Wikipedia, maps, medical references, and survival guides — all accessible from any device within Wi-Fi range, with no internet connection. Because knowledge shouldn't depend on a cell tower.
This guide covers the software and content side of offline knowledge hosting. For making the hardware run off-grid indefinitely, see The Solar-Powered Server. Combined with a Meshtastic mesh network for text communication, you have a complete community resilience stack that runs without any external infrastructure.
During extended outages — hurricanes, ice storms, wildfires, infrastructure attacks — internet access can be down for days or weeks. Cellular networks are fragile: towers need power and backhaul, and during a regional crisis, the surviving towers overload immediately with everyone trying to reach family. The internet doesn't "go down" as a monolith, but your access to it disappears when the last mile fails.
Meanwhile, the information you actually need in a crisis is finite and well-defined:
None of this information requires real-time updates. All of it is freely available. And all of it fits on a Raspberry Pi with room to spare. The absurdity is that we've routed access to this knowledge through fragile infrastructure when the knowledge itself is static and compact.
This guide sets up two core offline services: Kiwix for serving offline Wikipedia (and other ZIM-format content), and a tile server for serving offline OpenStreetMap maps. Both run on a Raspberry Pi, both are accessible via any browser on the local network, and neither requires internet after the initial download.
Kiwix is an open-source project specifically designed for offline content delivery. It reads ZIM files — highly compressed archives that bundle an entire website (HTML, images, search index) into a single file. The Wikimedia Foundation publishes official ZIM snapshots of Wikipedia in dozens of languages, updated roughly quarterly. Kiwix-serve turns a ZIM file into a web server that behaves exactly like the real Wikipedia — search, article links, categories, everything works. The only difference is the URL bar says 192.168.x.x instead of wikipedia.org.
This is the most important decision — storage is finite and ZIM files are large. Here's what's available and what each one gives you:
All 6.8M English articles, with images. Search, browse, everything. Requires a 128 GB+ SSD. This is the "real Wikipedia" experience.
Top ~100,000 articles by page rank. No images. Covers every major topic; misses niche articles and small-town pages. The sweet spot for most deployments.
Full article set, no images. Good compromise: all the text knowledge, half the storage of the full version.
Complete English Wikibooks — textbooks, how-to guides, manuals. First aid, knots, basic electronics, plant identification. Tiny storage footprint, outsized practical value.
Beyond Wikipedia, Kiwix hosts ZIMs for Wiktionary, Wikivoyage (travel guides), WikiHow, Stack Exchange archives, TED talks (video), and survival/medical reference packs. Browse the full library at library.kiwix.org.
☐ Wikipedia EN Mini (17 GB) — general knowledge
☐ Wikibooks EN (300 MB) — practical how-to
☐ Wikivoyage EN (700 MB) — regional travel/survival info
☐ Wiktionary EN (6 GB) — comprehensive dictionary
☐ iFixit Tech Wiki (1–2 GB) — repair guides for common devices
☐ Stack Exchange "Survival" export (50 MB) — wilderness survival Q&A
Total: ~25 GB — fits on a 64 GB SD card with room to spare, or barely notices a 256 GB SSD.
Kiwix-serve needs to start automatically when the Pi boots. A systemd service file handles this:
A text encyclopedia is half the equation. The other half is spatial: where is the water source? What's the fastest route to the community center? Where are elevation changes that might flood?
OpenStreetMap (OSM) is the Wikipedia of maps — community-maintained, freely licensed, and available as raw data you can host yourself. Unlike Google Maps, OSM's license permits offline hosting and the tooling ecosystem is built for it.
There are two approaches for serving offline maps, and they address different needs:
tileserver-gl renders OSM data into the familiar "slippy map" tiles your browser expects — exactly like Google Maps but from your Pi. It serves raster and vector tiles, styles them with Mapbox GL stylesheets, and presents a browsable, zoomable map in any browser.
Converting OSM data to mbtiles for a US state takes 1–3 GB of mbtiles output and about 30–60 minutes of processing on a Pi 5. A full US extract produces a 40–60 GB mbtiles file and may take 8+ hours. For most preparedness use cases, focus on your state + neighboring states (~5–10 GB total). Geofabrik provides per-state extracts; you don't need the whole planet. The Pi 5's 8 GB of RAM handles tile generation without swapping; a Pi 4 with 4 GB may struggle on larger extracts.
If the full tileserver-gl approach feels heavy, Organic Maps takes a different strategy: download OSM data directly to each phone, no server required. The Pi's role shifts from "render tiles" to "file server" — you host the map data files and people download them to their devices. Organic Maps is a free, open-source app (iOS/Android) that works fully offline once maps are loaded.
The advantage: no rendering load on the Pi, maps work when you leave Wi-Fi range, and the app handles routing/turn-by-turn. The disadvantage: each device needs its own download, and you need the Organic Maps app installed before the crisis (it's 60 MB — pre-install it on family phones as part of prep).
To make the map files available, host them via a simple file server on the Pi — Apache directory listing or a basic Python HTTP server. Include a README with install instructions for anyone connecting to the Pi's Wi-Fi for the first time.
With Kiwix on :8080 and the tile server on :8081, you need a simple landing page that ties them together. Anyone connecting to the Pi's Wi-Fi should see a clean directory of available resources. Create an index.html in the web root:
The technical setup is straightforward. The harder question is: what content do you include? Storage is cheap but not infinite, and during a crisis, curation beats completeness. Here's what I keep on my own offline Pi:
| Resource | Format | Size | Why |
|---|---|---|---|
| Wikipedia EN Mini | ZIM via Kiwix | 17 GB | General reference — answers "what is X?" for nearly any topic someone might need to research |
| Wikibooks EN | ZIM via Kiwix | 300 MB | First aid, knots, basic electrical, water treatment, plant identification — practical "how to" vs. Wikipedia's "what is" |
| State + Neighboring OSM | mbtiles | 5 GB | Maps of your region. Roads, water features, elevation, buildings. Navigation without GPS data connection |
| Local County PDF Maps | 100 MB | County-level parcel maps, flood zones, evacuation routes. Often available free from county GIS departments | |
| FEMA / Red Cross Guides | 50 MB | Official emergency preparedness and response guides. Free downloads | |
| Medical Reference | PDF / ZIM | 200 MB | "Where There Is No Doctor" (free PDF from Hesperian), basic pharmacology reference, wound care guide |
| Community Contact List | HTML / PDF | <1 MB | Names, radio call signs, mesh node IDs, physical addresses, skills inventory. Update quarterly |
Wikipedia contains 6.8 million English articles. During a two-week power outage, your community might need 500 of them. The right curation question isn't "what could someone possibly want to know?" — it's "what knowledge, if unavailable, would cause preventable harm?" Water purification, wound care, food safety, structural assessment after a storm, generator safety. Build the collection outward from those core needs, not inward from what's available.
ZIM files are published quarterly by the Wikimedia Foundation. Maps are updated daily on Geofabrik. Your offline content will drift from reality over time — roads get renamed, Wikipedia articles get corrections, new medical guidelines get published. The update cadence that makes sense:
An update script that downloads ZIMs and refreshes maps can run automatically when the Pi has internet — during normal grid-connected operation, let it keep itself current so it's ready when the grid goes down.
The system is useless if you discover a problem during a crisis. Run a "communications blackout drill" at least once a year:
The drill should take 15 minutes. It's the cheapest insurance you'll ever buy against discovering that your ZIM file was corrupted during the last download and you never noticed.
What's in your offline knowledge library? Share curation strategies, ZIM recommendations, or field experiences.