Flutter Sports Social App|Paid Refundable GPS Background Tracking Demo Required (Chinese Domestic Huawei/Xiaomi/Oppo/Vivo device you must own, 1-day d

We are building a sports and chatting app focused on online connecting users with workout partners (hiking, running, etc.). After Demo test passed, i will offer UI/UX design for you to start formal development. If you are also good at APP UI/UX design , we can negotiate extra fee for app UI/UX design which is not included in current bidding price. Current bidding price only obtains fee of demo and formal app development.

** NON-NEGOTIABLE FIRST STEP (Please Read Before Applying)
To ensure we are a match, we require a small, verifiable proof-of-concept before discussing budget or timeline. You will build a 100% offline Android demo app (no server/API needed) that implements:
1.Continuous GPS location collection
2.Real-time route/trail drawing on a map

Only candidates whose demo passes our background location stability test will continue developing the formal app. Demo must include source code, build instructions, and a short video demonstrating the background tracking working on locked-screen, background running and battery-saving modes of major Chinese Android devices (Huawei, Xiaomi, OPPO, Vivo).

* Offline Android Demo app Requirements:
The minimum tracking interval required is 5 seconds. We require continuous background tracking for at least 30 minutes, and the demo must maintain stable tracking without interruption under lock screen, background running, and battery saver conditions, verified on real android devices such as Huawei and Xiaomi . More Demo’s detailed requirements are shown below:

1. Moving state: location every 5 seconds
2. Stationary state: location every 15 seconds
3. Stationary = speed < 0.5 m/s; moving = speed ≥ 0.5 m/s
4. Apply this rule both indoor and outdoor, foreground and background/lock screen/Battery-Saving-Mode
5. Keep the log visible: state (moving/stationary), interval, timestamp, accuracy.
6. Demo app must running fluently on all android devices(ex. Huawei, Xiaomi, OPPO, Vivo)
7. use AMap (Amap) for demo

After demo test passed, the formal project of sports and chatting app is split into two phases:
** Project Overview
Phase 1: Core features include SMS login, LBS "Nearby Users", real-time IM (using NetEase Yunxin SDK), user profiles, and sports activity tracking.
Phase 2 (Advanced Features): Will be defined only after Phase 1 is successfully delivered and stable. The fee of Phase 2 is not included in current bidding price.

** Clarifications for Developers:

* Map Provider:
For users in China, we will use AMap (Amap) for route rendering.

* Backend & SDK Setup:
We already have NetEase Yunxin accounts ready. The Phase 1 backend will be built with PHP, and development must include full backend architecture setup, API design, database schema, and complete integration of the Yunxin SDK with our user system.

** Required Skills & Experience
1.Proven cross-platform development experience with Flutter for both iOS and Android.
Expert knowledge of Android background location policies, including vendor-specific restrictions (Huawei, OPPO, VIVO, Xiaomi, Honor).

2.Hands-on experience publishing apps to the Apple App Store and major Chinese Android app stores (Tencent App, Huawei, Xiaomi etc.), with a track record of stable long-term operation.

3.Experience integrating third-party IM SDKs (e.g. NetEase Yunxin) is a strong plus.

** How to Apply
In your proposal, please include:
1.A brief description of your experience with background location on Chinese Android/iOS devices.
2.Links to any relevant apps you have published (portfolio).
3.Confirmation that you are willing to build the offline demo as the first step.

** Timeline Expectation:
1.Demo prototype (offline GPS tracking only): within 1 business day
2.Full Phase 1 app development: No more than 30 days

** Payment Terms
1.The fee for the demo is $0. Funds shall be deposited into a third-party escrow account in advance.
2.All payments for formal phase 1 development and testing optimization shall be fully deposited into escrow account upfront.
3.Disbursement including demo fee will be authorized by the platform solely after all development documents (including source code, documentation, and assets etc) are verified and accepted, and the Phase 1 app is successfully launched and running fluently on All Android and iOS app stores.
4.If the demo does not meet the above "Offline Android Demo app Requirements", the freelancer shall revise it within 1 day. If the demo still fails acceptance after revision, or if we reach full acceptance of the demo but cannot reach an agreement to launch Phase 1 development, we reserve the right to cancel this demo milestone, and all escrowed demo funds shall be fully refunded to the employer.
5.If Phase 1 development fails to meet all acceptance criteria, the freelancer shall fix defects within 3 days. Only in cases of non-delivery or major breach may we request a refund of undelivered milestone funds.
6.All payment terms are non-negotiable. Any proposal requesting changes to escrow-based payment structure will be automatically rejected. Show More