  We study the conformal bootstrap for 4-point functions of fermions $\langle
\psi_i \psi_j \psi_k \psi_{\ell} \rangle$ in parity-preserving 3d CFTs, where
$\psi_i$ transforms as a vector under an $O(N)$ global symmetry. We compute
bounds on scaling dimensions and central charges, finding features in our
bounds that appear to coincide with the $O(N)$ symmetric Gross-Neveu-Yukawa
fixed points. Our computations are in perfect agreement with the $1/N$
expansion at large $N$ and allow us to make nontrivial predictions at small
$N$. For values of $N$ for which the Gross-Neveu-Yukawa universality classes
are relevant to condensed-matter systems, we compare our results to previous
analytic and numerical results.
