We recommend using Zenodo to make data available to participants in your challenge. Like grand-challenge, Zenodo is open source, promotes Open Science, and it's free. Zenodo assigns a DOI to any data set you put on the platform. We have created a grand-challenge.org Community on Zenodo. If you add data for your challenge on Zenodo, please list your record in this community. In the future, we plan to more closely integrate Zenodo in grand-challenge.org.
We recommend you choose a permissive CC license for the data you share for your challenge.
A drawback of sharing your data via Zenodo is that a single repository on Zenodo may not exceed 50GB.
We have recently shared the first data set associated with a challenge on grand-challenge on the AWS Open Data Registry. This is a registry to discover and share datasets that are available via AWS resources. Data shared here can directly be accessed via AWS S3 and you can download them for free. The limitation of 50GB per repository that Zenodo imposes does not exist. If you want to add a dataset or example of how to use a dataset to this registry, please follow the instructions on the Registry of Open Data on AWS GitHub repository.
We're currently working on other solutions for datasets larger than 50GB, feel free to leave a message in the Forum.