet needed

The difference between a reader and a local server

A reader

An app that opens offline content on one device, for one person — like the Kiwix app reading a ZIM file.

A local server

One device holds the content and serves it to many. Readers need nothing but a browser. This is what RTW sets up.

Supported device architectures

  • macOS on Apple Silicon or Intel — available from source, tested on Apple Silicon.
  • Android on 64-bit ARM (arm64-v8a) through Termux — available from source, tested on a Redmi Pad 2 Pro.
  • Readers: any device with a reasonably modern web browser, including older phones.

Optional external storage

Large collections can outgrow internal storage, so keeping a library on a USB-C drive is a natural idea. Whether it works depends on the device's USB-C support, the drive's filesystem and Android's storage permissions — Android in particular restricts where apps may write on removable media.

Not supported yet. External storage hasn't been tested on either platform. What's known so far.

Common operating limitations

  • The host has to stay on and awake while others use it.
  • Android may stop background apps to save battery — Termux needs “No restrictions”.
  • Range is limited to the Wi-Fi network, typically a room or a building.
  • Content is a snapshot: it doesn't update until you download a newer copy.
  • Browsers only share location with HTTPS pages, so map location on other devices needs a one-time certificate warning.

The importance of backups

A library on one device is one dropped phone away from gone. Copy your content folder somewhere else — another drive, another computer, a second device. Some sources change or disappear over time, so your copy may become the only one you can get. Backup & Recovery.