You can manually create one

https://www.w3.org/community/bigdata-tools/files/2017/10/HAR_Spec_TO_HAR_Vocabulary.pdf https://confluence.atlassian.com/kb/generating-har-files-and-analyzing-web-requests-720420612.html http://www.softwareishard.com/blog/har-12-spec/

Can be viewed in chrome devtools