I found lot of one shot drum samples, but I need for free synth, stab, instrument one shots.
cymatics have loads up for free, and there's these shits called soundfonts too, google that, they tend to be orchestral but you can find anything.
There is a free sampler VST plugin for desktop called Zampler RX. It loads synth sounds in .sfz soundfont format. You can download a lot of good multisampled sound libraries for free.
The Caustic PCM-Synth can't load .sfz soundfont but can load .sf2 soundfonts. If you download those .sfz soundlibraries you can use the multisamples from those patches.. Just make sure you rename them with an underscore in the filename: junosaw_C3, junosaw_D#3. After making sure the files have the correct filenames, zip the files and load that zip file in the PCM Synth. Because of the note in the filenames the samples are auto mapped! Coolll!