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docs/features/offline.md

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+## Ofline routing on Android phones
+
+BRouter is first and foremost an offline tool. It runs on any Android phone. The
+online version offered here is just for a trial and for convenience. While many
+smartphone routing software use online services to do the actual route
+calculations, the advantages of the offline approach are evident:
+
+- It is more reliable, data connection problems and server-side problems are no
+  issue
+
+- It works in foreign countries where data connections are either not available
+  or very expensive
+
+- It does not raise any data privacy issues
+
+- You can use a cheap dedicated, second phone for navigation, without having to
+  put your business smartphone on an untrusted bike mount and run it's battery
+  low
+
+The downside is that advanced route calculations are difficult to do on a
+smartphone with limited computing and memory resources, which may lead
+developers to implement simplifications into the routing algorithm that affect
+the quality of the routing results. BRouter always does it's best on the
+quality, but has a processing time that scales quadratic with distance, leading
+to a limit at about 150km in air-distance, which is enough for a bikers daytrip.
+
+### Installing the BETA Version of BRouter on an Android smartphone.
+
+Before trying the Android app, you should have a look one the [online
+version](/brouter-web) to see what it's doing.
+
+What you should also do before trying the BRouter Android app is to install, an
+get familiar with, one of the supported map-apps. This is either
+[OsmAnd](http://www.osmand.net), which is a full offline navigation solution on
+it's own, but especially it's a wonderful offline OSM map tool and is able to
+give spoken directions to routes calculated either internally or externally.
+Other options are [Locus](http://www.locusmap.eu/) or
+[OruxMaps](http://www.oruxmaps.com/index_en.html).
+
+The BRouter Android app assumes that at least one of OsmAnd, Locus or OruxMaps
+is installed - it will not work otherwise.
+
+If you are o.k. with all that, you can install the BRouter Android app from the
+[brouter_1_6_1.zip](../brouter_bin/brouter_1_6_1.zip) installation ZIP-file
+including the APK and read the [readme.txt](readme.txt) ( **READ ME !** ) for
+details on how to add routing data and navigation profiles to your installation
+and how the interfacing between BRouter and the supported map-tools works.
+
+Navigation profiles and the lookup-data are [here](profiles2) Routing data files
+per 5*5-degree square are [here](/brouter/segments4)
+
+(The Map-Snapshot date is about 2 days before the timestamp of the routing data
+files)