> For the complete documentation index, see [llms.txt](https://docs.sign.global/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sign.global/for-builders/sdp.md).

# Sign Developer Platform

[Sign Developer Platform](https://developer.sign.global), or SDP, gives developers API access to various Sign Protocol services, such as paying for decentralized data storage.

### General Usage

Visit [Sign Developer Platform](https://developer.sign.global) and create an API key with the appropriate scopes. To fund the account balance to pay for API key usage, you can purchase credits with USDC (1 USDC = 100 Credits).

Once the account is properly funded, you can call the following API endpoints:

* Testnet: <https://testnet-rpc.sign.global/api>
* Mainnet: <https://mainnet-rpc.sign.global/api>

Make sure the proper header is attached in your API request:

```
Headers = {
	'x-sign-api-key': 'API key'
}
```

Alternatively, you can use our [SDK](https://www.npmjs.com/package/@ethsign/sp-sdk) (>= 0.9.7) which has been updated to work with API keys.

### Uploading Data to Decentralized Storage

To upload data to decentralized storage, use the following URL: `POST {endpoint}/sp/offchain-storage`

and request:

```json
{
    "storageType": 'arweave' | 'ipfs' | 'greenfield',
    "data": "your data"
}
```

The appropriate amount of fees will be deducted from the account. The total amount of fees paid is the sum of the base fee and size fee.

| Platform       | Base Fee | Size Fee (per byte) |
| -------------- | -------- | ------------------- |
| Arweave        | 0.01     | 0.0000000006        |
| BNB Greenfield | 0.01     | 0.00000000004       |
| IPFS           | 0.01     | 0.000000000002      |

*Please note the above fees may be adjusted without notice. All fee units are in Credits.*