OpenCode
Open-source AI coding agent with terminal integration
Quick Take: OpenCode
OpenCode is the best open-source, provider-agnostic AI coding agent available in 2026. It's not as polished as Claude Code and its capabilities depend on which model you plug in, but the flexibility of choosing (and switching) between AI providers — including fully local, private models — makes it a compelling choice for developers who don't want vendor lock-in. If you already have API keys for one or more providers, OpenCode costs nothing to try and nothing to keep using.
Best For
- •Developers who want multi-provider AI flexibility
- •Privacy-conscious developers using local models
- •Budget-conscious developers who prefer API pay-per-use over subscriptions
- •Open-source advocates who want transparent AI tooling
Install with Homebrew
brew install --cask opencode-desktopWhat is OpenCode?
OpenCode is an open-source, terminal-based AI coding agent. Think of it as the community's answer to Claude Code and Codex — a tool that sits in your terminal, reads your codebase, and writes code based on your instructions. You describe what you want built or changed, and OpenCode edits files, runs commands, and iterates until the task is done. The project is written in Go and designed as a TUI (terminal user interface) application. You run `opencode` in a project directory, and it presents a chat interface where you can describe tasks in natural language. Behind the chat, OpenCode has file system access — it can read your code, create new files, modify existing ones, and run shell commands. It uses LLMs (Claude, GPT-4, Gemini, or any OpenAI-compatible API) to understand your codebase and generate code changes. What makes OpenCode interesting is its multi-provider approach. Unlike Claude Code (locked to Anthropic) or GitHub Copilot (locked to OpenAI), OpenCode works with any LLM provider that exposes an OpenAI-compatible API. You can point it at Ollama for local inference, OpenRouter for model marketplace access, or directly at Anthropic, OpenAI, or Google's APIs. This flexibility means you're not locked into one provider's pricing or availability. The TUI interface is well-designed for a terminal app: syntax-highlighted code diffs, file tree navigation, command execution output, and a conversation history. It feels like a focused coding tool rather than a generic chat interface. The agent can handle multi-file edits, create new files, run tests, and iterate based on error output — similar to what Claude Code does but with the transparency and flexibility of open source. OpenCode is early-stage software. It's functional and actively developed, but it doesn't have the polish or reliability of Claude Code or Cursor's Composer. The advantage is openness: you can see exactly what it does, modify its behavior, and contribute improvements. For developers who want an AI coding agent without vendor lock-in, OpenCode is the most promising open-source option.
Deep Dive: The Open-Source AI Coding Agent Movement
How OpenCode and similar projects are providing vendor-independent alternatives to commercial AI coding tools.
History & Background
The AI coding agent category exploded in 2024-2025 with Claude Code, Codex, and Cursor establishing the category. But all of these are commercial, vendor-locked tools. OpenCode emerged from a group of developers who wanted the same capabilities without the lock-in. The Go codebase started as a simple CLI wrapper around API calls and rapidly grew into a full-featured coding agent with file editing, command execution, and TUI.
How It Works
OpenCode is written in Go and compiles to a single binary with no dependencies. The architecture is modular: a 'provider' layer abstracts different AI APIs, a 'tools' layer handles file operations and command execution, and a 'UI' layer renders the TUI using the Bubble Tea framework. Adding a new AI provider means implementing a simple interface — the community has added providers for over a dozen services. The session state is stored locally in JSON files, making it easy to inspect and debug.
Ecosystem & Integrations
OpenCode sits in a broader ecosystem of open-source AI coding tools. Goose (by Block), Aider, and Continue are similar projects with different approaches. OpenCode differentiates with its clean Go binary (no Python runtime needed) and its TUI-first design. Community plugins are starting to appear for custom tools — code review assistants, documentation generators, and test writers.
Future Development
The project's roadmap includes better context management (smarter file selection to stay within context windows), conversation branching (try multiple approaches and compare), MCP (Model Context Protocol) support for tool extensions, and improved diff handling for complex multi-file changes.
Key Features
Multi-Provider Support
OpenCode supports OpenAI (GPT-4o, GPT-4.1), Anthropic (Claude Sonnet, Claude Opus), Google (Gemini), Groq, and any OpenAI-compatible API endpoint. This includes local models via Ollama or LM Studio. You configure providers in a YAML config file and can switch between them mid-session. This is the feature that most differentiates OpenCode from Claude Code and Codex.
Codebase Awareness
OpenCode reads your project's file structure, indexes key files, and builds context from your codebase. When you ask it to 'add error handling to the API routes,' it finds the relevant files, reads them, and generates contextually correct changes. The depth of codebase awareness depends on the model's context window — Claude's 200K tokens handle larger projects than GPT-4o's 128K.
File Creation and Editing
OpenCode can create new files and edit existing ones. Changes are shown as diffs that you approve or reject before they're written to disk. For multi-file changes (like adding a new feature that touches 5 files), the agent plans the changes and presents them as a batch. The diff view uses standard unified diff format that's easy to scan.
Command Execution
The agent can run shell commands — running tests, installing packages, building projects, checking git status. Commands are shown for approval before execution. This means you can say 'run the test suite and fix any failures' and OpenCode will execute `npm test`, read the error output, identify the failing tests, and generate fixes.
Terminal UI (TUI)
OpenCode runs in your terminal with a clean text-based interface built with Bubble Tea (a Go TUI framework). The interface shows the conversation, file changes with syntax-highlighted diffs, command outputs, and tool usage. It's not a raw REPL — it's a structured interface that organizes the agent's work into readable sections.
Open Source and Extensible
The entire codebase is open source (MIT License) on GitHub. You can inspect how the agent works, contribute features, fix bugs, or fork it for your own needs. The project uses Go, making it a single compiled binary with no runtime dependencies. Community contributions are active, with regular PRs adding new providers and features.
Who Should Use OpenCode?
1The Privacy-First Developer
Working on a proprietary codebase that can't be sent to external APIs, this developer configures OpenCode to use a local Llama 3.1 70B model running through Ollama. All code stays on their machine — no data leaves the network. The local model isn't as capable as Claude or GPT-4o, but for focused tasks like writing tests, refactoring functions, and generating boilerplate, it works well enough. No vendor lock-in, no data privacy concerns.
2The Model Experimenter
This developer evaluates different AI models for coding tasks. They configure OpenCode with three providers: Anthropic for complex multi-file refactoring, OpenAI for quick code generation, and Groq for fast responses on simple questions. They switch between models depending on the task, comparing output quality and response time. OpenCode is their testbed for finding the best model for each type of coding work.
3The Open-Source Contributor
Contributing to open-source projects, this developer doesn't want to pay for Claude Pro or Codex subscriptions just for occasional AI assistance. They use OpenCode with their existing OpenAI API key (pay-per-use) and switch to free local models for simple tasks. The total cost is a few dollars per month in API calls, versus $20+/month for Claude Pro.
How to Install OpenCode on Mac
OpenCode is distributed as a Go binary. Install via Homebrew or download directly from GitHub releases.
Install via Homebrew
Run `brew install opencode-ai/tap/opencode`. This installs the latest stable binary.
Configure a Provider
Create `~/.config/opencode/config.yaml` and add your API key. For Anthropic: set `provider: anthropic` and `api_key: sk-ant-...`. For OpenAI: set `provider: openai` and `api_key: sk-...`. For local Ollama: set `provider: ollama` and `base_url: http://localhost:11434`.
Navigate to Your Project
cd into your project directory. OpenCode reads the current directory as the project root.
Launch OpenCode
Run `opencode` in your terminal. The TUI opens with a prompt. Start typing natural language instructions — 'explain this codebase,' 'add input validation to the login form,' 'write tests for the user service.'
Pro Tips
- • Set the ANTHROPIC_API_KEY or OPENAI_API_KEY environment variable in your .zshrc for automatic provider detection without a config file.
- • Use `opencode --model claude-sonnet-4-20250514` to specify a model directly from the command line.
- • For large codebases, create a `.opencode-ignore` file (same syntax as .gitignore) to exclude directories from context indexing.
Configuration Tips
Optimize for Large Codebases
Create a `.opencode-ignore` file in your project root to exclude node_modules, .git, build directories, and large data files. This reduces the context the agent needs to process and improves response quality by focusing on relevant code.
Use Different Models for Different Tasks
Configure multiple providers and switch between them. Use Claude Sonnet for complex multi-file refactoring (best reasoning). Use GPT-4o-mini for quick documentation generation (fast and cheap). Use a local model for sensitive codebases. The `--model` flag lets you switch on a per-session basis.
Alternatives to OpenCode
OpenCode competes with both commercial and open-source AI coding agents.
Claude Code
Claude Code is Anthropic's official terminal-based coding agent. It's more polished, more capable (built specifically for Claude's strengths), and has better codebase understanding. But it's locked to Anthropic and requires a Claude Pro subscription. OpenCode gives you model flexibility and costs only what you use in API calls.
Codex
Codex is OpenAI's autonomous coding agent that runs tasks in cloud sandboxes and delivers pull requests. It's a different model — delegation vs. interactive coding. OpenCode is interactive and terminal-based, like Claude Code. Codex is fire-and-forget. Choose based on how you want to work with AI.
Goose (Block)
Goose is another open-source AI coding agent with multi-provider support. It uses an 'extension' system for tools (git, shell, file editing) and has a session-based architecture. OpenCode and Goose are similar in philosophy; the choice comes down to interface preference and which project's approach resonates with you.
Pricing
OpenCode itself is completely free and open source (MIT License). You pay only for the AI model usage through your chosen provider's API pricing. Using Anthropic's Claude costs roughly $3-15 per million tokens depending on the model. Using local models via Ollama costs nothing. There are no OpenCode subscription fees, no premium tiers, and no feature gates.
Pros
- ✓Multi-provider support — not locked to any single AI vendor
- ✓Works with local models (Ollama) for complete privacy
- ✓Completely free and open source (MIT License)
- ✓Single binary — no runtime dependencies, fast startup
- ✓Clean terminal UI with diff previews and command approval
- ✓Active open-source development with community contributions
- ✓Pay-per-use API costs vs monthly subscriptions
Cons
- ✗Agent quality depends heavily on the underlying model
- ✗Less polished than Claude Code's dedicated experience
- ✗Smaller community and fewer examples compared to commercial tools
- ✗Local models are significantly less capable than Claude or GPT-4o
- ✗No IDE integration — terminal only
- ✗Documentation is sparse compared to commercial alternatives
Community & Support
OpenCode has a growing open-source community on GitHub (github.com/opencode-ai/opencode). The project is written in Go and welcomes contributions. Support happens through GitHub Issues and Discussions. The Discord server is active with users sharing configurations, provider comparisons, and workflow tips. Documentation is a work in progress — the README and CLI help text cover the basics, but in-depth guides are still being written by the community.
Frequently Asked Questions about OpenCode
Our Verdict
OpenCode is the best open-source, provider-agnostic AI coding agent available in 2026. It's not as polished as Claude Code and its capabilities depend on which model you plug in, but the flexibility of choosing (and switching) between AI providers — including fully local, private models — makes it a compelling choice for developers who don't want vendor lock-in. If you already have API keys for one or more providers, OpenCode costs nothing to try and nothing to keep using.
About the Author
Related Technologies & Concepts
Related Topics
AI Coding Agents
Terminal-based AI tools that read codebases and implement changes.
Sources & References
Fact-CheckedLast verified: Feb 23, 2026
- 1OpenCode GitHub Repository
Accessed Feb 23, 2026
Research queries: OpenCode AI coding agent Mac 2026