What programming language was originally used to create Reddit?

Reddit was originally created using Common Lisp.

Steve Huffman and Alexis Ohanian launched Reddit in 2005, and the earliest version of the site was built in Common Lisp, a powerful dialect of the Lisp programming-language family. Lisp’s flexibility made it suitable for quickly developing an early web application, but Reddit’s founders soon encountered a practical limitation: the ecosystem did not provide enough libraries for the features they needed.

The developers therefore rewrote Reddit in Python. Python became the better fit for the growing service because it offered a broader collection of web-development libraries and a larger, more convenient development ecosystem. This history is why Python is associated with much of Reddit’s early and later technology, even though it was not the language used for the original implementation.

Common Lisp itself is older than Reddit by decades. Work toward standardizing it began in 1981, early documentation appeared in 1984, and the ANSI standard was published in 1994. It remains a general-purpose language supporting procedural, functional, and object-oriented programming.