OpenCode + Free AI Models 2026 — The $0 Coding Agent Stack That Rivals Cursor and Copilot

What Is OpenCode?

OpenCode is a terminal-native AI coding agent built by Anomaly (the team behind SST). It launched June 2025 and reached 188,000 GitHub stars by July 2026 — the most popular open-source AI coding agent by a wide margin, with 900+ contributors and 846 releases (latest v1.18.4).

The core philosophy is model agnosticism. Unlike Claude Code (Anthropic-only) or Cursor (a limited model menu), OpenCode treats the agent harness, tool registry, and model provider as independent layers. Start a session with Gemini 3.1 Pro for planning, switch to Kimi K2.5 for implementation, finish with DeepSeek V4 Pro for review — without leaving the terminal. The agent is MIT-licensed TypeScript; the model registry runs on models.dev, a community-maintained catalog of 75+ providers.

OpenCode runs as a local client-server architecture: the agent server handles tool execution, LSP integration, and model communication, while the TUI, desktop app, or IDE extension connects as a client — same session, driven from your terminal, VS Code, or a CI/CD pipeline.

OpenCode Zen: Free Models, Zero API Keys

Zen is Anomaly's curated model gateway — models tested, benchmarked, and verified specifically for coding agents, with correct serving configs confirmed before recommendation. As of July 2026, Zen offers six completely free models, no API key required: DeepSeek V4 Flash Free, Big Pickle, MiMo-V2.5 Free, Laguna S 2.1 Free, North Mini Code Free, and Nemotron 3 Ultra Free. Paid Zen models run at or near provider list price plus a 4.4% + $0.30 fee. Zen Pro ($9.99/mo) unlocks unlimited requests and priority access.

# 1. Install OpenCode
❯ curl -fsSL https://opencode.ai/install | bash
# 2. Launch and connect Zen
❯ opencode
❯ /connect
# 3. Select a free model
❯ /models
# pick: opencode/deepseek-v4-flash-free

The Free Model Lineup — Ranked

Tested across full-stack apps, API refactors, bug hunts, and code reviews. Ranked best overall to situational specialist.

OpenCode vs Cursor vs Copilot vs Claude Code

How to Set Up DeepSeek V4 Pro

Two paths: via Zen (simpler, unified billing) or the direct DeepSeek API (cheaper, $0.435/M input with the permanent 75% discount).

Path A — via OpenCode Zen

# in the OpenCode TUI:
❯ /connect
# select "OpenCode Zen", sign in, paste API key
# switch to DeepSeek V4 Pro:
❯ /model opencode/deepseek-v4-pro

Path B — direct DeepSeek API (cheapest)

// get an API key from platform.deepseek.com, then:
{
  "model": "deepseek/deepseek-v4-pro",
  "providers": {
    "deepseek": {
      "baseURL": "https://api.deepseek.com/v1",
      "apiKey": "${DEEPSEEK_API_KEY}"
    }
  }
}

Connect Local Models via Ollama

For HIPAA, PCI DSS, air-gapped environments, or just full control, OpenCode connects directly to Ollama — your code never leaves the machine. You'll want a 70B+ class model for reliable tool-calling; smaller models hallucinate function arguments.

# 1. pull and run a model
❯ ollama pull qwen3:72b
# 2. configure OpenCode
{
  "model": "ollama/qwen3:72b",
  "providers": {
    "ollama": {
      "type": "openai-compatible",
      "baseURL": "http://localhost:11434/v1",
      "apiKey": "ollama"
    }
  }
}
# ⚠ critical: raise Ollama's default 4K context — too small for tool calls
❯ ollama run qwen3:72b
❯ /set parameter num_ctx 32768
❯ /save qwen3:72b-32k

The Model Chaining Workflow

OpenCode's model-agnostic architecture enables what no other agent matches: different models for different phases, each optimized for its task.

No single model is best at everything: Gemini's 1M context wins for reading whole codebases, Kimi's frontend specialization beats models costing 10× more, DeepSeek's 80.6% SWE-bench catches bugs others miss, and MiniMax at $0.30/M is cheap enough to run on every commit.

Build vs Plan: Two Agents, Zero Risk

Toggle with Tab. Plan mode is read-only — reads files, searches the codebase, proposes changes, but can't edit or run commands without permission. Start every session here. Build mode is full-access — file edits, shell commands, MCP tools. Workflow: Plan first, read the proposal, press Tab, let it build.

There's also a general subagent (@general) for complex multi-step searches, and an explore subagent — cheap, read-only, for fanning out file searches without burning expensive tokens. Custom subagents live in .opencode/agents/ with their own model, tools, and prompt.

LSP Integration

OpenCode spawns Language Server Protocol servers and feeds real compiler diagnostics back to the model after every edit — when it introduces a type error, it sees the error and self-corrects. Claude Code doesn't have this; Cursor has partial support. OpenCode covers 18+ languages out of the box.

Builder.io's testing found OpenCode produced more thorough output than Claude Code (94 tests vs 73) — the LSP loop adds overhead but catches more errors, a tradeoff worth it for production work.

{
  "lsp": {
    "typescript": { "command": ["typescript-language-server", "--stdio"] },
    "go": { "command": ["gopls"] },
    "rust": { "command": ["rust-analyzer"] }
  }
}
// or enable all 25+ built-in servers:
{ "lsp": true }

Your Code Stays Yours

OpenCode never proxies your code — requests go directly from your machine to the LLM provider you choose. No OpenCode server sits in the middle. Session history lives locally in SQLite. No telemetry, no training on your code, no account required for the core tool.

Pair OpenCode with Ollama for maximum privacy — suitable for HIPAA, PCI DSS, defense, and air-gapped work. For cloud models, you choose which provider sees which code: GPT-5 Nano for sensitive projects, DeepSeek V4 Pro for everything else.

Pros & Cons

The $0 Stack vs the Competition

A solo dev running Cursor Pro ($20) + Copilot ($10) + occasional Claude API (~$15) spends roughly $45/month — $540/year, before model API costs. The OpenCode stack: $0 for the agent, $0 for free Zen models, and even a heavy month on DeepSeek V4 Pro's direct API (~10M input tokens) runs about $4.35.

Frequently Asked Questions