Mobile device payments

1. A computer-implemented method comprising:

receiving, at one or more computing devices of a payment service and in association with a transaction between a customer and a merchant, a message from a computing device of the customer, wherein the message includes data obtained via an optical scan of a code by the computing device of the customer, wherein the code is displayed at a point-of-sale of the merchant or a website of the merchant;

receiving, by the one or more computing devices of the payment service and from an application executing on a computing device of the merchant, a request to authorize payment for the transaction;

identifying, by the one or more computing devices of the payment service, a customer account of the customer and a merchant account of the merchant based on the message received from the computing device of the customer;

accessing, by the one or more computing devices of the payment service, and based on identifying the customer account of the customer, payment data previously associated with the customer account;

authorizing, by the one or more computing devices of the payment service, the payment using the payment data previously associated with the customer account; and

providing, by the one or more computing devices of the payment service, notification of the authorization of the payment to the application executing on the computing device of the merchant or an application executing on the computing device of the customer.

2. The computer-implemented method as claim 1 recites, wherein the data comprises a merchant identifier.

3. The computer-implemented method as claim 1 recites, wherein the merchant account comprises financial account information associated with the merchant.

4. The computer-implemented method as claim 1 recites, wherein the one or more computing devices of the payment service process the payment without (i) the payment data being read from a payment instrument at a time of the transaction or (ii) the payment data being input by the customer at the time of the transaction.

5. The computer-implemented method as claim 1 recites, wherein the message includes an amount of the payment.

6. The computer-implemented method as claim 1 recites, wherein the request to authorize the payment includes an indication that the merchant has verified an identity of the customer.

7. The computer-implemented method as claim 1 recites, wherein the message comprises a first message, and the method further comprising:

sending, by the one or more computing devices of the payment service, a request for approval of the payment to the computing device of the customer; and

receiving, by the one or more computing devices of the payment service, a second message from the computing device of the customer approving the payment,

wherein authorizing the payment is based at least in part on receiving the second message.

8. The computer-implemented method as claim 7 recites, further comprising:

determining, by the one or more computing devices of the payment service, that the request for approval and the second message were received within a threshold period of time of each other,

wherein authorizing the payment is further based at least in part on the determining that request for approval and the second message were received within a threshold period of time of each other.

9. A system comprising:

one or more processors;

one or more non-transitory computer-readable media storing computer-executable instructions that, when executed, cause the one or more processors to perform operations comprising:

receiving, at one or more computing devices of a payment service and in association with a transaction between a customer and a merchant, a message from a computing device of the customer, wherein the message includes data obtained via an optical scan of a code by the computing device of the customer, wherein the code is displayed at a point-of-sale of the merchant or a website of the merchant;

receiving, by the one or more computing devices of the payment service and from an application executing on a computing device of the merchant, a request to authorize payment for the transaction;

identifying, by the one or more computing devices of the payment service, a customer account of the customer and a merchant account of the merchant based on the message received from the computing device of the customer;

accessing, by the one or more computing devices of the payment service, and based on identifying the customer account of the customer, payment data previously associated with the customer account;

authorizing, by the one or more computing devices of the payment service, the payment using the payment data previously associated with the customer account; and

providing, by the one or more computing devices of the payment service, notification of the authorization of the payment to the application executing on the computing device of the merchant or an application executing on the computing device of the customer.

10. The system as claim 9 recites, wherein the transaction is conducted via the website of the merchant.

11. The system as claim 10 recites, wherein the one or more computing devices of the payment service cause display of the code on the website of the merchant.

12. The system as claim 9 recites, wherein the transaction is conducted at the point-of-sale of the merchant.

13. The system as claim 12 recites, wherein the payment service causes display of the code on a point-of-sale device at the point-of-sale of the merchant.

14. The system as claim 9 recites, wherein the message comprises a first message, and the operations further comprising:

sending, by the one or more computing devices of the payment service, a request for approval of the payment to the computing device of the customer;

receiving, by the one or more computing devices of the payment service, a second message from the computing device of the customer approving the payment; and

determining, by the one or more computing devices of the payment service, that the request for approval and the second message were received within a threshold period of time of each other,

wherein authorizing the payment is based at least in part on the determining that the request for approval and the second message were received within a threshold period of time of each other.

15. The system as claim 9 recites, further comprising:

sending, by the one or more computing devices of the payment service and to the computing device of the merchant, an indication of receipt of the message from the computing device of the customer,

wherein receiving the request to authorize the payment is at least partly responsive to sending the indication of the receipt.

16. The system as claim 9 recites, wherein receiving the message from the computing device of the customer is at least partly responsive to receiving, by the one or more computing devices of the payment service and from the computing device of the merchant, the request to authorize the payment.

17. One or more non-transitory computer-readable media storing computer-executable instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:

receiving, at one or more computing devices of a payment service and in association with a transaction between a customer and a merchant, a message from a computing device of the customer, wherein the message includes data obtained via an optical scan of a code by the computing device of the customer, wherein the code is displayed at a point-of-sale of the merchant or a website of the merchant;

receiving, by the one or more computing devices of the payment service and from an application executing on a computing device of the merchant, a request to authorize payment for the transaction;

identifying, by the one or more computing devices of the payment service, a customer account of the customer and a merchant account of the merchant based on the message received from the computing device of the customer;

accessing, by the one or more computing devices of the payment service, and based on identifying the customer account of the customer, payment data previously associated with the customer account;

authorizing, by the one or more computing devices of the payment service, the payment using the payment data previously associated with the customer account; and

providing, by the one or more computing devices of the payment service, notification of the authorization of the payment to the application executing on the computing device of the merchant or an application executing on the computing device of the customer.

18. The one or more non-transitory computer-readable media as claim 17 recites, wherein the message comprises a first message, and the operations further comprising:

sending, by the one or more computing devices of the payment service, a request for approval of the payment to the computing device of the customer; and

receiving, by the one or more computing devices of the payment service, a second message from the computing device of the customer approving the payment,

wherein authorizing the payment is based at least in part on receiving the second message.

19. The one or more non-transitory computer-readable media as claim 18 recites, further comprising:

determining, by the one or more computing devices of the payment service, that the request for approval and the second message were received within a threshold period of time of each other,

wherein authorizing the payment is based at least in part on the determining that request for approval and the second message were received within a threshold period of time of each other.

20. The one or more non-transitory computer-readable media as claim 17 recites, wherein identifying the customer account based on the message comprises identifying the customer account based at least in part on a customer identifier associated with the application executing on the computing device of the customer.