Overall, we did two testing rounds during the development of Kotikatu365. During the first round, we only tested with an Invision prototype that was made of static images. We found out that younger testers didn’t have that many issues, but senior users had problems especially with registration.
The registration had been designed using good usability principles like keeping the contrast optimal, avoiding using small fonts and keeping the steps as simple as possible, but with end user testing, we noticed that the design had to be even clearer for the senior users.
We solved the discovered problems by making the fonts bigger, adding more whitespace and making the inputs stand out better. After this, we did some internal testing to verify the changes and only after that started coding the service.