I have used it in the past.
At the wrong concentration it will screw your seedlings over for life. It can inhibit germination as well, and deregulate other processes.
I got a couple dwarfisms induced, or went from 40% germination to a 100% forever dormancy.
If you're going to work with this stuff, make sure you store it well, know how to dissolve it, and for sure know how to do math with moles, liters, milliliters, micrograms, milligrams and related conversions.
Not all plant hormones are safe for humans either. So make sure you read the documentation amd google around a little.
For germination, if you feel the need for GA3, maybe check your seed source or technique instead.. I've found over the years that this is way more effective. Some seeds don't germinate because they're dead. GA3 isn't going to help in those cases. Also the concentration in literature is often based on a certain "lab strain" of a plant, so it might not translate to wildtype.
Store lye and acids in bottles, inside a plastic tub-container at least the same volume as the bottles and never together. I've seen highly educated people pour liquid nitrogen down the drains, and then throwing in highly concentrated acid.. making a caustic bomb for everyone in the room.. I'm not saying anyone here is stupid, but please be careful! Some hormones require HCl or KOH solutions to be dissolved, and those are easy to make in excess.