# Marketplace API overview for publishers

The Marketplace API provides resources for users to browse, install, and manage Listings. Listing Partners can use Marketplace API resources to retrieve and update Listings, and to manually report customer usage.

## Base URL

All relative URLs in the Marketplace API reference documentation use the following base URL:

```bash
https://marketplace.twilio.com/v1
```

The API is served over HTTPS. To ensure data privacy, unencrypted HTTP isn't supported. All responses are in JSON format.

## Authentication

To authenticate requests to the Twilio APIs, Twilio supports [HTTP Basic authentication](https://en.wikipedia.org/wiki/Basic_access_authentication). Use your *API key* as the username and your *API key secret* as the password. You can create an API key either [in the Twilio Console](/docs/iam/api-keys/keys-in-console) or [using the API](/docs/iam/api-keys/key-resource-v1).

**Note**: Twilio recommends using API keys for authentication in production apps. For local testing, you can use your Account SID as the username and your Auth token as the password. You can find your Account SID and Auth Token in the [Twilio Console](https://www.twilio.com/console).

Learn more about [Twilio API authentication](/docs/usage/requests-to-twilio).

## Response codes

The following table lists some common scenarios along with associated HTTP response codes, Twilio Debugger notifications, and messages that the Marketplace API returns.

| **HTTP response code** | **Debugger notification** | **Description**                                                                                                         |
| ---------------------- | ------------------------- | ----------------------------------------------------------------------------------------------------------------------- |
| 404                    | Warning                   | The Add-on isn't installed on the customer account or no Listing is found with the Installation SID.                    |
| 403                    | Warning                   | The Account Sid in the API request doesn't match with the Partner Account Sid attached to the Add-on.                   |
| 403                    | Warning                   | The Add-on isn't set up to accept [Manual Usage Reporting](/docs/marketplace/api/installed-add-ons-usage#prerequisite). |
| 403                    | Warning                   | The Add-on isn't in one of the Marketing Preview, Private Beta, or Active state.                                        |
| 400                    | Warning                   | Quantity is either null, empty, or 0.                                                                                   |
| 500                    | Error                     | Error received while generating a billing event.                                                                        |
| 202                    | N/A                       | The request is successful, and a billing event is generated.                                                            |

## API resources

The Marketplace API includes the following resources for Marketplace Listing publishers:

| Resource                                                                  | Description                                                     |
| ------------------------------------------------------------------------- | --------------------------------------------------------------- |
| [Listing](/docs/marketplace/api/listing)                                  | Get or update published Marketplace Listings.                   |
| [Installed Add-ons Usages](/docs/marketplace/api/installed-add-ons-usage) | Manually report customer usage for your own published Listings. |