What programming language(s) does it know?
That's a good question. I just started writing my personal apps in Python and never thought to ask that question. I was just after simple apps I can run in Terminal from the CL. So I asked Claude itself "What programming languages can Claude Code generate?" It replied:
Claude Code doesn't restrict you to any particular language — it works across a very broad range. Here's a breakdown:I've had Claude write lots of comments in the code and they are very good. Well structured, well organized, thorough. I've had it write instruction manuals and Project State documents. The documentation it generates is very good.Core strengths (best performance, most training data): Python, JavaScript, TypeScript, Java, C++, C#, Ruby, Go, Rust, and SQL
Also well supported: PHP, Swift, Kotlin, Scala, R, Bash, PowerShell, and HTML/CSS
Specialized and infrastructure languages: R (statistics), Scala (data engineering), Clojure (functional), Haskell (type-safe systems), LISP dialects, configuration languages (YAML, TOML, JSON), and Infrastructure-as-Code tools like Terraform, CloudFormation, and Kubernetes manifests
Beyond code: Documentation formats like Markdown and reStructuredText, markup like HTML and XML, and query languages like GraphQL and SQL
A note on quality: The languages Claude Code handles best are those with abundant training data (Python, JavaScript, Java, Go), clear syntax, and established testing frameworks. For niche languages with limited open-source representation, accuracy decreases — but even for esoteric languages, fundamental programming knowledge like algorithms, design patterns, and concurrency models transfers well.
In short, if it's a mainstream language, Claude Code will handle it well. For more obscure languages (COBOL, Fortran, VHDL), it can still help with basics but may be less reliable.
One thing I forgot to mention is I've had it write VBA macros for Excel, too. It has done an outstanding job there, knows a lot of the bugs in Excel and how to work around them. There are often multiple ways to solve a problem in Excel and VBA and it will choose the optimal solution. The limitations on the Windows and Mac platforms are different, too, so it chooses the best solution for the platform (I use Mac). I was initially using Grok to write VBA and it was awful. It would generate a solution that did not work, did not understand Excel limitations or platform constraints. I would tell it "No, here's the problem with your code" and it would pursue another approach. When that one didn't work, it went back to the original failed approach! Claude has never done that.
Claude wrote "For more obscure languages (COBOL, Fortran)." LOL. I grew up on FORTRAN.