Questions

As soon as the code-signing certificate and the checkout are both in place. Since 2023 a certificate needs a hardware token or a cloud HSM plus identity verification, which takes weeks rather than days, and that is the part still outstanding.

An unsigned installer is not worth shipping and will not be distributed, so nothing goes on sale until that is done. In the meantime nothing is being held back — the source is public and complete, and you can build the same application yourself for nothing.

Because someone has to build it. FluidEQ's source is public and always will be — if you have Node and half an hour, you can compile your own copy for nothing, and that is a real option, not a trap. What you are buying is the ready-to-run installer, automatic updates, Equalizer APO set up for you, and someone to email when it breaks. That is what funds the next version.

It is the audio engine — a separate open-source project that does the actual filtering at the system level. FluidEQ writes the configuration file it reads. You do need it, and you do not have to go and find it: the FluidEQ installer carries it and offers to run its setup for you.

The build sold here is code-signed, so you get a publisher name rather than "Unknown publisher". SmartScreen may still prompt on early releases: Microsoft removed the automatic reputation that EV certificates used to carry in 2024, so reputation now accrues across downloads instead of arriving with the certificate. Choose More info → Run anyway if you see it.

A copy you compile yourself is not signed and will warn every time. Nothing is wrong with it — signing is one of the things the paid build is paying for.

Anything Windows exposes as an output endpoint, and as many of them as you like. FluidEQ writes one device block per assigned output into its config; Equalizer APO applies the block matching whatever you are listening on. Bluetooth devices work as long as APO is attached to them during its setup — some Bluetooth stacks present the endpoint only while the device is connected, so pair first and then install.

Parametric filtering costs very little; the cost you can measure comes from convolution, and only when you have loaded an impulse response. There is no virtual audio device and no kernel driver in the path. You can also close FluidEQ entirely — the tuning lives in the Equalizer APO config and keeps working with the app shut.

14 days, no questions asked. Two ways, whichever you reach for first: the receipt Paddle emails you links to their portal, where you can find the purchase and ask for the money back — or write to support@fluideq.com and say the word "refund". You do not owe anyone an explanation for not liking a piece of software.

Paddle is the seller of record, so they hold the money and they process the refund; it goes back the way it came. There is no account to sign into here and nothing to cancel — buying was a single purchase, not a subscription.

From the same place as the binary, which is what the GPL requires. The whole repository is at github.com/StartSWest/FluidEQ, and the corresponding source for this exact release is linked in the footer below, alongside the source for the copy of Equalizer APO that the installer bundles.

Buying a build does not restrict what you may do with it afterwards. Use it, study it, change it, give it away — those come with the licence, not with the receipt.