Most web software today is static, serving broad user needs while ignoring long-tail demands. LLMs change this by enabling "Software for One"—custom tools built for individual workflows. Pete Koomen at Y Combinator calls this "Small Software," but sharing and securing these tools remains complex.

A new opportunity emerges for Extensible Software on the web. LLMs lower extension authoring costs, while modern sandboxes reduce deployment complexity and improve security. Apps can have a solid core with user-driven extensions filled in by AI.

Imagine telling your read-it-later app to send long articles to your e-reader, or asking a tool to parse a specific site. Extensions could be shared like Google Docs. Pi exemplifies this with TypeScript extensions triggered by user prompts.

Corporate and support platforms also benefit. Employees could build custom tools with safe data access, while support teams could add buttons or agents for common tasks. The goal: empower non-developers with tailored tools without becoming software engineers.