Flutter SDK Engineer for Dart APIs and Mobile Auth

Anythink; United States; Remote; USD 90,000 - 150,000; Part time

Job summary

Anythink is seeking a contract backend engineer to create a Flutter SDK that is easy to use from Dart/Flutter apps. You will build and publish an idiomatic Dart SDK on pub.dev, covering authentication, file storage, and REST API access.

The role includes creating mobile-focused documentation and example applications, plus assisting customer integrations with Flutter. Requirements include production Flutter and Dart experience and publishing a Dart package to pub.dev.

Qualifications

• Production Flutter and Dart experience with apps released to App Store or Google Play.
• Experience integrating REST APIs from Flutter using http or Dio.
• Strong understanding of JSON serialization and asynchronous Dart patterns (Futures/Streams).
• Experience with iOS/Android deployment, provisioning, signing, release builds, and automated signing tools such as Fastlane.
• Experience publishing or maintaining a Dart package on pub.dev.

Responsibilities

• Develop and maintain a Flutter SDK package that wraps platform REST APIs.
• Implement authentication helpers for JWT handling, session refresh, and OAuth flows.
• Provide Flutter support for file uploads, downloads, and storage management.
• Build realistic example applications demonstrating common integration patterns.
• Write setup guides and documentation for mobile developers.
• Contribute to customer projects that integrate the platform with Flutter applications.

Skills

Flutter & Dart

REST APIs

JSON serialization

Futures & Streams

iOS/Android deployment

fastlane

Tools

pub.dev

http

Dio

fastlane

Job description

Anythink is seeking a contract backend engineer to create a Flutter SDK that is easy to use from Dart/Flutter apps. You will build and publish an idiomatic Dart SDK on pub.dev, covering authentication, file storage, and REST API access.

The role includes creating mobile-focused documentation and example applications, plus assisting customer integrations with Flutter. Requirements include production Flutter and Dart experience and publishing a Dart package to pub.dev.