Maps and location

Google Maps Platform is split into products: Maps (the JavaScript API for the web, native SDKs for Android and iOS, static and embedded maps), Places (search, autocomplete and details for businesses and addresses), Routes (directions, travel times and route optimisation) and extras such as Street View, elevation and air quality. Every request uses an API key tied to a Google Cloud project with billing switched on, even when usage stays inside the free allowance.

Its strengths are data and familiarity: places, opening hours, reviews and address autocomplete are hard for other providers to match. Pricing is per request, grouped by product into Essentials, Pro and Enterprise tiers, each with a free monthly cap, while embedded maps and map loads in the mobile SDKs are free. The terms restrict caching results and showing Google data on non-Google maps, which makes mixing providers harder. Accounts in India have a separate, lower price list billed in rupees.

Mapbox serves vector tiles built largely from OpenStreetMap plus its own data, and its libraries (Mapbox GL JS on the web, native SDKs for Android and iOS) draw them on the device with WebGL. Maps can rotate, tilt and zoom smoothly, show 3D buildings and terrain, and take on any look designed in Mapbox Studio, from brand colours to hiding every label except roads. Geocoding, search, directions, matrix and navigation APIs cover the rest.

Billing counts web map loads (each time a map starts up on a page) and monthly active users in mobile apps, with large free allowances. Since version 2, Mapbox GL JS has used a proprietary licence and needs a Mapbox account even when showing other tiles; the community fork MapLibre GL JS stays open source and works with any vector tile provider.

Leaflet handles the essentials: panning and zooming, markers, popups, lines, polygons and GeoJSON layers, on desktop and touch screens. It fetches square image tiles from whichever tile server you name, so it has no map data or account of its own. Hundreds of plugins add marker clustering, heatmaps, drawing tools, search boxes and routing, and react-leaflet wraps it for React apps.

It is deliberately simple and weighs only a few dozen kilobytes. The trade-off is that it mainly shows raster tiles without WebGL, so smooth rotation, 3D and restyling a vector map in the browser are out of reach without plugins; MapLibre GL JS is the open-source option for those. The tiles are the part that can cost money: the public OpenStreetMap servers are for light use only, so production sites usually use a tile provider such as MapTiler, Stadia Maps or Thunderforest, or serve their own.

OpenStreetMap is a database of roads, buildings, paths, shops and boundaries that contributors add and correct, often from satellite imagery and GPS traces. The data is published under the Open Database License (ODbL): use it for anything, commercial work included, as long as maps credit '© OpenStreetMap contributors' and any modified version of the database you make public stays under the same licence. Mapbox, MapTiler and many other services build their maps from it.

The OpenStreetMap Foundation runs public tile servers and the Nominatim geocoder, but they are funded by donations and meant for light use: the usage policies require attribution, forbid bulk downloading and allow heavy users to be blocked without notice, and Nominatim allows at most one request a second. Apps with real traffic should use a tile provider built on OSM data or host their own tiles, for example with OpenMapTiles or PMTiles.

The world is cut into a grid at every zoom level: at zoom 0 a single tile covers the whole planet, and each level splits every tile into four, so street level at zoom 18 has tens of billions of them. A tile is addressed by zoom, x and y (the {z}/{x}/{y} in a tile URL), and panning a map just requests the next few tiles, which browsers and CDNs cache well.

Raster tiles are ready-made images, usually 256 pixels square, simple to show but fixed in style. Vector tiles carry the raw shapes and labels, and the device draws them with WebGL, so the map can be restyled, rotated and kept sharp at any zoom, usually with smaller downloads. Tiles come from providers (Google, Mapbox, MapTiler, Stadia Maps) or can be generated from OpenStreetMap data and served from your own storage, for example as a single PMTiles file.

Forward geocoding takes a typed address and returns a latitude and longitude, often with a tidied-up version of the address and a measure of confidence. Reverse geocoding goes the other way: a phone's GPS position becomes a street address. Address autocomplete is a close relative that suggests matching addresses as someone types, which cuts typos in delivery details.

Google, Mapbox, HERE and others offer geocoding APIs billed per request after a free monthly allowance, and each provider's terms say whether, and for how long, results may be stored; permanent storage is sometimes a separate, pricier product. Nominatim geocodes with OpenStreetMap data, free at low volume or on your own server. Address quality varies a lot by country, so it is worth testing with real addresses from your own market.

There are two common forms. On a server, a geofence is a polygon or a circle, and a point-in-polygon check answers questions such as 'is this address inside the delivery area?' at checkout; PostGIS, Turf.js and most map SDKs can do the maths. On a phone, the operating system watches for entry and exit (Android's Geofencing API, iOS region monitoring) and wakes the app when the device crosses a boundary, even in the background.

Device geofences have limits: Android allows 100 active geofences per app and iOS 20 monitored regions, alerts can arrive a few minutes late to save battery, and background location needs an extra permission that app stores review closely. Delivery zones drawn by postcode or by drive time (an isochrone) often match real delivery times better than a plain radius.

A routing engine treats roads as a graph with speeds, turn rules and, from some providers, live traffic, and finds the quickest path for driving, cycling or walking. A distance matrix returns travel times between many starting points and destinations at once, which is how an app finds the nearest driver or store. An isochrone shows everywhere reachable within a set time, such as 20 minutes.

Route optimisation is a harder problem: given 40 deliveries, 3 vans, time windows and vehicle capacities, find the order and split that minimises driving. It is known as the vehicle routing problem, a relative of the travelling salesman problem. Google's Route Optimization API and Mapbox's Optimization API solve it as a service billed by usage, while OSRM, GraphHopper, Valhalla and VROOM are open-source engines that run on OpenStreetMap data on your own servers.

In a browser, the Geolocation API (navigator.geolocation) asks the user for permission, works only on HTTPS pages and returns a latitude, a longitude and an accuracy radius in metres; watchPosition keeps updating as the device moves. On Android the Fused Location Provider blends GPS, Wi-Fi, mobile networks and motion sensors to balance accuracy against battery life, and on iOS Core Location does the same. Both let users share only an approximate position.

Accuracy ranges from a few metres outdoors with GPS to a whole neighbourhood from Wi-Fi or mobile networks alone, and is often worse indoors. Tracking in the background needs a separate permission and a clear reason, and app stores review it closely. Location from an IP address needs no permission but usually only gets the city or region right, which suits choosing a currency or language, not a delivery address.