# NDI Sender Discovery & Monitor

**NDI 6.3** expands the NDI SDK by introducing APIs for registering NDI senders, mirroring the functionality already available for receivers (*added in version 6.2*). These APIs enable sender discovery and monitoring when used with the [NDI Discovery Server](/all/getting-started/white-paper/discovery-and-registration/discovery-server.md). This new method does not break compatibility with the original sender advertising system (which we refer to as legacy senders advertisement); both will coexist. The key advantage of the new source advertisers is that they allow a listener to monitor most of their events and properties, a capability unavailable with the legacy method.

The NDI SDK now includes two additional header files:

* `Processing.NDI.SendAdvertiser.h` – Provides the API for advertising NDI senders within the Discovery Service, ensuring they can be discovered by other systems.
* `Processing.NDI.SendListener.h` – Offers the API for retrieving a list of advertised senders, enabling the monitoring of sender events.

These APIs provide a powerful method for discovering, monitoring senders in real time. The NDI Sender Advertiser API and NDI Sender Listener API are both included as part of the Standard SDK.

For more advanced functionality, the Advanced SDK includes additional APIs, such as:

* Sender Event Subscription – For monitoring sender events.

The full details of the Advanced APIs can be found in the manual under the section <mark style="color:red;">NDI Sender Event Monitoring</mark>


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