The author created posuto, a package that simplifies parsing Japan Post's notoriously difficult ken_all.csv postal code data. The CSV file contains problematic design choices such as embedded parenthetical notes and line-splitting behavior when fields exceed character limits, making it frustrating for developers.
Background
Japan Post releases ken_all.csv as a public dataset of postal codes, widely used but infamous for its poor design and parsing difficulties in the developer community.
- Source
- Lobsters
- Published
- Aug 29, 2026 at 04:10 PM
- Score
- 5.0 / 10