Coding for Resilience: When Free Geocoding APIs Leave Gaps

Relying on a single free API can silently break production features—in this case, turning nearby gas stations into 8,000-mile distances when a popular geocoding service returns 404s for valid ZIP codes. This story demonstrates why production systems need layered resilience: combining static reference data, caching, and multiple APIs ordered by cost and reliability, not just picking the cheapest source and hoping it works.