Custos: the offline crisis guide that still works without a signal.

view on the app store ↗ ios · iphone & ipad

Custos is the crisis guide that works exactly when everything else fails — completely offline, no cloud, no server, closer to sober preparedness than prepping or survival hype. First-aid instructions, checklists, offline maps and official warnings, all built to run without a network connection.

Sixteen scenarios, four phases each

Blackout, flooding, earthquake, storm, wildfire, pandemic, chemical incident, water or gas outage, heatwave, cold snap, supply shortage, evacuation, conflict, IT outage and emergencies abroad — sixteen disaster scenarios in total, each broken into immediate action (the first ten minutes), the first 24 hours, longer-term coping and follow-up. Together they add up to over 400 concrete steps.

First aid and knowledge, offline

46 first-aid guides with numbered steps cover situations from CPR and shock to burns, poisoning, sudden birth, panic attacks and child emergencies, backed by a triage decision tree. 45 further knowledge topics — knots, Morse code, reading the weather, navigating without GPS, water treatment, fire-making, backup power — come with a searchable glossary of terms, all available without a connection.

Maps, checklists and warnings

An offline GPS map, built on MapLibre, shows hospitals, police stations, pharmacies and shelters from OpenStreetMap data, downloadable in advance by region. 28 interactive checklists track your progress and export straight to a shopping list. A barcode scanner checks inventory and medication against a local database, and the app can pull alerts from 22 national and international warning sources — including NINA, USGS, MeteoAlarm, NWS and GDACS — when you open it or return to the warnings section.

• Guided seven-step emergency-call interview with GPS address lookup
• 221 emergency numbers worldwide, plus 48 German embassies abroad
• Family profiles: meeting points, a codeword, blood type, medication
• Notes, saved places and PDF export for all content
• Morse code camera and audio detector, sender, decoder and learning mode

Data and privacy

Custos asks for location only while it's in use (for maps and alerts, never in the background), for the camera (barcode scanning, Morse light detection) and the microphone (acoustic Morse detection). A scanned medicine is first checked offline against a local database of around 1.28 million entries; only if there's no match does a barcode go to an open database such as Open Food Facts. A local backup file with your data can be exported or shared, but only when you choose to. No adverts, no tracking, no cloud server for your content.

Full terms of use and privacy policy for all apps: Apps: terms & privacy.

More: all apps · what to do in an IT emergency.

Last updated: August 2026