A computer-implemented method for securely receiving data via a third-party webpage, comprising: generating, with a payment web server, configuration data in response to a request from a merchant web server, the configuration data comprising a public key of a first key pair; digitally signing, with the payment web server, the configuration data based on a private key of a second key pair; transmitting, by the payment web server, the digitally signed configuration data to the merchant web server; in response to the merchant web server receiving the configuration data from the payment web server, transmitting, by the merchant web server, data comprising the configuration data to a user device, wherein the data is configured to cause the user device to render a webpage through a web browser application executed by the user device, the webpage including a master frame and at least one other frame (303a, 303b), wherein the frames (303a-303c) load content from a domain that is independent from a domain that hosts the webpage; verifying, with the user device, the digitally signed configuration data based on a public key of the second key pair; rendering, by a browser executed by the user device, the webpage; establishing communication between the master frame and the one other frame (303a, 303b) in response to rendering the master frame and/or verifying the digitally signed configuration data, wherein the digitally signed configuration data restricts communication of the master frame to the at least one other frame (303a, 303b) and the merchant webpage; aggregating, by the master frame, data input by a user from each frame (303a-303c); encrypting, by the master frame, the data input by the user using the public key of the first key pair to generate encrypted data; and receiving, from the master frame at the payment web server, the encrypted data. generating, with a payment web server, configuration data in response to a request from a merchant web server, the configuration data comprising a public key of a first key pair; digitally signing, with the payment web server, the configuration data based on a private key of a second key pair; transmitting, by the payment web server, the digitally signed configuration data to the merchant web server; in response to the merchant web server receiving the configuration data from the payment web server, transmitting, by the merchant web server, data comprising the configuration data to a user device, wherein the data is configured to cause the user device to render a webpage through a web browser application executed by the user device, the webpage including a master frame and at least one other frame (303a, 303b), wherein the frames (303a-303c) load content from a domain that is independent from a domain that hosts the webpage; verifying, with the user device, the digitally signed configuration data based on a public key of the second key pair; rendering, by a browser executed by the user device, the webpage; establishing communication between the master frame and the one other frame (303a, 303b) in response to rendering the master frame and/or verifying the digitally signed configuration data, wherein the digitally signed configuration data restricts communication of the master frame to the at least one other frame (303a, 303b) and the merchant webpage; aggregating, by the master frame, data input by a user from each frame (303a-303c); encrypting, by the master frame, the data input by the user using the public key of the first key pair to generate encrypted data; and receiving, from the master frame at the payment web server, the encrypted data.