Offline maps

ApexGPS works without signal if the map tiles for the area are already on your phone. Two ways that happens: automatic caching, and manual pre-downloading.

Automatic caching

Anywhere you’ve looked at while you had signal is saved to your phone’s tile cache. Re-visit the same area offline → tiles load instantly from cache.

Cache is per tile-source — OpenTopoMap and Satellite are separate stores. Looking at an area in OpenTopoMap doesn’t help if you switch to Satellite offline.

Cache size shows in Settings → Storage with a per-source breakdown.

Manual pre-download (recommended for trips)

Before heading somewhere without signal, download the region deliberately:

Pick the area

Pan/zoom the map so the area you care about fills the screen.
menu → Maps → tap Download new area.
A small preview map shows the current area. Move it around to refine if needed.

Set the zoom range

A slider defines the zoom levels you want cached. Higher zoom = more detail but exponentially more tiles.

For a weekend hike: 10-16 is usually plenty.
For a major expedition / week-long trip: 10-17 or 10-18 if you want maximum detail.
Zoom 19+ is rarely worth it for outdoors — a lot of tiles, little extra info.

The UI shows the estimated tile count and MB size as you move the slider. Match against your free storage.

Download

Tap Download. A foreground notification appears; you can leave the app, lock the phone, whatever — the download continues. Progress updates live in the notification and on the Maps hub screen.

To cancel mid-download: go to the Maps hub → the download card has a Cancel button. (Pressing the back arrow does NOT cancel — that’s intentional so you can browse tracks while tiles download.)

Current tile source only

The download uses whichever tile source is active when you start it. To cache a different style, switch tile sources first (layers FAB on map screen), then initiate.

Every completed download shows here. Tap a region to open its detail screen:

Name — editable. Default is based on the country/region geocoded from the bounding box.
Tile source, zoom range, tile count, size on disk.
Show on map — closes the detail and zooms to the region’s bounding box.
Delete — frees the storage. With confirmation.

Deleting a saved region removes its tile bundle but does NOT affect the general tile cache. The area may still be cached from prior browsing.

Recipe rows (after restoring a recipe-mode backup)

Restoring a backup that was created with the Recipe offline-maps mode (see Backup → Recipe vs full tiles) inserts rows here marked “Not downloaded yet · X tiles” with a Download trailing button. Tap Download to re-fetch the tiles using the saved name, bounding box, zoom range, and tile source. The row flips to a normal saved-region row when the download finishes. If the recipe uses Thunderforest tiles and your API key isn’t saved, the app shows a one-time toast telling you to add it first under Settings → API Keys → Thunderforest.

Total cache size across all tile sources.
Per-source breakdown — how many MB each style occupies.
Clear all cache — nukes browse-cached tiles for every source. Does NOT delete your saved regions (they’re separate files).
Clear [specific source] — only that style’s browse cache.

Saved offline regions are managed separately on the Maps hub, not here.

What uses network on the trail

Even with everything cached, a few things may still try to reach the internet:

Switching tile styles if you haven’t cached the new style for that area — tiles will be blank.
Thunderforest (Outdoors) tiles are fetched with your API key over HTTPS.
Nothing else. Tracks, waypoints, and navigation are fully local.

If your phone has no signal, the Offline badge appears in the top bar. This is the device-level signal, not an app-level choice.

Tips

Always pre-download before a trip. Don’t rely on auto-cache — it only covers what you’ve actually looked at.
Two map styles can be helpful: OpenTopoMap for contours + paths, Satellite for visual reality. Download both for critical areas.
Higher zoom = more storage, diminishing returns. Past zoom 17 the extra detail rarely helps route-finding; it’s mostly building shapes and street labels.
Check free space before big downloads. A large region at zoom 18 can easily top 500 MB.