Communicate freely in English & Japanese - instantly

Kotobase is a Slack app that instantly adds natural translations to your messages. It helps English and Japanese speakers communicate more smoothly and naturally in Slack.
Add to Slack
*Your messages are never stored. All communication is encrypted and handled securely.

What is Kotobase?

Automatic translations directly in your Slack!

Messages sent in English or Japanese are instantly translated into the other language and displayed right in Slack.

Why it matters?

Does your team face challenges like these?
Japanese team members hesitate to speak up due to language anxiety
English speakers copy-pasting messages into translation tools constantly
Mistranslations damaging trust and clarity within the team
Team discussions becoming overly cautious to avoid misunderstandings

Kotobase eliminates these language-related stresses—right within Slack.

Features

01

Instant translations shown directly in Slack messages

No more copy-pasting into translation tools. Kotobase translates for you—automatically.
02

Natural, human-like interpretations

Unlike literal machine translation, Kotobase captures tone and context for better clarity.
03

Designed for both English and Japanese speakers

Optimized specifically for EN↔JA communication. Everyone in the team can understand each other—right in Slack.

How it works

Set up in minutes—just a few simple steps and you’re ready to go!
Click “Add to Slack”
Add to Slack
Select your workspace and channels
Kotobase will automatically add translations to your messages

Up to 1 million tokens of translation per month, free!

Enough for around 8,000 messages/month for a 10-person team. Perfect for small to mid-sized teams.

Pilot Program:
Join as an Early Partner

Looking for early adopters to help shape Kotobase.

We’re offering select teams unlimited usage and direct access to our product team for 3 months.

Benefits of joining the Pilot Program

Unlimited translation tokens during the trial
(vs. 1M tokens/month for regular users)
Priority access to new features
Your input helps shape the future of Kotobase

Looking for early adopters to help shape Kotobase.

Apply for the Pilot Program
*Limited to the first 10 companies

FAQ & Security

Q. Are my messages stored?
A. Your messages are never stored. They are used only temporarily for translation and are not saved on any server.
Q. Can the developers see our messages?
A. No one, including the Kotobase team, can access or view the content of your messages.
Q. Is communication encrypted?
A. Yes. All communication between Slack, our backend, and the translation API is protected with TLS encryption.
Q. Will OpenAI use my data for training?
A. The data sent to OpenAI for translation is not used to train their models. This setting is strictly controlled.
Q. What permissions does Kotobase require in Slack?
A. Kotobase only accesses the channels you explicitly allow. It will not read private DMs or other workspaces.

Remove language barriers in your team with Kotobase.

Add to Slack