Furigana, romaji, wareki dates, full-width text, JP phone formatting — the Japanese input layer for global SaaS, commerce and fintech. Pure edge logic, no round-trips.
Full-width characters, kana, wareki dates, name readings — the parts of Japanese that Western validation APIs miss. formfit handles them, on the edge, so you don't need Japanese-market expertise on your team.
Furigana, romaji (Hepburn/Kunrei), wareki⇄Gregorian, full-width normalization, JP phone & corporate numbers. The Japanese-input correctness your team doesn't have to build.
Runs on Cloudflare Workers, close to every user. Pure logic — no external database or API lookups — so it answers fast enough to call on every keystroke, worldwide.
Every endpoint under a single API key, metered and billed as one. Turn on more of the suite without a new contract or integration.
We only quote numbers we've measured. TTFB to the production API (a real 200 validation response) from a consumer connection in Tokyo:
curl -s -o /dev/null -w "%{time_starttransfer}s\n" \
-H "Authorization: Bearer YOUR_API_KEY" \
"https://formfit.dev/api/v1/phone/validate?number=090-1234-5678"
Measured 2026-07-06, Tokyo, median of n=20. Edge execution with zero external I/O — latency stays flat under load. Your numbers will vary by network and region; the command above lets you verify anytime.
Highlighted = Japanese-specific, where formfit is uniquely strong. The rest are the universal validators you'd expect — so one key covers the whole form.
REST. One request, one job. Single or batch (up to 1,000), same shape.
GET /api/v1/romaji?text=やまだたろう&system=hepburn
# or POST a batch
POST /api/v1/normalize
{ "texts": ["ＡＢＣ１２３", "ｶﾀｶﾅ"] }{
"success": true,
"data": {
"romaji": "yamadatarou",
"system": "hepburn",
"unresolved": []
}
}A single API key unlocks all 13 APIs; usage is metered across formfit as one line (domain-unified billing).
Start free with 1,000 req/day. Grab an API key and go from a single curl.
Start free →