How OpenCode and OpenRouter Can Be Used as a Cost-Efficient Coding Powerhouse

The pricing of AI coding tools has gotten out of hand. GitHub Copilot Individual, Cursor Pro, Windsurf — they all make sense if you’re billing clients by the hour and need every productivity boost you can get. But for side projects, open source work, or developers in markets where $20/month is not trivial, there’s a better path.

OpenCode paired with OpenRouter gives you a capable AI coding agent at pay-as-you-go rates that are often 10–20x cheaper than an all-you-can-eat subscription — especially if you’re not in the IDE all day.

What Is OpenCode?

OpenCode is an open-source terminal-based AI coding agent built by the SST team. It works like other coding agents: you describe what you want, it reads your codebase, proposes changes, and applies them. The key difference is that it’s a CLI tool — no Electron app, no browser extension, no subscription. You bring your own model.

It supports any OpenAI-compatible API, which means it works out of the box with OpenRouter.

What Is OpenRouter?

OpenRouter is a model marketplace. One API, one key, access to Claude, GPT-4o, Gemini, Llama, Mistral, Qwen, DeepSeek — every major model. You pay per token at rates often close to (or below) the provider’s direct pricing.

The practical upside: you can switch models without changing your code or config. If Sonnet 3.7 is overkill for a refactor, swap to Haiku. If you need deep reasoning on a complex architectural decision, use Opus. Pay for what you actually use.

Setting It Up

Step 1: Get an OpenRouter API Key

Create an account at openrouter.ai and fund your account. $10 goes a long way — a typical coding session with Claude Sonnet costs $0.05–0.30 depending on how much context gets passed around.

Step 2: Install OpenCode

npm install -g opencode-ai

Or if you’re using Bun:

bun install -g opencode-ai

Step 3: Configure OpenCode to Use OpenRouter

OpenCode uses a opencode.json config file. Create one in your project root or home directory:

{
  "provider": {
    "openrouter": {
      "name": "OpenRouter",
      "baseURL": "https://openrouter.ai/api/v1",
      "apiKey": "YOUR_OPENROUTER_KEY"
    }
  },
  "model": "openrouter/anthropic/claude-sonnet-4-5"
}

Step 4: Run It

opencode

You’re dropped into a TUI where you can chat with the agent, apply diffs, and navigate your codebase.

Which Models Work Best?

From practical use:

The beauty of OpenRouter is that you can mix and match within the same workflow. Start a session with Haiku, escalate to Sonnet when you hit a tricky problem.

The Cost Reality

A Claude Sonnet 3.7 session doing real work (scaffolding a feature, refactoring a module, writing tests) typically uses 50k–200k tokens. At OpenRouter rates:

• Input: ~$0.003 per 1K tokens
• Output: ~$0.015 per 1K tokens

A heavy session: maybe $1–3. Compared to $20/month for Cursor Pro (which you’re also sharing with rate limits), pay-as-you-go wins unless you’re doing 8-hour AI-assisted coding sessions every day.

What OpenCode Does Well

• Full codebase context: it reads files, understands project structure, applies multi-file changes
• Agentic loops: it can run shell commands, check output, fix errors iteratively
• Diff approval workflow: every change is shown as a diff you approve before applying
• No IDE lock-in: works in any terminal, pairs well with Neovim, Helix, or just your editor of choice

Where It Falls Short

• No inline completions (use a separate tool like Supermaven or Codeium for that)
• The TUI takes getting used to if you’re coming from Cursor’s chat panel
• Some tasks that Cursor handles with slash commands require more explicit prompting

The Setup That Works

For most developers, the sweet spot is:

1. OpenCode + Claude Sonnet for agentic tasks (write this feature, refactor this module, add tests)
2. Supermaven free tier for inline completions in the editor
3. A $20 OpenRouter credit that lasts 2–3 months of regular use

That’s a full AI-assisted development setup for roughly $8/month in practice. It requires a bit more configuration than “install Cursor and sign in,” but the flexibility and cost savings are worth it for anyone who cares about those things.

Closing Thought

The best AI coding tool is the one that fits your workflow and doesn’t have you watching a usage meter tick down on an expensive subscription. OpenCode and OpenRouter aren’t perfect, but they’re genuinely capable, completely open, and cheap enough that you won’t think twice before firing up an agent session.

Give it a try on a side project before committing to anything.