OpenCode Explained: The Open-Source AI Coding Agent

OpenCode is open source and works with any model, but those are no longer its most interesting features. Model choice is table stakes. What sets OpenCode apart is its architecture, and the trade-offs that come with it, especially if you are coming from Claude Code. In this article, we look at what OpenCode is, what makes its architecture different, what “free” really means once model costs enter the picture, and where its limits sit, focusing on the details that actually affect your decision. What is OpenCode? Project Context: AGENTS.md Instead of CLAUDE.md What is OpenCode? OpenCode is an MIT-licensed coding agent that connects a model you choose to your repository, your terminal, and your tools. Ask it to fix a bug and it can locate the files, draft a plan, edit the code, run the tests, and react to what the tests say. The distinction that clarifies everything else: OpenCode is not a model. The model reads your prompt and produces the response. OpenCode supplies the file tools, shell access, session history, permission rules, and the interface around…