Testing location data with edge cases, not just happy paths
An address in a well mapped city center tells you almost nothing about how your system handles a rural route, a disputed border, or a query near the poles. Test the hard cases deliberately.
Data licensing and why some sources can't be used commercially
It is a common and understandable mistake to assume that if a dataset is publicly accessible, it is automatically fine to use inside a commercial product. In practice, public accessibility and commercial usability are two entirely separate questions, and a meaningful amount of location data that is genuinely free to view, download, or reference for personal or research purposes carries licensing terms that specifically prohibit or restrict its use inside a product you charge money for, or even inside a free product that is part of a broader commercial business.
This distinction matters because location datasets are compiled through real, often substantial ongoing effort: surveying, aggregation, verification, and continuous maintenance to keep the data current as the real world changes underneath it. The organizations and governments that produce this data reasonably attach licensing terms that reflect how they want that effort used and, in many cases, compensated, and those terms vary enormously from one source to the next. Some data is released under genuinely open terms with generous or no commercial restrictions. Some is free for personal or non-commercial use only. Some requires a specific paid commercial license before any business use is permitted, regardless of how the underlying data is technically accessed or how small the intended use might seem.
Building a product on any external location data source without checking this specifically, and without keeping track of it over time, since terms can and do change when they are updated or reissued, is a genuine business and legal risk, not merely a technical or data quality concern in the sense most of this series has otherwise focused on. It is worth treating licensing due diligence as its own explicit step in evaluating any data source, separate from and in addition to evaluating that source's actual accuracy and coverage, since a dataset can be excellent on every technical measure and still be the wrong choice if its licensing terms do not actually permit the specific commercial use you have in mind.
This is also, practically speaking, part of why commercial geocoding and location APIs exist at all as a category of product, rather than every company simply compiling and using open data directly on their own. A significant part of what you are paying for with a commercial provider is the licensing clarity itself: a clear, contractual right to use the resulting data commercially, with the underlying licensing complexity, and its ongoing maintenance as terms shift over time, handled on your behalf rather than left for you to track and manage yourself across every individual source involved.
If you are evaluating any provider for a commercial product, ask directly and explicitly about licensing terms for commercial use, not just about accuracy or coverage figures, since a technically excellent dataset with the wrong license is not actually usable for your purpose regardless of how good the data itself looks in isolation. Our pricing page covers usage terms for both the free daily allowance and paid usage beyond it.