It's active, I had the same worries about a week or two back because this particular vendor ran out of the sodium salt. It's definitely weaker, though it is also longer lasting and has pretty much no taste... seriously, I can dump my whole dose on my tounge and all I taste something akin to flower. The sodium salt on the other hand is truly vile tasting stuff.
When I do take the sodium salt I usually dose about 300-350mgs, with the free acid I required around 450mgs. You may find the conversion rate different as this is just a rough effect comparison from one person so take it fwiw. Drawing comparisons becomes difficult when you factor in tolerance and individual variation.
Never been much of a fan of tianeptine but despite the weaker potency I honestly think I prefer the free acid. The duration becomes closer to something like oxy rather down of the steep up and down of the sodium salt, one of my biggest turn offs previously. The stuff is dirt cheap dose for dose regardless of the form so I can stand to lose some potency