Dear colleague,

PsychToolbox (PTB) was first released 30 years ago this year and remains one of the most widely used software packages for running behavioural experiments. It offers unrivalled cross-platform visual and audio fidelity and components of PTB underlie functionality in critical parts of other toolboxes, such as PsychoPy.

PTB has allowed many of us to establish our careers in science, it is used in countless labs around the world, in industry, our teaching, and student supervision and training. It is core in too many scientific publications to count and has been cited over 40000 times.

New for 2025 is native support for Apple Silicon and importantly a new funding model. This will involve a licence to use PsychToolbox, but importantly PsychToolbox will remain open source.

If you want to see PsychToolbox continue into the future, please support us by buying a software licence for your lab at www.psychtoolbox.net. Buy now and receive a license at a low early-bird rate.

Please read on for more details regarding why action is needed now.

Why a new funding model? Despite repeated years of effort, the uptake of the donation model and the paid support services model for funding PTB has not provided anywhere near sufficient income to support the full-time development of PTB. You might not realise this, but maintaining PTB is the lead developer’s full-time job. The current financial situation is unsustainable, which means that PTB is at the point where development and maintenance may cease in a matter of months.

How does the new funding model work? Going forward, future versions of PTB for Windows and macOS will require a yearly (very reasonably priced) software license. PTB will remain open source, but development will cease if this funding route is unsuccessful. Full details of how licensing works can be found at the following link. Any proceeds will go directly to funding the salary of PTB’s main and full-time developer, Mario Kleiner. For a limited time only, we are offering a discounted early-bird rate for the new software licences, see our commercial website for full details: www.psychtoolbox.net. Please post any questions you may have to the psychtoolbox forum at https://psychtoolbox.discourse.group/.

What the new funding is not The new funding model is not an attempt to paywall PTB. The project remains open source. PTB will also remain free on Linux for the time being, ensuring that labs with limited funding can use PTB on the free Linux operating system. The money raised through licenses will directly fund the continued development and existence of PTB. See the following link for further details.

As we enter the 30th year for PTB, if you want to see PTB exist into the future, please act now and buy a software licence for your lab at www.psychtoolbox.net. Over the next few months, if this last option for putting PTB on a sustainable financial footing fails, PTB as it is now will be unviable going forward.

Mario Kleiner and the Psychtoolbox Team