How we reduced our AWS S3 data transfer costs

To satisfy our many cloud services needs, for our matchmaking app, we used AWS platform. We’ve used more than a dozen of their services in the past 2 years and can declare that we are mostly satisfied with them and in most cases we recommend them. However, some services are a bit expensive if you take into account the alternatives, S3 storage is cheap, but data transfer from it, is not.

In our case, we store user provided images, that we serve back to other users. These are images that are constantly changing, generating a considerable amount of data traffic.

With a growing activity and number of users in our app, the data transfer costs started to grow significantly, reaching up to $23/day, making us look for ways to cut down costs.

First we considered using the Cloud Front Service from AWS, but while this would serve our files faster it would not reduce the cost (actually increase it a bit).

We optimised the images as much as we could without loosing visible quality:
- saved them as jpeg and not png;
- we lowerd the maxium resolution of the images;
- we increased a bit the compression level.
After these steps the data transfer cost went down with about 15–20%. It wasn’t enough.