Keigo Converter

Mode

Polite: converts plain/casual endings into desu/masu style 🎭 For jokes only. Don't use this in real business.

Input (casual Japanese text)

Paste Japanese text — this tool converts Japanese only 0 chars

Loading the analysis dictionary…
First time only. The dictionary also runs in your browser; nothing is uploaded.

Fetching dictionary data 0%

Failed to load the analysis dictionary Please check your connection. Retry

Running in simple mode Dictionary replacement only (no conjugation-aware sentence-ending conversion)

Output (keigo draft)

The converted text will appear here

The result is a draft. Correct keigo depends on the person and situation — always review before sending.

NG phrase check

No NG phrases found This is a mechanical check and may miss things. Please do a final review yourself.

Cushion phrase suggestions

How to use

1 Paste casual Japanese text

2 Pick a mode (Polite / Business / Over-polite)

3 Convert → review the result and NG check → copy

Business mode assumes you are the subject (humble form). The result is a draft — always review it before sending. Your text is processed entirely in your browser and never sent anywhere.

Features

Three conversion modes

Polite (desu/masu), Business (humble & honorific vocabulary), and an over-polite parody mode.

Business NG-phrase checker

Detects risky phrases like 「了解しました」 and suggests safer alternatives. Can also be used as a checker only.

Nothing ever leaves your browser

Runs on an in-browser dictionary and morphological analyzer — safe even for business email drafts.

Conjugation-aware conversion

kuromoji.js analyzes sentence endings for natural conversions like 行く → 行きます.

Use cases

Email drafts to your boss or clients

Quickly turn a casual note into a draft suitable for superiors or external contacts.

Politer chat replies in a hurry

Paste a Slack or LINE reply and make it polite in one click.

Self-check before sending

Use “Check only” to scan a finished email for NG phrases without converting it.

Over-polite jokes for social media

Turn everyday phrases into absurdly excessive keigo for laughs.

FAQ

Can I send the converted text as-is?

The result is a draft. Correct keigo depends on the person and situation, so always review it before sending.

Is my text uploaded anywhere?

No. Conversion and checking are fully in-browser; not a single character reaches a server. The analysis dictionary also runs in your browser.

Is 「了解しました」 rude?

It is commonly considered safer to avoid it with superiors. 「承知しました」 or 「かしこまりました」 are the standard alternatives — the NG checker detects this automatically.

How are honorific and humble forms used?

Honorific forms (いらっしゃる) are for the other person as subject; humble forms (伺う) are for yourself. Since software cannot determine the subject, Business mode assumes you are the subject and leaves ambiguous words unconverted.