A single button to record a new shave, 2 taps to record a new blade.
A handy color grading that lets you see at a glance when things might go dull (the graduation can be configured)
Completely free, with no adverts, no in-app purches, no internet connectivity, no tracking.
The app is provided in the hope it will be helpful to you and nothing else.
Knowing when to change the blade in a DE razor is something that you have to learn. It tends to take about a week of daily use before a used blade starts tugging at hairs rather than slicing through them. Of course the duration of a blade depends on a lot of factors, such as how stubbly you are and the make of blades, but 5 uses seems to be about average.
At the point the blade starts to dull, one tends to instinctively press a fraction harder. This extra pressure ends up causing nicks and razor burn. By keeping track of the number of times you've used the blade, you get to know when you need to switch it out. Or at least it makes you think about those things.
As well as the main spreadsheet-like application there is also a widget that shows the usage and the date from the last time you recorded a shave using the app.
The software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.