Analyzing 40 Years of Japanese Public Open Data in 3 Minutes with DuckDB (No API Keys, In-Memory Parquet)
The Hidden Goldmine (and Nightmare) of Japan's Open Data Japan’s government ministries publish massive amounts of open public data: Multi-billion-dollar national procurement contracts (Digital Agency / GEPS) 44-year historical nationwide land valuation benchmarks (MLIT) Over 5 million corporate registry records (National Tax Agency) 470,000+ registered medical and eldercare facilities (MHLW) For…
Japan's government ministries release extensive open public data, including multi-billion-dollar contracts, land valuation records, corporate registry information, and medical facility registries. While valuable for quantitative finance, AI research, and other industries, working with these raw datasets is challenging due to encoding issues, imperial era date formats, merged cells, and disparate identifiers.
The Japan Open Data Lab has streamlined this process by converting 155+ datasets into a consistent US Federal & SEC 24-column schema, unified by National Tax Agency Corporate Numbers and JIS Municipal Codes. The lab has published several showcase samples on Hugging Face and a Google Colab recipe that allows users to query the data in real-time, all without downloading any files.
Using DuckDB's HTTP Parquet reader, analysts can perform complex queries across multiple tables in milliseconds, even with multi-megabyte datasets. Examples include analyzing the top government contractors, joining government tender winners with corporate registry data, and exploring historical land valuations. For those seeking production-grade data, the Japan Open Data Lab offers a free RapidAPI Hub tier with DuckDB SQL execution capabilities and a commercial MEGA tier for more extensive access.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
