**tldr: Second of three milestones in which SubQuery and Fearless Wallet create an open source API that should be able to provide different types of applications with a sufficient (but read-only) view of all key data within the Kusama chain. E.g. a developer could use it to create their own chain explorer without needing to directly query chain data**

We believe that the DApps ecosystem will benefit from a common core API that each parachain can integrate (and extend) to index and expose their chain data for future consumer facing applications (e.g. a wallet, explorer, or other dApp). 

There will be 3 individually proposed milestones delivering open source projects, packages, and associated learning material to help decentralised app developers start building applications on Polkadot/Kusama

**Who**

This is a joint proposal between two parties - SubQuery/OnFinality and Fearless Wallet/SORAMITSU

**What**
1. Create an Open-Source SubQuery Project for Common Data
2. Document and Publish Learning Material and Tutorials

**Outcomes**
1. Improve the Interoperability of DApps and Parachains
2. Attract and Support More Developers in Kusama

### Milestone 2

**This proposal is for the 2nd milestone only.**

Implement a SubQuery project that provides the data for the previously defined API spec for Kusama (from [milestone 1](https://kusama.polkassembly.io/treasury/95)).

Current API Spec GitHub: [https://github.com/subquery/common-api-polkadot/blob/main/schema.graphql](https://github.com/subquery/common-api-polkadot/blob/main/schema.graphql)
Current GraphDoc Preview: [https://subquery.github.io/common-api-polkadot/](https://github.com/subquery/common-api-polkadot/blob/main/schema.graphql)

It will be made open source (MIT license) on GitHub and uploaded to the SubQuery Explorer so it can be indexed and made available for all to query (for free).

Our view is that this API should be able to provide applications with a sufficient (but read-only) view of all key data within the chain. E.g. a developer could use it to create their own chain explorer without needing to directly query chain data. One key thing to note with our core API interface is that the design should largely work across any parachain. We’ve written it with existing parachains like Karura and Moonriver in mind.

You’ll see that there are some open issues in the repository. These APIs are intended to be constantly iterated and improved over time (with considerations to backwards compatibility). We invite the Kusama community to provide feedback directly via GitHub in the form of issues and pull requests.

[Please read full proposal here](https://docs.google.com/document/d/13L8HBwB6VB-n2g274FFFJKORYPJsq744C6H8iEDQ0-0/edit?usp=sharing)

- SubQuery and Fearless Wallet are working together to create an open source API for Kusama.
- The API will allow developers to access key data from the Kusama chain without directly querying the chain.
- This will improve the interoperability of decentralized applications (DApps) and attract more developers to Kusama.
- The second milestone is to implement the SubQuery project for the API.
- The API will be open source and available for free on GitHub and the SubQuery Explorer.

#332 Open-Source DApp API: Milestone 2