In general: use TLS. Only if the data stays within a limited network that is not accessible from the outside, you might possibly get away to do it without TLS.

There are a number of options for creating an encrypted tunnel, among which IPSec and OpenVPN. Although possible, all administrators will first frown upon your lack of TLS support and then curse you for requiring them to build the tunnel. All require additional software, and all are harder to configure than simply using TLS. Some may need additional hardware to run reliably.

The only valid reason for not doing TLS is that you have very high (not just high, VERY high) transaction volumes. In that case, you would adapt your network architecture to accommodate for that quantity of transactions. If that is a possible deployment, you could provide an option to switch it off. But default should be TLS.

In general: use TLS. Only if the data stays within a limited network that is not accessible from the outside, you might possibly get away to do it without TLS.

There are a number of options for creating an encrypted tunnel, among which IPSec and OpenVPN. Although possible, all administrators will first frown upon your lack of TLS support and then curse you for requiring them to build the tunnel. All require additional software, and all are harder to configure than simply using TLS. Some may need additional hardware to run reliably.

The only valid reason for not doing TLS is that you have very high (not just high, VERY high) transaction volumes. In that case, you would adapt your network architecture to accommodate for that quantity of transactions. If that is a possible deployment, you could provide an option to switch it off. But default should be TLS.

In the past, TLS (or SSL at that time) may not not have been common. It is now.

In general: use TLS. Only if the data stays within a limited network that is not accessible from the outside, you might possibly get away to do it without TLS.

There are a number of options for creating an encrypted tunnel, among which IPSec and OpenVPN. Although possible, all administrators will first frown upon your lack of TLS support and then curse you for requiring them to build the tunnel. All require additional software, and all are harder to configure than simply using TLS.

The only valid reason for not doing TLS is that you have very high (not just high, VERY high) transaction volumes. In that case, you would adapt your network architecture to accommodate for that quantity of transactions. If that is a possible deployment, you could provide an option to switch it off. But default should be TLS.

In general: use TLS. Only if the data stays within a limited network that is not accessible from the outside, you might possibly get away to do it without TLS.

There are a number of options for creating an encrypted tunnel, among which IPSec and OpenVPN. Although possible, all administrators will first frown upon your lack of TLS support and then curse you for requiring them to build the tunnel. All require additional software, and all are harder to configure than simply using TLS. Some may need additional hardware to run reliably.

The only valid reason for not doing TLS is that you have very high (not just high, VERY high) transaction volumes. In that case, you would adapt your network architecture to accommodate for that quantity of transactions. If that is a possible deployment, you could provide an option to switch it off. But default should be TLS.