● Free · Windows · open source

A real fly brain
living on your desktop.

NeuroFly doesn't animate a fly. It runs one. 6,406 neurons and 708,130 synapses, taken from the measured wiring of an actual fruit fly brain, solved a thousand times a second. Lunge at her with your cursor and the same neuron that fires in a real fly fires here — four milliseconds later she is gone.

Download for Windows See how it works No account. No ads. No tracking.
6,406real neurons
708,130real synapses
1,045nerve-cord neurons
1,000/ssimulated timesteps

This is not an animation

Her terrarium sits on the right, her brain on the left — every spike, every firing synapse, live. Nothing she does was scripted.

NeuroFly: the terrarium with the fly, a live brain view, and a measurement console showing firing rates
The workspace: terrarium, connectome view, and a measurement console reading out real firing rates.

Measured wiring, not invented

Every connection comes from FlyWire, the completely mapped wiring diagram of a fly brain. Which cell excites which, and how strongly, is measured — not numbers tuned until the demo looked good.

Each sense hits the right cells

Wind reaches only the wind neurons of her antenna, sound only the hearing cells, heat and cold only her real thermoreceptors. What follows is decided by the wiring, not by a rule someone wrote.

Six legs, actually driven

Walking commands go to a second real network taken from a fly's ventral nerve cord. Joints and ground contact are computed, and the result is reported back to her brain — a closed loop, a hundred and twenty times a second.

A laboratory you can watch

Change the weather, the temperature, the time of day. A spatial map records where she spends her time, and every run exports as a CSV you can analyse yourself.

Things to try in the first five minutes

All of these run through her nervous system. None of them is a canned animation.

Lunge at her with the cursorWatch her looming detectors spike, then the giant fiber — then she is airborne.
Turn the heat upHer real hot cells start firing and the signal travels on into the circuit.
Crank the windThe wind neurons go loud while the escape neuron stays silent — exactly as in a real fly.
Wait for nightfallHer activity follows a real circadian curve, siesta included.
Click a region of the brainStimulate it directly and watch which behaviour comes out.
Record a runTwenty samples a second, every rate and input, straight to CSV.

What NeuroFly is not

This project is only worth anything if its claims hold. So here is what it cannot do.

It is not evidence of feeling

Nobody can read off a simulation whether anything inside it is felt. NeuroFly shows model activity and behaviour — not consciousness, not pain, not emotion. There is deliberately no "sentience meter".

For context the app reports its scope against the eight criteria of Birch et al. (2021) and shows openly which of them appear in the model at all. Most do not: this slice of the brain contains no nociceptors, for instance, so it cannot represent pain even in principle.

Wiring and synapse counts are measured. Cell dynamics, sensory transduction, body mechanics and behaviour are models. That line runs through the whole program and its documentation.

About 6,400 of 140,000 neurons

The extract is her escape and steering core, not a whole brain.

Two animals, one model

Brain and nerve cord come from different specimens, joined by a documented modelled interface — not by real nerve fibres.

Findings get withdrawn

VALIDATION.md logs corrections, including a measurement that overturned an earlier claim this project itself had made.

Download

Free, no account, no advertising. Windows 10 and 11.

Recommended

Windows installer

Installs NeuroFly with a Start-menu entry.

Coming shortly .exe · being packaged

Portable build

Unzip and run. Nothing is installed, nothing is written to your system.

Coming shortly .zip · being packaged

Source code

The full application, all 16 test suites and the data pipeline.

Coming shortly MIT licence

Where the data comes from

Every wiring dataset is public and checkable. The app stores a SHA-256 fingerprint of each input file with every run, so two recordings can never be silently mixed.

SourceWhat it contributesLicence
FlyWire FAFB v783 Brain: 6,338 neurons and 703,381 signed synapse edges, plus real cell types and the thermoreceptors CC BY-NC 4.0
MaleCNS v1.0 Nerve cord: 1,045 neurons for walking, with muscle channels and sensory feedback CC BY 4.0

Because the FlyWire data carries a non-commercial licence, NeuroFly is free and stays free: no ads, no sale, no paid features.

Questions

Is this really a fly's brain?

It is a real, measured piece of one. The connections between these 6,406 neurons were traced in an actual fly brain and are used exactly as measured. What is modelled is how each cell behaves electrically — a standard integrate-and-fire model, not a molecular reconstruction of a neuron.

Does she feel anything?

There is no way to tell that from a simulation, and this program does not claim it. It shows activity and behaviour. That is also why it has no happiness bar, no pain meter and no consciousness score.

Why is it free?

The brain data is published under a non-commercial licence. Selling the program would break that licence, so NeuroFly is free — and it carries no advertising or tracking either.

Will it run on my PC?

Windows 10 or 11 and a few hundred megabytes of disk space. The simulation runs on the CPU, the terrarium on the GPU; a laptop from the last few years is plenty. The app measures its own throughput and lowers render quality before it ever lowers simulation accuracy.

Can I use the code or the data myself?

The code is MIT-licensed — use it, modify it, ship it. The neural data keeps its own licences: FlyWire CC BY-NC 4.0 (non-commercial, attribution) and MaleCNS CC BY 4.0 (attribution).