In the first part of this project, we will see what is a PPP, how it works, and a comparison between them and other Positioning methods. First of all, we are going to see how many GNSS constellations are there, and how they work a constellation. We will see the type of working witch we can classify all the positioning methods, to end in the PPP method. We will explain the PPP method in more detail. We will start with how it was created, how it is nowadays, and where it could become in the future. We will also see the functioning with the ionospheric model and how to correct its errors. To final this section, we will see how we collect the data to work with this method, in our case, we will talk about GFZ and IGS. The second part of the project, is about a comparison between several PPP online service and some PPP programs. For that we are going to take several IGS Stations at the same day, and we will use different online service and programs to do de solution. We will show the programs and the service that we work with and some of them that we don't work with it. We are going to see also the information that we need to do the calculation in a detail, and how to download it. Finally, we will check the results of the different PPP programs and online service to see what is better, and the benefits of each one. For the comparison we will use several graphs and tables, to make easy the visualization of the results. We will check also, if the time lapses of the measurements, affect to the results, and if the utilization of a multiconstalation, helps to have a better result. In the conclusions we will check that NRCAN, is the best PPP online service, and gLAB, is the best PPP program. However, it is RTKLIB the program that you can change more, in other words, is the program that you have more control about them, you can change the constellation that you are working, the SBAS, the ionospheric correction... In the other 2 comparisons, we have reached the conclusion, that working with more data, is better, so if we take more time lapses, the results, is more accurate. Working with a multiconstellation is it worth it, for the same reason that the time lapses, since in the multiconstellation, you have more satellites for work with it.