We at Team KeyHub are excited to announce that we’re working on an innovation that’s been on our wishlist for a long time: a native KeyHub app for iOS and Android. The app is written in Dart (Flutter) and requires a solid communication layer to stay up to date with new versions of KeyHub. Microsoft Kiota, which we already use for other SDK’s, did not support Dart. Together with Kiota developers, other developers at Topicus, and external contributors, we wrote a Dart module for Microsoft Kiota. This is the first language added to Kiota that has been entirely developed by the community. This new Dart module is now available for everyone.
Native KeyHub App for iOS and Android
In 2024, we began realizing a long-desired goal: a native KeyHub app for iOS and Android. The app must be able to communicate with the KeyHub backend to process requests and access vault records.
The development of the app is in the hands of our partner Nerds & Company. The app is written in Dart (Flutter). Since the app does not directly interact with the KeyHub code but communicates via a REST API, an SDK is needed to make this communication easier and more efficient.
We faced a unique challenge. We had no way to generate a Dart SDK for KeyHub. Microsoft Kiota, which we used for other SDKs, did not have a Dart module and could not be used. We could write a one-time Dart SDK, but a generated SDK has the advantage of automatically staying up-to-date with new versions of KeyHub. This way, the app always stays in sync with the backend.
Synchronization between the native KeyHub App and backend
A key requirement for the communication layer is that it stays up-to-date with new versions of KeyHub without manual intervention. The ideal solution is for the necessary code to be generated automatically based on KeyHub’s REST API. With every update of KeyHub, this code can be regenerated, providing a maintenance-friendly solution.
To achieve this, a special Dart module was needed in Kiota. Since Team KeyHub did not have time to develop it themselves in the short term, we opted for collaboration within the Open Source Community. Together with other developers, we set up a project group to further develop the Dart functionality for Kiota.
The project group consisted of Team KeyHub, developers from Topicus Education (Kees Schotanus & Joanne ter Maat), an external developer from the Open Source Community (Ricardo Boss), and developers from Kiota.
Developing the dart module
Our wish was clear: an SDK for the REST interface of KeyHub, written in Dart, that can be automatically generated based on our OpenAPI specification.
KeyHub’s REST API already has an automatically generated OpenAPI specification, a standardized description of the API. Based on this specification, code generators can generate the required code to interact with the REST API. After some experimentation, we chose Kiota, an open-source code generator from Microsoft, which they also use to generate SDKs for their Azure Graph API.
We had good experiences with Kiota for our Golang SDK, which is used, among other things, by our Terraform provider. We wanted to build on this by also using Kiota for Dart.
Challenges in developing the Dart module
The development took place in the second half of 2024, mainly from August to November. The developers from Topicus Education had no experience with Dart, our target language, nor with .Net, the programming language in which Kiota is written. Nevertheless, they succeeded in close collaboration with the project team to write a Dart module for Microsoft Kiota within a few months. During this process, we encountered two major challenges:
Limited documentation
There was little documentation on how to add a new programming language to Kiota. Much of the knowledge had to be gained by analyzing existing code for target languages such as .Net, Java, and TypeScript.
Broad compatibility
The generated code had to work not only with KeyHub but also with third-party OpenAPI specifications. This required additional effort to fine-tune the SDK.
“I’m not easily proud of the code I write, but I’d find it pretty cool if third parties successfully use our code!”
Kees Schotanus | Software Developer | Topicus
Impact of the Kiota Dart Module
In 2025, the new Dart module was approved and accepted by the core developers of Microsoft Kiota. Thanks to Topicus, all Kiota users can now generate code in Dart.
For KeyHub, this means a robust, repeatable, and testable way to generate an SDK based on our REST specification. This keeps the native KeyHub app easily up-to-date with KeyHub itself.
This version of the Dart SDK is already being used in the KeyHub app, bringing the realization of the native KeyHub app closer. With this step, we are not only bringing the native KeyHub app closer to realization but also giving back to the Open Source Community. A win-win for everyone!
