First, some background information: Tahor is an application connecting women with rabbanim to answer questions on bedika cloths. The application uses various techniques to ensure proper color and size calibration.
The app developers state clearly that the app is only meant to be used for "women who either cannot, or do not, ask their Taharat Hamishpacha questions to a Rav."
We at Tahor completely encourage all women to bring their bedikas to
their Rav. However, we recognize the fact that many women do not do
this. It is for these women that Tahor app was created. Our goal at
Tahor is to make sure all these women can be included in this mitzvah.
Their rabbinic authorities are
- R K. Auman, the former president of the Rabbinical Council of America and the Dean of the Yoatzot Halacha Program in the United States
- R E. Davis, a YU graduate and the Morah D’asrah at the Young Israel of Hollywood, FL
- R Ariel Edry, a Talmudic University graduate who serves as a rav
- R D Bixon, a YU graduate and the Rav of Beth Israel in Miami Beach
The app has generated some opposition: for instance, from R Sholom Ber Shuchat, a Chabad Rabbi and Dayan from Agudas Harabonim of the US and Canada, who came out against its use. (See here and there for Tahor's response, and here for additional opposition from Chabad rabbis).
Ultimately every woman should ask her own rabbi if he supports the use of this app for cases where she cannot direct her questions directly to him.