[Indie Dev] Introducing RakuChat LINE Translator: An AI-Powered Translation Bot

So, what did I build?

I created a LINE translation app called RakuChat LINE Translator.

The AI understands the context of your chat and translates your LINE messages accordingly. Unlike traditional machine translation apps, I've differentiated this app by adding support for languages where wording changes based on the speaker's gender (like Thai or Russian) and allowing you to select the tone of the translation (casual, formal, etc.).

Isn't Google Translate enough?

Nope. Take a look at this.

This is a real-life comedy of errors with my girlfriend.

Translation

• 🙎‍♂️: (She's late. I'll text her.) You okay?
• 🥰: I'm at my parents'. Also mother can't go home.
• 🙎‍♂️: (I have no idea what that means, but I'll reply for now.) As long as you're safe, that's fine.
• 🥰: OK. I return sometimes.
• 🙎‍♂️: (Wait, hold on. What on earth does "mother can't go home" mean?)
• 🙎‍♂️: Sorry, what do you mean "mother can't go home"?
• 🥰: I go~
• 🥰: 🛵

Do you understand this chat? I didn't. She probably meant she was at her parents' house, but I never found out what she wanted to say with "my mother can't go home" before she rode off on her scooter. (She came back later as if nothing had happened).

My girlfriend is Thai but speaks English. Reading and writing aren't her strong suits though, so she often uses Google Translate for LINE messages. Sometimes, those translations land in the "unintelligible" zone. This was just one example. I'm sure I'm not the only one who has experienced this kind of lost-in-translation moment.

So I thought, "If there isn't an app that can solve this problem, I'll just build it myself." And that’s how this translation app was born.

So, do I have to pay?

Yes, you do! I poured my professional skills and experience into this, chipping away at it on nights and weekends. I do expect compensation for my work. Plus, there are costs for servers and translation APIs.

However! I have prepared a free tier!

I also managed to lower the price of the Pro plan to just $2.90/month. There's also a credit plan for flexible usage. You can start from as little as $2, so it's easy for those who just want to try it out.

I have prepared 3 plans to suit different needs.

It's an indie app, is it safe?

Rock solid. Security is actually one of my main areas of expertise in my day job. I've implemented cyber attack countermeasures comparable to those of a medium-sized enterprise.

In 2025 alone, I prevented 3 cyber attacks at my company (My company gets attacked a lot, seriously...). We are a two-person team, and I'm one of them. Industry folks might be surprised to hear that we look after over 100 OS instances across physical servers and VMs in different data centers and clouds. Honestly, I was surprised too when I joined.

(A bit more detail for the tech-savvy...) We dealt with 3 DDoS attacks: 2 were Credit Master (Carding) attacks and 1 was a SYN Flood. I had to tweak kernel settings to manage them. It was chaotic—we tightened restrictions so much that we started blocking legitimate users, too. Simply installing a WAF isn't always the solution. I'll save the tearful details of that story for another time.

Do you peek at my chats?

No! But please check the Terms of Service and Privacy Policy before using the app. We only temporarily store the last 3-5 exchanges for 24 hours. This is solely to allow the AI to understand the context of the recent conversation.

Whether used for context understanding or not, they are promptly deleted after 24 hours.

Is it just for text translation?

It also has a voice translation feature, which other LINE translation apps don't usually have. Voice messages might not be very common in Japan, but they are frequently used in certain regions, so I included this feature.

I tested it with a conversation in English, Thai, and Japanese. It also supports one-to-many group conversations.

Hmm. Actually sounds pretty good?

Thank you! I've experimented with AI token usage to keep it low and optimized server costs. I'm offering a LINE translation app that is cheaper and higher performance than existing alternatives.

Using AI, we achieve translations that sound natural to native speakers.

As mentioned, there is a free tier, so please give it a try! Below is the link to add it as a friend. I'd appreciate it if you shared it with friends or acquaintances who might find this app useful!

Since it's just been released, there's probably still room for improvement. Also, as of December 6, 2025, this LINE account is actually not yet verified (currently preparing for application). You might encounter some bugs. I will address any bugs sincerely and quickly. I hope you'll watch over the project warmly.