If you are looking for free PSN codes then try looking for them online from websites that you can trust for the same. There are different ways that these websites that offer free PSN codes are able to do that because they tend to have partnerships with the network that can be of a different nature.
For example, if you purchase a gaming device that supports the PlayStation gaming system, the retailer might as well offer you some free PSN codes that go along with it. Therefore in order to qualify for free PSN codes through such partnerships, you will have to make a purchase from a retailer that participates in this scheme.
Others also can provide you with free PSN codes however they might ask you to complete some tasks in return for these codes. And these tasks could vary depending upon the website that may be offering them.
Some websites may ask you to complete a survey or two which do not take you more than a few minutes to complete and upon successful completion they might offer you with free PSN codes.
And other websites that offer a psn code may ask you to download a new software program that may have been developed by one of their partnerships so you can test it and provide them with your feedback.
Once you have successfully completed this task they would be willing to offer you free PSN codes. But you will always have to be cautious when proceeding with such websites because some of them may get you to complete a number of tasks without providing you with free PSN codes as promised at the end of the task.