I have been asked so often that I’m putting the answer here just in case you need to know as well...
Pickling salt is a pure salt. It doesn’t contain any additives like the anti-caking agents or iodine. The result is a clear brine and clean flavour. The additives can cause cloudy brine that leaves you questioning whether your jars are safe to eat (bacteria or salt choice?) or can affect the colour and flavour of you finished jars.
You can switch to an alternate PURE salt, but keep in mind that different salts are different shapes and therefore measure differently. Kosher salt, for example, can come in at only half the salt in the same measuring cup. The salt is key to your safe preserving so find out what the equivalency is in your salt choice before you start.
And no, I don’t have any pickling salt in stock. My supplier is out too.