GPS Background Tracking Module — React Native or Flutter

We are developing a B2B SaaS platform for field operations management. The platform uses a no-code frontend with a PostgreSQL backend on Google Cloud SQL. We need a mobile developer to build a lightweight GPS background tracking module. This module will record the field operator's location automatically at regular intervals and/or when the device enters a defined proximity radius around specific registered coordinates, without requiring any manual interaction from the operator. The module must integrate seamlessly with our existing app via deep links, so that from the operator's perspective the experience feels like a single application. --- **Scope of Work** The module must: 1. Run in the background on Android while the main app is open or the screen is off. 2. Record GPS coordinates automatically at a configurable interval and/or trigger a record when the device enters a defined radius (approximately 10–15 meters) around a set of known coordinates loaded from the backend. 3. Write each recorded point directly to a PostgreSQL table on Google Cloud SQL via a secure REST endpoint or direct SSL connection. The table schema and credentials will be provided upon project start. 4. Handle loss of GPS signal gracefully — queue records locally and sync when signal is restored. 5. Optimize battery consumption for field shifts of 4–8 hours. 6. **Register a custom deep link scheme** (e.g. `trackingapp://start` and `trackingapp://stop`) so the host app can: - Launch the module and pass session parameters (user identifier, session ID, and two additional reference IDs) when a shift starts. - Signal the module to stop and flush any locally queued records when the shift ends. The operator should never need to open the tracking module manually — it must launch and stop exclusively via deep links triggered by the host app. 7. Display a minimal persistent status notification ("Tracking active") while running, as required by Android for foreground services. --- **Technical Requirements** - Framework: React Native or Flutter (your choice — justify your preference in your proposal). - Target platform: Android (API 26+). iOS is a nice-to-have, not a requirement. - Backend: PostgreSQL 14 on Google Cloud SQL (SSL enabled). You will be given a read/write database user scoped to a single table only. Full schema details provided after NDA signature. - Deep link scheme: custom URI scheme (e.g. `trackingapp://`) with at minimum two intents: `start` (with parameters) and `stop`. Scheme name will be agreed upon at project start. - The module does NOT need its own UI beyond the mandatory status notification. All user interaction happens in the existing host app. - Code must be delivered clean, commented, and with a README explaining how to build, configure, and integrate it. - The deliverable can be a standalone APK or an integration-ready library/plugin — propose what makes more sense technically for deep link integration. --- **What We Are NOT Looking For** - A full app rebuild. We only need the tracking module. - A solution that requires the operator to manually open the tracking app to start or stop a session. - A solution that requires the host app to be open and in the foreground to record points. - Firebase, AWS, or any cloud intermediary — writes go directly to our PostgreSQL instance. - Monthly subscription services or third-party tracking SDKs with ongoing licensing costs. --- **Deliverables** 1. Working Android APK or integration-ready plugin/library with deep link support. 2. Source code (GitHub private repo, transferred on project completion). 3. README with build instructions, configuration parameters, deep link integration guide, and example of how to trigger start/stop from an external app. 4. Brief technical document explaining architecture decisions: background service approach, battery optimization strategy, deep link implementation, and geofencing if included. 5. One round of bug fixes after delivery and testing by our team (within 14 days of delivery). --- **Ideal Candidate** - Proven experience with background services and GPS tracking on Android (WorkManager, Foreground Services, or equivalent in Flutter). - Experience implementing deep link schemes and inter-app communication on Android. - Experience with geofencing APIs (Google Geofencing API or equivalent). - Direct database writes from mobile to PostgreSQL — not via Firebase or similar intermediaries. - Portfolio showing at least one field operations, logistics, or tracking app. - Clear written communication in English. Spanish is a plus. - Willing to sign a basic NDA before receiving technical details. --- **To Apply** Please include in your proposal: 1. Your preferred framework (React Native or Flutter) and why. 2. Your approach to background GPS on Android — specifically how you would handle Doze mode and battery optimization restrictions. 3. How you would implement the deep link scheme so the host app can start and stop the tracking session without the operator manually switching apps. 4. An estimate of hours and timeline. 5. At least one relevant project from your portfolio (tracking, field ops, geofencing, or inter-app communication). 6. Any questions about the technical requirements. Proposals without these items will not be considered.