> For the complete documentation index, see [llms.txt](https://circular-protocol.gitbook.io/standard-apis/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://circular-protocol.gitbook.io/standard-apis/api-docs/apis.md).

# APIs

In this section, we will delve into the details of communicating with the Circular Network. We'll learn how to structure various URLs for interaction with the distinct blockchains within the network.

## URL and Body Structure

The typical URL and body structure adheres to the following formats:

```json
URL = [NAG URL]Circular_[Network End Point]

Body = { 
"NAGKEY":[NAG KEY], 
"TBody":[Transaction body] 
}
```

Each NAG has a unique URL. Data is sent as a JSON payload through a POST HTTPS request. The payload contains the data that the NAG will send to the blockchain Network. When successfully executed, all endpoints will respond with a Result of 200, and the Response field will provide the required data or error details in JSON format.

The NAG URL for the Testnet is: <https://nag.circularlabs.io/NAG.php?cep=>\
For the Mainnet use: [ https://nag.circularlabs.io/NAG\_Mainnet.php?cep=](< https://nag.circularlabs.io/NAG_Mainnet.php?cep=>)