It seems like my license is not working?

Most of the time, the license stops working due to being out of date. Just contact your sales person and we will offer you a new one.

  • If the license file is restricted to process name, ensure your process is named as it is spelled in the license file.
  • If you are running from Unity player, we would recommend requesting a temporary license for development purposes that also has the process name “Unity”.
  • Make sure that you have not edited the license key file. Renaming it is ok.
  • Are you trying to read the file as text? Please open as binary.
  • Are you trying to access a restricted feature for which you do not have a license?
  • Has your certificate for signing changed? Please request a new license, with your updated certificate information.

When contacting support, it is good if you can provide the error message provided as a response to tobii_device_create_ex()

Connectivity problems

Sometimes connectivity problems can be caused by inadequate power supply to the eye tracker. There can be various reasons for this, either Windows regulates the power, or the USB controller itself does not provide enough. Please see the following support article:

In particular, there is one Asus USB controller that has been causing a lot of issues. It could be worth to double check that you are not using this one:

We also have a couple of USB hubs that we recommend for good power supply

Can I run the Tobii consumer SW on the Eye Tracker 5L or 4L?

Although not officially supported nor tested, yes this currently works. You will need to install both the platform runtime from the PDK of your Eye Tracker 5L (or 4L) as well as the Tobii consumer SW. However, the Tobii Experience App that is part of the Tobii consumer SW stack is a constrained Microsoft store app. This means that it is only possible to download and install if you plug in a supported eye tracker, such as the Tobii Eye Tracker 5.

How does Tobii Eye Tracker firmware upgrade work?

Each release of the Tobii platform runtime includes a specific Eye Tracker firmware version. When the platform runtime makes a connection to a device, it will check the firmware version of that device. If the firmware version differs, the platform runtime will load its specific firmware onto the device.

Can I control what version of drivers and FW that end users of Eye Tracker 4C or Eye Tracker 5 have?

No. Tobii Eye Tracker 5 drivers and SW will update automatically with Windows update and Microsoft Store update. Tobii does not push auto-updates to Tobii Eye Tracker 4C users. However, since the Tobii Eye Tracker 4C is a consumer eye tracker, any end user can go to and download the latest version of the Tobii consumer SW stack.

Tobii Eye Tracker 4L, Tobii Eye Tracker 5L and IS5 DevKit drivers and SW are not published by Tobii for end user to access to update manually.

Can I use Windows Hello with my eye tracker?

Windows Hello is supported for Tobii Eye Tracker 4C, Tobii Eye Tracker 5 and for Tobii Eye Tracker 5L.

How do I deploy Tobii platform runtime service?

Tobii recommends that you create an installer that installs the platform runtime service as well as the rest of your software. When the Tobii platform runtime service is installed as described in the getting started instructions, there is a risk that it gets automatically uninstalled at Windows update.

Can I make an app that works for the Eye Tracker 4C as well as the ET5L?

Yes, as long as you use Tobii Stream Engine.

Can I use the eye tracker with Microsoft Eye Control?

Microsoft Eye Control is only available for eye trackers that have Microsoft HID support. These are typically Assistive Technology eye trackers from Tobii Dynavox.

Can I develop an app for Eye Tracking using UWP?

With the Windows 10 April 2018 update Microsoft has made the Windows.Devices.Input.Preview available for UWP application developers. The API provides the gaze data stream and access to an eye tracker object for the current view without additional software. The API is only supported by eye trackers that have Microsoft HID support, which typically are Assistive Technology eye trackers from Tobii Dynavox. Please check out the Microsoft documentation to learn more

Why is my face green in web camera?

If your web camera does not have an optical filter that removes near infra red (NIR) wavelengths, there is a risk that the NIR light emitted from the eye tracker illuminators may be picked up by your web camera. Typically, if you have a pure RGB camera, this does not happen. However, if your web camera is a Windows Hello camera, it will not have this NIR filter since it will need to capture also the NIR spectrum data.

What is the Tobii Generic Driver?

Tobii Generic Driver is automatically installed by Windows update when the eye tracker is plugged in for the first time. It has two main purposes. For Tobii Eye Tracker 5, it ensures that plug and play works by starting the download and installation of the Tobii consumer SW and drivers. For other eye trackers, it allows platform runtime to access the new eye tracker and load its firmware for the very first time.

How can I set up a peripheral eye tracker with a different angle or position relative to the display?

The rotation and position of the camera is set from factory as part of the geometry mounting data struct (tobii_geometry_mounting_t). This is a hardware configuration that cannot be updated outside of factory. However, this geometry mounting data struct is used when calculating the display area in relation to the eye tracker. To configure the eye tracker for a different position and/or rotation, get the geometry struct through the Tobii Stream Engine API (tobii_get_geometry_mounting), update it locally with a new rotation angle and/or position, then use this to calculate a new display area (tobii_calculate_display_area_basic). Finally, apply this new display area (tobii_set_display_area).

Other apps, or display setups will however not use your locally updated geometry struct if they were to set the display area, so if you run for example the Tobii Configuration app to set up the display, then the display area will not take your rotation into account. To work around this, you can set up a subscription to be notified if any app updates the display area (tobii_notifications_subscribe for TOBII_NOTIFICATION_TYPE_DISPLAY_AREA_CHANGED). And then apply your display plane instead. In practice, setting the display is only done by apps that configure the eye tracker hardware, so usually the risk of collisions between different apps here is low.

How can I make my own calibration?

By using the Stream Engine API calls found in tobii_config.h. A very basic example can be found in the documentation for tobii_calibration_collect_data_2d.

There are many things to consider for how to make a good calibration. If you would like some help on the way, please contact your sales person.

You can also invoke the calibration from Tobii Configuration Application from command line from your own application.

Can I continue using Tobii Pro SDK when scaling from research to product?

Yes, if you are using Eye Tracker 4L. It is however advisable to change the license model from using a per tracker license to an application license. The steps required to switch from per tracker license to application license are stated below.

  1. Go to
  2. Select your target (.NET, Python, etc)
  3. Select the SDK reference guide
  4. Navigate to “examples”
  5. Find the example that shows “Apply licenses” and follow the instructions

If you don’t have your application license, please Contact Tobii

Why would I switch from the Tobii Pro SDK?

If you require support for a platform that is not supported by the Tobii Pro SDK. Please note that Eye Tracker 5L and IS5 Evaluation Kits are not supported by Tobii Pro SDK.  See also the supported platforms & languages for Tobii Pro SDK You may instead find support for that platform through our Tobii Stream Engine API. For more information about available platforms Contact Tobii