There is data for every transitive subgroup of $S_n$, up to conjugation, for $n\leq 47$ and $n\neq 32$. For transitive subgroups of $S_{32}$, there is data for all groups $G$ where either $|G|<512$ or $|G|> 40{,}000{,}000{,}000$, plus some other groups of intermediate sizes when they appear elsewhere in the LMFDB.
For most groups, sibling and resolvent information is given for subgroups of index $\leq 47$. In some cases, this information was only computed with smaller bounds, and the individual group pages so indicate. If sibling information for a subgroup of $S_n$ was only computed to a bound less than $n$, then there is no information on arithmetic equivalence.