Smol Developer is an open-source Python library from Smol AI that lets you embed a capable software-developer agent directly inside your own application. Instead of chatting with a standalone coding assistant, your program can hand the library a natural-language prompt and receive back a complete, structured codebase, generated file by file. It began as a viral experiment in 2023 and became one of the first widely used “AI developer” libraries.
The library works by orchestrating an LLM through the same steps a human developer would take: it plans the file layout, writes each file with awareness of the others, and can debug and refine the result. Developers interact with it through a simple Python API, making it easy to build code-generation features into scripts, internal tools, or larger agent systems. The project has gathered over 12,100 GitHub stars, was last updated in April 2024, and is released under the permissive MIT license. Because the intelligence comes from the model you connect, Smol Developer focuses on the scaffolding: prompt structure, file management, and the generate-debug loop that turns a one-line idea into a working project skeleton.
Smol Developer is completely free and open source under the MIT license. You only pay for the LLM API calls your own application makes to the model provider you choose.
Developers building AI coding features into their own apps, indie hackers prototyping products quickly, and researchers experimenting with autonomous software-generation agents.