# Backend Clients interact with Qualcomm® AI Engine Direct through backends. In general terms, a Qualcomm® AI Engine Direct backend is a software entity that implements [QNN API](https://docs.qualcomm.com/doc/80-63442-10/topic/general_api.html), and is typically compiled in the form of a shared library. The terms *QNN backend* and *QNN backend library* are often used interchangeably. QNN backend libraries provide integration modularity per hardware accelerator core (see [Overview](https://docs.qualcomm.com/doc/80-63442-10/topic/QNN_general_overview.html) for more details). The QNN SDK provides several backend libraries. These libraries can be found in `/lib/` folders. QNN backend libraries follow naming rules that are platform dependent (see Platform Differences for more details). In the [Available Backend Libraries table](https://docs.qualcomm.com/doc/80-63442-10/topic/backend.html#qnn-sdk-backends-table) Library Description, the backend library is referred to by its platform agnostic name. **Available QNN SDK Backend libraries** | Backend Name | Backend Description | Target and Library Names | Library Description | | --- | --- | --- | --- | | CPU | Backend for Snapdragon™ CPU hardware core(s) | | `QnnCpu` : CPU backend library, same name used across all targets. | | DSP | Backend for Hexagon™ DSP hardware accelerator | | **Note: v## indicates libraries for different hexagon architecture versions are available.**


`libQnnDspV##Skel.so` : DSP native library which is to be loaded using corresponding QnnDspV##Stub
from the device CPU side and is responsible for executing graphs
on the DSP accelerator as a proxy for CPU side backend.


`QnnDspV##Stub` : DSP CPU-side proxy library that communicates with libQnnDspV##Skel.so
on DSP side via RPC channel.


`QnnDsp` : DSP device CPU-side backend library, loads the corresponding DSP stub library based on the SoC.


`libQnnDspV##.so` : DSP native backend library that allows direct integration on DSP without RPC. | | GPU | Backend for Adreno™ GPU hardware accelerator | | `QnnGpu` : GPU backend library, same name used across all targets. | | HTP | Backend for Hexagon™ HTP hardware accelerator | | **Note: v## indicates libraries for different hexagon architecture versions are available.**


`libQnnHtpV##Skel.so` : HTP native library which is to be loaded using corresponding QnnHtpV##Stub
from the device CPU side and is responsible for executing graphs
on the HTP accelerator as a proxy for CPU side backend.


`QnnHtpV##Stub` : HTP CPU-side proxy library that communicates with libQnnHtpV##Skel.so on
the HTP side via RPC channel.


`QnnHtp` : HTP backend library. There are two variants:
(aarch64-android) Android device CPU-side backend library, loads the corresponding HTP stub library based
on the SoC; (x86\_64-linux) x86 Linux host backend serves as an functional simulator for the hardware accelerator and supports graph preparation on x86\_64 hosts.


`libQnnHtpV##.so` : HTP native backend library that allows direct integration on HTP without RPC.


`QnnHtpPrepare` : HTP library which provides functionality to compose and finalize graphs on
the device ARM (CPU) side. This library is automatically loaded by HTP backend library only when one of the following
operations is requested: 1) QnnBackend\_validateOpConfig, 2) QnnGraph\_addNode, 3)
QnnGraph\_finalize, or 4) QnnBackend\_registerOpPackage() with “CPU” target.
If these operations are not requested, this library does not need to be on the device. | | HTA | Backend for Snapdragon™ HTA hardware accelerator | | `QnnHta` : HTA backend library, same name used across all supported targets. | | LPAI | Backend for Snapdragon™ LPAI hardware accelerator | | **Note:**



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| | Saver | Backend which captures QNN API calls and saves them to a file as they are issued by a client.
This can later be replayed for support and troubleshooting. | | `QnnSaver` : Saver backend library. | ## Backend Specific Pages - [DSP](https://docs.qualcomm.com/doc/80-63442-10/topic/dsp_backend.html) - [HTP](https://docs.qualcomm.com/doc/80-63442-10/topic/htp_backend.html) - [HTA](https://docs.qualcomm.com/doc/80-63442-10/topic/hta_backend.html) - [LPAI](https://docs.qualcomm.com/doc/80-63442-10/topic/lpai_backend.html) - [CPU](https://docs.qualcomm.com/doc/80-63442-10/topic/cpu_backend.html) - [GPU](https://docs.qualcomm.com/doc/80-63442-10/topic/gpu_backend.html) - [Saver](https://docs.qualcomm.com/doc/80-63442-10/topic/saver_backend.html) Last Published: Jun 04, 2026 [Previous Topic Windows Setup](https://docs.qualcomm.com/bundle/publicresource/80-63442-10/topics/windows_setup.md) [Next Topic DSP](https://docs.qualcomm.com/bundle/publicresource/80-63442-10/topics/dsp_backend.md)