System-wide parametric EQ for Windows
Your sound. Every device. Automatically.
A system-wide parametric equalizer for Windows. Tune once per output, and the right sound follows the right device without you touching anything again.
$19 one-time, the day the signed build is ready.
Free software. Build it yourself from source
Everything active is named on the EQ page, so a bump in the graph is never a mystery — you can see what put it there and remove it in one click.
Every setting belongs to the device you tuned it on. Plug in your headphones and their tuning comes back; switch to speakers and theirs does. Mapped to the stable Windows endpoint ID rather than the display name, so it survives renames and re-plugs.
Convolution, then parametric EQ up to 128 bands, then voicing, then driver-type compensation — each written as its own stage in the Equalizer APO config, in that order.
6,028 headphone models and 8,850 responses ship offline from the official AutoEq results. Squiglink is available online as a second source. Once applied, FluidEQ remembers which model your bands came from and says so.
Measures what is actually coming out of your output and flattens what it hears, rather than assuming a target curve and hoping your hardware agrees.
Every layer contributes to a single preamp value derived from the real combined response, so stacking a voicing on a convolution cannot clip you — and removing one gives the headroom back.
Every label, hint, error and tooltip is translated — with a test that fails the build when one falls behind English. The installer offers a language too, preselecting your Windows one.
Local and account-free. No cloud, no telemetry, no proprietary driver, no virtual audio device.
Tap along in the support panel and it reads the real percussion out of whatever you are playing. Thirty-six consecutive perfect taps and the whole interface goes rainbow with the sound.
Equalizer APO comes bundled — nothing is downloaded and there is no second website to visit. Already have it? It is left completely alone.
Choose the device at the top right. Headphones, speakers, a USB DAC, anything Windows lists as an output endpoint.
There is no save step. Every edit attaches itself to the output you are listening on, and comes back when that output does.
No subscription. There is no server to pay for, so there is nothing to bill you for again.
$19 one-time
Not on sale yet. The signed installer and the checkout are both being set up, and an unsigned build is not something worth shipping — so there is nothing to download until the certificate lands. When that will be →
FluidEQ is free software under the GPL. You can always build it yourself from source at no cost. Buying gets you the ready-to-run build, automatic updates, and supports the work.
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. Email support@fluideq.com and say the word "refund" — you do not owe anyone an explanation for not liking a piece of software.
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.