Custos: Survival Prepper
Offline Emergency First Aid
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
Works with no internet, power, or signal: your offline guide for blackout, hurricane and earthquake. First aid, CPR, checklists and supplies, ready anytime.
What do you do when power, internet, and cell service all fail at once?
Custos is your offline companion built for exactly that moment. An app that needs no internet — because it has to work when nothing else does. Unlike any other emergency app: 100% offline, no cloud, no servers, no dependencies.
WHY CUSTOS?
In a blackout, flood, or earthquake, you don't just lose comfort — you lose access to every piece of information you rely on. Where's the nearest hospital? How do I treat a burn? How do I purify water? How do I survive 72 hours without power? Custos has the answers. Already installed, already there.
WHAT YOU GET:
▸ CRISIS SCENARIOS THAT GUIDE YOU THROUGH THE WORST
16 real-world emergencies (blackout, flooding, earthquake, storm, wildfire, pandemic, chemical spill, heat wave, evacuation, and more). Each scenario in 4 phases: what to do IMMEDIATELY, what to do in 24 hours, what to do long-term — and how to be better prepared next time.
▸ FIRST AID THAT SAVES LIVES
46 emergency topics with clear step-by-step instructions: CPR, heart attack, shock, burns, poisoning, fractures, stroke, crush syndrome, pediatric emergencies. Triage decision tree for mass casualty events. Help right when every second matters.
▸ SURVIVAL KNOWLEDGE THAT MAKES YOU INDEPENDENT
45 topics from crisis research and survival training: water purification, fire making, knots, Morse code, weather reading, navigation without GPS, backup power (solar, generator, EV), CBRN protection. Knowledge you can't find compiled anywhere else.
▸ CHECKLISTS THAT MAKE YOUR HOME RESILIENT
28 ready-made lists for emergency bag, pantry, first aid kit, document folder. Scales to your household size. You know exactly what you need — and what's still missing.
▸ OFFLINE MAPS WITH GPS
Download maps for your region — works without internet. GPS works without cell service. Always find the nearest safe location: hospital, police, pharmacy, shelter.
▸ MEDICATION DATABASE
Scan barcodes of your medications offline — 1.28 million entries in the German PZN database. Custos instantly shows active ingredient, dosage, expiration. Manages your home pharmacy with expiry alerts.
WHO IS IT FOR?
Parents protecting their family. Seniors living alone. Hikers and campers. People in regions with natural hazards. Anyone who doesn't want to find out they're unprepared during the actual emergency.
PRIVACY FIRST
No cloud. No tracking. No ads. Your data stays on your device. No account required.
OPTIONAL PREMIUM
Monthly €2.49 · Yearly €14.99 · Lifetime €24.99 one-time.
Free: 3 scenarios, first aid, emergency call, basic checklists. Premium: All 16 scenarios, offline maps, inventory tracking, family profiles, PDF export.
Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Terms & Privacy: https://holzbucht.de/pages/apple
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Improvements based on your feedback:
• Medications can now be edited and deleted directly from the person – just tap the entry.
• New medication units: syringe, drops and suppositories.
• Custom allergies are now saved reliably, even without tapping “+”. Adhesive plasters and iodine added to the list.
• You are now asked before unsaved changes are discarded.
Thank you for your feedback!
The developer, Emil Deak, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Linked to You
The following data may be collected and linked to your identity:
- Purchases
- Identifiers
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Location
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Emil Deak
- Size
- 172.9 MB
- Category
- Lifestyle
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
13+
- 13+
- Infrequent
Medical Treatment information
- In-App Purchases
Yes
- Custos Premium Lifetime $22.99
- Custos Premium Monthly $1.99
- Custos Premium Jährlich $12.99
- Copyright
- © 2026 Holzbucht - Emil Deak