I tried coding in Italian with Claude and it sounds somewhat less professional than in English. Like it uses different language than what you would expect in the context. In the end I felt the result on the work per se was pretty much the same, just his comments sound strange. Thinking about it again, it's probably because Italian developers don't really speak pure Italian between themselves, we use a lot of English words or distorted Italianised English words when talking about software engineering because all the source material we refer to is written in English and for many things we don't even have translations. Then you talk with a LLM and it actually tries to use proper Italian, when human speakers gave up long ago. So it sounds like a humanities scholar talking about software engineering, not like a insider. It is quite entertaining. I wouldn't say it sucks with non English languages by the way, I even tried describing a bug in dialect and was amused that Claude code one-shotted the fix!

> Grok sometimes respond in Russian

Geopolitically speaking this is hilarious.

You mean Claude sucks at Czech. You're extrapolating here. I can name languages that Claude is better at than GPT.

Gemini is the most fluent in the highest number of human languages and has been for years (!) at this point - namely since Gemini 1.5 Pro, which was released Feb 2024. Two years ago.

Claude code (opus) is very good in Polish.

I sometimes vibe code in polish and it's as good as with English for me. It speaks a natural, native level Polish.

I used opus to translate thousands of strings in my app into polish, Korean, and two Chinese dialects. Polish one is great, and the other are also good according to my customers.

Claude is quite good at European Portuguese in my limited tests. Gemini 3 is also very good. ChatGPT is just OK and keeps code-switching all the time, it's very bizarre.

I used to think of Gemini as the lead in terms of Portuguese, but recently subjectively started enjoying Claude more (even before Opus 4.5).

In spite of this, ChatGPT is what I use for everyday conversational chat because it has loads of memories there, because of the top of the line voice AI, and, mostly, because I just brainstorm or do 1-off searches with it. I think effectively ChatGPT is my new Google and first scratchpad for ideas.

Claude is helping me learn French right now. I am using it as a supplementary tutor for a class I am taking. I have caught it in a couple of mistakes, but generally it seems to be working pretty well.