Pirateship fully integrates with Etsy and posts your tracking numbers automatically just like Etsy Labels does. It is free, except for what you pay for the postage. There are no monthly fees like some discount postage services.
First and foremost, I use Pirateship because I can get help from a real human who has the power to act when I have a problem in under a minute or two. On Etsy you are lucky if they ever answer you at all, and when they do it is days later.
There are rarely glitches on Pirateship like there are on Etsy Labels, and on the rare occasion when one occurs, they fix it immediately, not days later like Etsy does.
Pirateship also offers UPS at up to a 70% discount, and that is often cheaper than USPS's Ground Advantage, especially on larger packages.
International rates are much cheaper than Etsy if you open a chat and ask for the Simple Export Rate to be activated. You only have to ask once and then it is there after that.
On Etsy Labels, Acendia packages are only tracked until they leave the US, then it shows nothing until the package is actually delivered. On Etsy Labels, foreign packages often get lost or delayed, and without being able to tell your customer where the package is in it's journey breeds distrust, and they often think you ran off with their money and demand a refund before the package gets there but after you have mailed it.
Pirateship says they bought the delux Ascendia plan, while Etsy bought the Regular plan.
On Pirateship, packages show every hop along the way, even after they leave the US, and there are rarely delays unless they are caused by Customs clearance. I find just being able to tell customers where their package is calms them down and I get less demands for refunds, and there are less delays in general.
If you still don't trust Ascendia, on Pirateship you can still ship foreign orders without using them, although the cost is higher.
