You can use same tools used for finding them in whole genome sequencing. Be aware that most of your reads are only coming from one strand the majority of the time with RNA-seq, so het/homozygous calls are a lot less reliable.
GATK is kind of the standard, and objectively one of the most accurate when used properly. It's also under continuous development and has tons of options. VarScan2 is also quite good, though it's no longer actively updated. Avoid the samtools/bcftools method that you'll see in a lot of tutorials - it does not do well with low frequency mutations and generally isn't as accurate.
As already mentioned, you can use GATK. But variant calling based on RNAseq data has its tricks, so better follow the best practices of GATK specifically for RNAseq.