Update 10/1/18: Works with transfers now! The bug has been resolved. Happy to recommend this app wholeheartedly now that this major oversight has been fixed.

UPDATE 7/27/18: I've been in contact with the developers via email, and they are saying the issue was caused by a change in Shopify's API - I know that Shopify did change the area of the API they are referring to, and after some discussion, it appears they are on track to release an update soon that will address this change.

I'm a little disappointed they did not proactively adjust their code for this change, and/or test to see if their code would break when the change went into effect, but testing does seem to be something that most of the more feature-rich, but less pricey, apps are lacking. This app DOES have a comprehensive, if not intuitive, UI - which could make it hard to test.

I've updated my review to 4 stars and asked them to let me know when the app is ready for re-testing. I will update again once that is done. If it fails the re-test, I will adjust stars - if it passes, I think 4 stars is appropriate for what is essentially a good app, at a great price, that at the moment lacks some oversight and testing.
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I was very surprised, and disappointed, and a touch angry, to realize this app is not sending email notifications when a transfer accepts inventory. (THANK you other reviewer who pointed this out). We'd been ignorantly relying on this app for a while. I thought it was excellent. I have also emailed the developers to see what they say, but for that reason, unless this is fixed, this app will be an absolute failure for us for sure. I'm greatly aggravated to know this app has been failing to work in that way for a while, and wondering how many sales we've lost as a result.

AMAZING APP. Developer is so helpful!

Simple and effective, saves customers asking when something is in stock, as soon as an out of stock product is added, they get an email and we get another sale.

This is second time I am using this app for my new store. This is very important app all store must have it. This app pay for it self by extra sell which you will get through it. Also their customer care is excellent. My app was setup in less than 12 hours. It works great and had no problem. Thanks for making this app just for $3 while others charges 2 or 5 times more.

- Familyotc.com ( Harry)

Update: Bumped up the stars back to 5!

App is now working great!
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This is a must have app and it comes awesome customer support! App does what it says and the support is great. I requested for the app to be installed and customized according to the look and theme of my shop and voila! Everything was done and running within 1-2 days! Thank you Kundan and Avinash for the support! Keep it up!

Very happy with this app and does what its support to do with good support
they are always been helpful and answered my every request

great app. It has been a big help to www.blackbeltshop.us

app displayed available products out of stock at my store. Support was useless

I really love this app. It's helpful to see which products are in-demand and it brings in a ton of sales. Probably one of the most useful apps we are using on our site.

Amazing App , easy to install and easy to use , the best for my www.seven-50.com website!