Japan Patent Office (JPO) has announced that it will start the pilot program to permit the access to patent information via API in April 2022. However, the number of IDs in each entitiy, the number of access, and the accessable information are limited during the pilot period.
In the US and Europe, USPTO and EPO have already provided users with patent inforimation via API. Especially, USPTO permit the access to a wide variety of information via API even now.
https://data.epo.org/linked-data/
It is truly beneficial for users to obatin patent information via API but in my opinion, the next issue is the harmonization of the format of such infromation. Currently, the format of such information is different among coutries. To standarize such data format is time-consuming process for patent practitioners and prevent them from utilizing and analyzing these data. For example, PubMed provides article information through API and these format is well-harmonized even though published journals are different. This reduces the time of data preparation massively and enhaces user avairability and analyzability of such data significantly! I hope patent office in each country will step up effort in harmonizing the format of such data provided by API in the future!
