How do I add turn-by-turn directions and ETA estimates to a delivery app?

To add turn-by-turn directions and ETA estimates to a delivery app, you generally need three pieces:

1. A map rendering SDK to show the map
2. A routing/directions service to calculate a route and steps
3. A live location tracking system to keep the driver’s position updated and re-route when needed

1) Choose a maps provider

Common options:

• Google Maps Platform
• Mapbox
• HERE
• Apple MapKit (best for iOS-specific apps)

Most delivery apps use Google Maps or Mapbox because they support:

• turn-by-turn routes
• traffic-aware ETAs
• geocoding/reverse geocoding
• route rerouting

2) Show the map and driver/customer locations

You’ll need to:

• display a map in the app
• place markers for:
  • driver current position
  • pickup location
  • dropoff location
• update the driver marker as GPS data changes

On mobile, you typically use:

• iOS: Core Location + map SDK
• Android: Fused Location Provider + map SDK

3) Request a route from the directions API

When you have:

• origin = driver current location
• destination = delivery address

Call the provider’s Directions API to get:

• route polyline
• step-by-step instructions
• distance
• duration / ETA
• optional traffic-aware duration

Example response data usually includes:

• steps: “Turn left on Main St”
• distance
• duration
• overview polyline

4) Display turn-by-turn navigation

There are two approaches:

A. Embedded navigation UI

Use the provider’s navigation SDK so the app shows:

• route line
• next turn
• voice prompts
• automatic rerouting

This is easiest for a true driver navigation experience.

B. Custom navigation UI

You build your own UI using the route steps returned by the directions API:

• show the route on the map
• display next instruction at the top
• highlight current step
• use text-to-speech for voice prompts

This gives more control, but requires more work.

5) Calculate ETA

ETA is usually derived from the route duration plus live traffic.

Typical formula:

• ETA = current time + route duration
• if using traffic, use the API’s duration_in_traffic or equivalent

For better accuracy:

• recalculate ETA when the driver deviates from the route
• update ETA every 15–60 seconds
• consider stop time, traffic, and delivery dwell time

6) Re-route dynamically

Drivers often miss turns or face traffic. You should:

• compare GPS updates against the current route
• detect off-route behavior
• request a new route if needed
• update ETA accordingly

7) Backend architecture

A common flow is:

• Driver app sends GPS location to backend every few seconds
• Backend stores current driver location
• Backend can call directions service for ETA
• Customer app receives live tracking via WebSockets / Firebase / push updates
• Delivery status updates are synced between driver, customer, and dispatcher

8) Important implementation details

Performance

• Don’t call routing APIs too frequently
• Throttle location updates
• Cache route data when possible

Battery usage

• Use adaptive location tracking
• Increase accuracy only when active navigation is needed

Permissions

Request:

• location while using app
• background location if navigation continues with screen off
• notifications if you provide arrival updates

Legal/licensing

Some map providers restrict:

• storing route data
• displaying turn-by-turn guidance without their SDK
• using data outside approved use cases

Read the provider’s terms carefully.

9) Typical tech stack example

Mobile app

• Flutter / React Native / native iOS / native Android
• Google Maps SDK or Mapbox SDK

Backend

• Node.js / Python / Go
• PostgreSQL + Redis
• WebSockets or Firebase Realtime Database for live tracking

APIs

• Geocoding API
• Directions API
• Distance Matrix / Routes API
• Traffic-aware ETA service

10) Recommended approach

If you want the fastest path:

• Use Google Maps Platform or Mapbox
• Use their directions + navigation SDK
• Stream GPS updates from driver app
• Compute ETAs from traffic-aware route durations
• Re-route on deviation

If you want, I can also give you:

1. a step-by-step implementation plan,
2. sample code for Flutter/React Native/iOS/Android, or
3. a recommended architecture for a delivery app with live driver tracking.