  We present the design, realization and performance of a three-axis vector
nano Superconducting QUantum Interference Device (nanoSQUID). It consists of
three mutually orthogonal SQUID nanoloops that allow distinguishing the three
components of the vector magnetic moment of individual nanoparticles placed at
a specific position. The device is based on Nb/HfTi/Nb Josephson junctions and
exhibits linewidths of $\sim 250$ nm and inner loop areas of $600 \times 90$
nm$^2$ and $500 \times 500$ nm$^2$. Operation at temperature $T=4.2$ K, under
external magnetic fields up to $\sim 50$ mT is demonstrated. The experimental
flux noise below $\sim 250$ ${\rm n}\Phi_0/\sqrt{\rm Hz}$ in the white noise
limit and the reduced dimensions lead to a total calculated spin sensitivity of
$\sim 630$ $\mu_{\rm B}/\sqrt{\rm Hz}$ and $\sim 70$ $\mu_{\rm B}/\sqrt{\rm
Hz}$ for the in-plane and out-of-plane components of the vector magnetic
moment, respectively. The potential of the device for studying tridimensional
properties of individual nanomagnets is discussed.
