OpenCode: The Open Source Claude Code Alternative (2026)

OpenCode: The Open Source Claude Code Alternative (2026)

Claude Code is Anthropic's official terminal-based AI coding assistant. It is powerful, but it is closed-source and locked to Anthropic's API. OpenCode is an open-source alternative that gives you the same terminal AI coding experience with any LLM provider.

This guide covers what OpenCode is, how to set it up, and how it compares to Claude Code.

What Is OpenCode?

OpenCode is an open-source, terminal-based AI coding assistant built in Go. It provides an interactive TUI (terminal user interface) for AI-assisted coding directly in your terminal, similar to Claude Code.

Key features

• Open source (MIT license)
• Multi-provider support: OpenAI, Anthropic, Google, Groq, local models
• Terminal UI: Rich interactive interface with syntax highlighting
• File editing: AI can read, create, and modify files
• Shell commands: AI can execute terminal commands
• Session management: Save and resume coding sessions
• LSP integration: Language Server Protocol for better code understanding
• Git-aware: Understands your repository context
• Custom tools: Extend with your own tool definitions

Installation

Using Go

go install github.com/opencode-ai/opencode@latest

Using Homebrew (macOS)

brew install opencode

Using curl (Linux/macOS)

curl -fsSL https://opencode.ai/install.sh | sh

From source

git clone https://github.com/opencode-ai/opencode.git
cd opencode
go build -o opencode .
mv opencode /usr/local/bin/

Verify installation

opencode --version

Configuration

OpenCode uses a configuration file at ~/.config/opencode/config.json or a project-level opencode.json.

Basic configuration

{
  "provider": "anthropic",
  "model": "claude-sonnet-4-20250514",
  "apiKey": "your-anthropic-api-key",
  "mcpServers": {}
}

Multi-provider configuration

{
  "providers": {
    "anthropic": {
      "apiKey": "sk-ant-...",
      "models": ["claude-sonnet-4-20250514", "claude-opus-4-20250514"]
    },
    "openai": {
      "apiKey": "sk-...",
      "models": ["gpt-4o", "gpt-4o-mini"]
    },
    "google": {
      "apiKey": "AIza...",
      "models": ["gemini-2.5-pro", "gemini-2.5-flash"]
    },
    "ollama": {
      "baseUrl": "http://localhost:11434",
      "models": ["phi4", "qwen2.5-coder:7b", "llama3.3:70b"]
    }
  },
  "defaultProvider": "anthropic",
  "defaultModel": "claude-sonnet-4-20250514"
}

Environment variables

# Set API keys via environment variables
export ANTHROPIC_API_KEY="sk-ant-..."
export OPENAI_API_KEY="sk-..."
export GOOGLE_API_KEY="AIza..."

# Or use a .env file in your project root

Basic Usage

Start OpenCode

# Start in current directory
opencode

# Start with a specific provider/model
opencode --provider openai --model gpt-4o

# Start with a prompt
opencode "Explain the architecture of this project"

# Start in a specific directory
opencode --dir /path/to/project

Interactive TUI

Once launched, OpenCode presents a terminal interface:

┌─ OpenCode ──────────────────────────────────────────────┐
│                                                          │
│  Assistant: I can see this is a Next.js project with     │
│  TypeScript. How can I help?                             │
│                                                          │
│  Files in context:                                       │
│  - package.json                                          │
│  - tsconfig.json                                         │
│  - src/app/page.tsx                                      │
│                                                          │
├──────────────────────────────────────────────────────────┤
│  > Add a dark mode toggle to the header component        │
│                                                          │
└──────────────────────────────────────────────────────────┘

Key commands

Command	Description
Type + Enter	Send a message
/help	Show available commands
/model <name>	Switch model mid-session
/clear	Clear conversation history
/compact	Summarize conversation to save context
/files	List files in context
/quit or Ctrl+C	Exit OpenCode
/session list	List saved sessions
/session load <id>	Resume a previous session
/undo	Undo last file change
/diff	Show pending file changes

Features Deep Dive

File editing

OpenCode can read and modify files in your project. It shows diffs before applying changes:

You: Add input validation to the signup form in src/components/SignupForm.tsx

OpenCode: I'll add validation. Here's the diff:

--- src/components/SignupForm.tsx
+++ src/components/SignupForm.tsx
@@ -15,6 +15,20 @@
 export function SignupForm() {
+  const validateEmail = (email: string): boolean => {
+    return /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email);
+  };
+
+  const validatePassword = (password: string): string[] => {
+    const errors: string[] = [];
+    if (password.length < 8) errors.push("Min 8 characters");
+    if (!/[A-Z]/.test(password)) errors.push("Need uppercase");
+    if (!/[0-9]/.test(password)) errors.push("Need number");
+    return errors;
+  };

Apply this change? [y/n]

Shell command execution

OpenCode can run terminal commands and use the output for context:

You: Run the test suite and fix any failing tests

OpenCode: Running tests...
$ npm test

> 3 tests failed:
> - auth.test.ts: Expected 401, got 500
> - user.test.ts: Timeout exceeded
> ...

I see the issues. Let me fix them:
[proceeds to edit files]

MCP (Model Context Protocol) support

OpenCode supports MCP servers for extended tool capabilities:

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/allowed/dir"]
    },
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"],
      "env": {
        "GITHUB_TOKEN": "ghp_..."
      }
    },
    "postgres": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-postgres", "postgresql://localhost/mydb"]
    }
  }
}

Custom instructions

Create a .opencode.md file in your project root (similar to Claude Code's CLAUDE.md):

# Project Instructions

## Tech Stack
- Next.js 15 with App Router
- TypeScript (strict mode)
- Tailwind CSS
- Drizzle ORM with PostgreSQL

## Coding Standards
- Use functional components only
- All functions must have TypeScript types
- Use server actions for mutations
- Follow existing naming conventions in the codebase

## Testing
- Write tests for all new functions
- Use Vitest for unit tests
- Use Playwright for E2E tests

OpenCode vs Claude Code

Feature	OpenCode	Claude Code
License	MIT (open source)	Proprietary
Price	Free (BYO API key)	Pay per use (Anthropic API)
Providers	Any (OpenAI, Anthropic, Google, Ollama, etc.)	Anthropic only
Local models	Yes (Ollama, llama.cpp)	No
Terminal UI	Yes	Yes
File editing	Yes	Yes
Shell commands	Yes	Yes
Git integration	Yes	Yes
MCP support	Yes	Yes
Session management	Yes	Yes
Memory/context	Manual (.opencode.md)	Automatic (CLAUDE.md)
Speed	Depends on provider	Fast (Anthropic infrastructure)
Built-in tools	Standard set	Extensive (web search, notebooks, etc.)
IDE integration	Terminal only	Terminal + VS Code extension
Language	Go	TypeScript/Rust

When to use OpenCode

• You want to use models other than Claude (GPT-4o, Gemini, local models)
• You prefer open-source tools you can inspect and modify
• You want to use local LLMs for privacy or offline work
• You want to avoid vendor lock-in
• Budget-conscious: pair with cheaper API providers

When to use Claude Code

• You want the best-in-class coding model (Claude Opus/Sonnet)
• You need the most polished, tested experience
• You want automatic context management
• You rely on advanced features like web search within the tool
• You are already paying for Anthropic API access

Using OpenCode with Local Models

One of OpenCode's biggest advantages is local model support:

{
  "providers": {
    "ollama": {
      "baseUrl": "http://localhost:11434",
      "models": ["qwen2.5-coder:7b"]
    }
  },
  "defaultProvider": "ollama",
  "defaultModel": "qwen2.5-coder:7b"
}

# Start Ollama with a coding model
ollama pull qwen2.5-coder:7b
ollama serve

# Then start OpenCode
opencode

This gives you a completely free, fully offline AI coding assistant.

Advanced Usage

Piping input

# Pipe a file for review
cat src/utils/auth.ts | opencode "Review this code for security issues"

# Pipe git diff for commit message
git diff --staged | opencode "Write a commit message for these changes"

# Pipe error logs
npm test 2>&1 | opencode "Fix the failing tests"

Non-interactive mode

# One-shot mode (no TUI)
opencode --no-interactive "Add JSDoc comments to all exported functions in src/utils/"

# Print output only
opencode --print "Explain the database schema in this project"

Scripting

#!/bin/bash
# Automated code review script

for file in $(git diff --name-only HEAD~1); do
  echo "Reviewing: $file"
  opencode --no-interactive --print "Review $file for bugs, security issues, and code quality"
done

Troubleshooting

Common issues

Issue	Solution
"API key not found"	Set environment variable or add to config.json
"Model not available"	Check provider supports the model name
Slow responses	Switch to a faster model or local provider
"Permission denied" on file edit	Check file permissions, run from project root
Ollama connection refused	Make sure ollama serve is running

Debug mode

# Run with verbose logging
opencode --debug

# Check config
opencode config show

Building AI-Powered Applications

OpenCode and Claude Code are great for writing code, but when your application needs AI capabilities like image generation, video creation, or voice synthesis, you need a dedicated API.

Hypereal AI provides production-ready APIs for AI media generation. Use OpenCode to build your app, then integrate Hypereal's APIs for the AI media features. Sign up for free starter credits to get started.

Conclusion

OpenCode is a capable open-source alternative to Claude Code. Its multi-provider support and local model compatibility make it more flexible, while Claude Code offers a more polished experience with Anthropic's models.

If you value open source, want to use multiple LLM providers, or need offline capability with local models, OpenCode is the clear choice. Install it today and start coding with AI in your terminal.