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Figure 1 shows the technical architecture for an open loop payment and its interaction with Google Wallet:
Figure 1. Data flow between Google Wallet, the TSP, and the transit agency.
The following are definitions for each part of the technical architecture.
Mobile Device with Google Wallet
Mobile devices powered by Android OS allow users to securely add their cards to Google Wallet. Google Wallet facilitates the process of tokenization, which is when payment networks tokenize the card and add a device-specific token on the mobile device. For more information about tokenization, see How payments work.
Google Wallet is compatible with the majority of modern Android devices across multiple manufacturers and form factors. For minimum requirements, see Prerequisites.
Transit Reader
Transit readers are typically card readers at a transit station or bus entry point. The transit readers and terminals receive a payment credential from Google Wallet in the same way that they receive a payment credential from a physical, contactless credit or debit card. To accept contactless payments, the transit reader must be compliant with EMV protocol. For more information, see Basic functionality requirements.
In order for the readers to become compliant and support mobile EMV payments, they might need software upgrades. For more information about the Google requirements for EMV tags, see Basic functionality requirements.
For readers that are offline or without a reliable high-speed internet connection, the transit operations are required to enable offline device authentication (ODA). For minimum requirements, see Prerequisites.
Transit Server
The backend server. Transit operators or their systems integrators typically operate it. Card readers often connect to the server on an intermittent basis and batch transactions together. Servers receive batch processing requests and pass requests on to the transit operator’s payment processor.
Payment Processor
The payment processor is the firm that handles transactions. It de-tokenizes the tokenized payment credentials and completes the transaction with the issuing bank. For more information about payment processing, see How payments work.
Token Service Provider (TSP)
The TSP for payment networks provides services to tokenize and de-tokenize credit and debit cards. Processors leverage TSPs to retrieve payment credentials based on the tokens the Google Wallet app sends to them.
Google Server
The server provides a link between Google's partners and the user's Android-powered mobile device. The TSP sends transaction notifications, such as authorization and settlement notifications, to the Google servers. The Google servers use this information to show notifications and transaction receipts to the user.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-03-06 UTC."],[[["\u003cp\u003eGoogle Wallet enables contactless payments on Android devices for transit systems by tokenizing payment card information for secure transactions.\u003c/p\u003e\n"],["\u003cp\u003eTransit readers need to be EMV compliant and potentially upgraded to accept contactless payments from Google Wallet similar to physical contactless cards.\u003c/p\u003e\n"],["\u003cp\u003eTransactions flow from the mobile device to the transit reader, then to the transit server and payment processor which de-tokenizes the payment information to complete the purchase.\u003c/p\u003e\n"],["\u003cp\u003eThe TSP works with payment networks to manage tokenization and de-tokenization, while Google servers handle transaction notifications and user receipts.\u003c/p\u003e\n"],["\u003cp\u003eOffline device authentication (ODA) is required for transit readers with limited or no internet connectivity to support mobile EMV payments.\u003c/p\u003e\n"]]],["Google Wallet allows Android users to add and tokenize payment cards on their devices. Transit readers, compliant with EMV protocol, receive payment credentials from Google Wallet. Transit servers manage batch transactions from readers, relaying them to the payment processor. The payment processor de-tokenizes credentials and finalizes transactions. The Token Service Provider (TSP) facilitates card tokenization and de-tokenization. Google servers link partners with user devices, handling transaction notifications.\n"],null,["Figure 1 shows the technical architecture for an open loop payment and its interaction with\nGoogle Wallet:\n**Figure 1.** Data flow between Google Wallet, the TSP, and the transit agency.\n\nThe following are definitions for each part of the technical architecture.\n\nMobile Device with Google Wallet\n\n: Mobile devices powered by Android OS allow users to securely add their cards to\n Google Wallet. Google Wallet facilitates the process of tokenization, which is when\n payment networks tokenize the card and add a device-specific token on the mobile device. For\n more information about tokenization, see\n [How payments work](https://support.google.com/androidpay/merchant/answer/6345242).\n\n Google Wallet is compatible with the majority of modern Android devices across multiple\n manufacturers and form factors. For minimum requirements, see\n [Prerequisites](/wallet/tickets/open-loop/get-started/prerequisites).\n\nTransit Reader\n\n: Transit readers are typically card readers at a transit station or bus entry point. The\n transit readers and terminals receive a payment credential from Google Wallet in the same\n way that they receive a payment credential from a physical, contactless credit or debit card. To\n accept contactless payments, the transit reader must be compliant with EMV protocol. For more\n information, see\n [Basic functionality requirements](/wallet/tickets/open-loop/technical-integration/basic-requirements).\n\n In order for the readers to become compliant and support mobile EMV payments, they might\n need software upgrades. For more information about the Google requirements for EMV tags, see\n [Basic functionality requirements](/wallet/tickets/open-loop/technical-integration/basic-requirements).\n\n For readers that are offline or without a reliable high-speed internet connection, the\n transit operations are required to enable\n [offline device authentication](/wallet/tickets/open-loop/technical-integration/basic-requirements#oda) (ODA). For minimum requirements, see\n [Prerequisites](/wallet/tickets/open-loop/get-started/prerequisites).\n\nTransit Server\n: The backend server. Transit operators or their systems integrators typically operate it. Card\n readers often connect to the server on an intermittent basis and batch transactions together.\n Servers receive batch processing requests and pass requests on to the transit operator's payment\n processor.\n\nPayment Processor\n: The payment processor is the firm that handles transactions. It de-tokenizes the tokenized\n payment credentials and completes the transaction with the issuing bank. For more information\n about payment processing, see\n [How payments work](https://support.google.com/androidpay/merchant/answer/6345242).\n\nToken Service Provider (TSP)\n: The TSP for payment networks provides services to tokenize and de-tokenize credit and debit\n cards. Processors leverage TSPs to retrieve payment credentials based on the tokens the\n Google Wallet app sends to them.\n\nGoogle Server\n: The server provides a link between Google's partners and the user's Android-powered mobile\n device. The TSP sends transaction notifications, such as authorization and settlement\n notifications, to the Google servers. The Google servers use this information to show\n notifications and transaction receipts to the user."]]
