03livepublic api2026

FlyBrain

An API over the complete male fruit-fly connectome: 211,577 neurons, 11,751 cell types, 124M synapses. Search a neuron, see what feeds it and what it drives, trace a circuit. Built so an AI can literally look something up in a brain.

API docs live stats

[01] what

A brain you can query

A connectome is a wiring diagram: every neuron and every connection between them. This one is the male fruit fly, from the MaleCNS v1.0 release under CC-BY 4.0.

FlyBrain puts it behind a small HTTP API, so you can ask it questions without downloading and wrangling the whole dataset yourself.

[02] numbers

In numbers

neurons: 211,577
cell types: 11,751
synapses: 124M
license: CC-BY

[03] endpoints

What you can ask it

/statscounts for the whole brain
/searchfind neurons and cell types
/type/{cell_type}everything about one type
/type/…/upstreamwhat feeds it
/type/…/downstreamwhat it drives
/circuittrace a path between types

[04] inside

Where the neurons are

optic lobe, intrinsic89,403
central brain, intrinsic32,164
nerve cord, intrinsic13,161
visual projection9,201
nerve cord, sensory6,370
optic lobe, sensory6,098
central brain, sensory4,868
ascending neurons1,846
descending neurons1,314
motor neurons708

Nearly half of the fly's brain is its visual system. The numbers come straight from the API's own /stats.

[05] why

Why build it

Alurx calls it as a tool. So when someone asks how a fly sees, it can look the answer up in an actual brain instead of guessing.

[06] built with

Made with

Python
FastAPI
DuckDB