GST e-invoicing: GSTN releases list of 5 approved mobile apps for fast verification of GST electronic invoices, easy input tax credit claim. This video is about GST invoice verification. The GSTN has issued new advisory in respect of availability of five official apps for e-invoice verification. Experts say that these apps solve a lot of problems like faster verification of e-invoices which may lead to faster claim of input tax credit and also help in reducing litigations and subdue the problem of fake GST invoices.