A monolingual team can ship for years without hitting the bugs that lose them Japanese users on day one. I kept finding the same five gaps while looking at foreign dev-tools, so I turned the check into a CLI.

Run it

npx github:greymoth-jp/jp-ready-check your-site.com

No install, no account. It fetches the page once and scores it 0–5.

What it checks

1. hreflang ja — without it, Google.co.jp / Yahoo! Japan can't reliably surface your Japanese pages.
2. A Japanese locale path / switcher — the ja content often exists, but nothing links to it, so Japanese users never reach it.
3. 特商法 (Tokushoho) page — the legal disclosure Japanese buyers expect when paying for an online service. Its absence reads as "not set up to sell here."
4. JPY pricing — USD-only reads as "you're not our market."
5. Japanese content at all — whether there's any lang="ja" / Japanese text on the page.

What it can't check (on purpose)

The most common real breakage is an IME/CJK input bug — an Enter that confirms a Japanese conversion getting treated as "submit." That needs a runtime test, not an HTML scan. (I wrote about that class of bug here.)

So a passing score is necessary, not sufficient — but a failing score is a fast, honest signal that the funnel isn't speaking Japanese yet.

Why I built it

I'm a Tokyo-based dev, and Japan has unusually high SaaS ARPU — but the path from "the product could work in Japanese" to "a Japanese buyer trusts it" is full of these quiet, controllable gaps. I scored 13 open-source dev-tools on these dimensions, each gap linked to a real GitHub issue or live URL: https://jp-ready.glovrex.com

Want the deep version verified against your live site? https://glovrex.com/check

MIT-licensed — fold the checks into your own CI if useful: https://github.com/greymoth-jp/jp-ready-check