When we started working on BTC Map, we inherited about 8,000 places which were last verified before 2015, so we quickly figured out that adding merchants to the map is not enough, it’s also important to make sure that our data is reliable.

Unfortunately, OpenStreetMap doesn’t make it easy to figure out if the data is still reliable, at least, not out of the box. There are a few optional tags which can be used to keep track of the timestamps, such as check_date and survey:date, but most Bitcoin merchant locations didn’t have those tags, so I had to figure out the dates of the most recent full verifications and add them manually. It took me a few weeks, but now we have a full timestamp coverage, which allows us to measure the age of our data. It currently stands at ~460 days, and I hope we’ll be able to bring it down to 365 days or even lower.