Comparison
Kaku vs. Grammarly and DeepL Write
Three tools, three different jobs. Here's where Kaku fits if your goal is writing better Japanese — and learning as you go.
Grammarly is built for English. DeepL Write rewrites text for fluency. Kaku is the only one focused on Japanese grammar, particles, and keigo — correcting you in any desktop app and explaining every fix in plain English so you actually learn the rule.
| Capability | Kaku | Grammarly | DeepL Write |
|---|---|---|---|
| Japanese grammar & particle check | Yes | English-focused | Rewrite only |
| Keigo & politeness correction | Yes | No | No |
| Plain-English explanations | Every fix | English only | No |
| Japanese tone registers (普通体・丁寧語・ビジネス丁寧語) | 3 registers | No | Limited |
| Works in any desktop app | System-wide | Apps & browser | Editor & paste |
| On-device correction | Yes | Cloud | Cloud |
| macOS & Windows | Yes | Yes | Yes |
| Free tier | Yes | Yes | Yes |
Comparison reflects each product's publicly documented capabilities and is current as of the page's last update. Grammarly and DeepL are trademarks of their respective owners; Kaku is not affiliated with either.
Why writers pick Kaku for Japanese
You learn, not just fix
Every correction comes with a plain-English reason, so the rule sticks for next time.
Built for keigo
Particle and politeness mistakes — the parts that trip up learners and natives alike — are Kaku's core focus.
Everywhere you type
Mail, Slack, Notion, browser — Kaku works system-wide, not just in one editor or tab.