Install OpenCode and Use It Free: OpenCode Zen + OpenRouter (2026)

The annoying part of free AI coding is not the editor. It is the model access. You install a tool, connect a provider, and then discover that the free tier ended last week or the key only works in one region.

This setup reduces that pain. OpenCode is the agent, OpenCode Zen gives you a simple key, and OpenRouter gives you a catalog of models you can switch between. When one free model is rate limited, you move to another instead of waiting.

Step 1: Install Node.js

OpenCode is distributed as an npm package, so install Node.js 18 or newer first. Download the LTS installer from nodejs.org and confirm:

node --version
npm --version

On Windows, close and reopen the terminal after installing Node so the PATH is updated. If npm is not recognized, that is almost always a PATH problem, not an OpenCode problem.

Step 2: Install OpenCode

Install the CLI globally:

npm install -g opencode-ai

Check it:

opencode --version

Then start it inside a project:

opencode

The first run opens the provider setup. You can also trigger it later with:

opencode auth login

Step 3: Create an OpenCode Zen key

Open opencode.ai and open the console. Create an API key for OpenCode Zen and copy it once. Treat it like a password.

Back in the terminal:

1. Run opencode auth login.
2. Choose OpenCode Zen as the provider.
3. Paste the key.

OpenCode stores the credential in its own config directory. You do not need to export an environment variable for the basic setup.

Test it with a small prompt. Ask OpenCode to explain the current folder or list the files. If it answers, the connection is working.

Step 4: Connect OpenRouter

OpenRouter is useful because one key gives you access to many models. Create an account at openrouter.ai, open the keys page, and generate a key.

Connect it the same way:

opencode auth login

Choose OpenRouter and paste the key. If you already have Zen configured, you can keep both providers and switch between them.

Step 5: Pick free models

OpenRouter publishes a free model collection at openrouter.ai/collections/free-models. Free model IDs usually end with :free, for example:

deepseek/deepseek-r1:free

Copy the exact model ID from the page. Do not guess the ID from the display name. A wrong model ID is the most common reason a provider returns an error even though the key is valid.

You can set a default model in opencode.json in your project:

{
  "$schema": "https://opencode.ai/config.json",
  "model": "openrouter/YOUR_MODEL_ID"
}

Use the exact provider and model IDs that OpenCode shows in its model list. If you are unsure, start OpenCode and use the model picker before editing the config file.

Step 6: The free token trick

The trick from the video is not a secret unlimited plan. It is provider hygiene:

• Keep at least two free models configured.
• When one returns a rate limit, switch to the other instead of retrying forever.
• Prefer smaller models for simple edits and save the stronger free models for hard debugging.
• Do not send your entire repository when one file is enough.

Free tiers change without notice. A model that is free today can become paid next month. The durable skill is being able to switch providers without reinstalling everything.

Verify the setup

Run a real task, not a hello world:

opencode

Then ask it to add a small feature to an existing file. Check three things:

1. It can read the correct file.
2. It proposes a diff before writing.
3. The command it runs is something you understand.

If the model answers but cannot read files, the model is fine and the workspace is wrong. Start OpenCode from the project root.

Common mistakes

• Using an old OpenCode version. Update with npm install -g opencode-ai@latest when a provider stops working.
• Pasting a key with spaces. Copy again and paste into the login prompt, not into a random config file.
• Committing the key. Add .env and local config files to .gitignore.
• Expecting free models to be unlimited. They are not. Build a fallback into your workflow.
• Judging OpenCode after one prompt. Test it on a real task with a model you actually like.

Final thoughts

You now have two ways to run OpenCode for free: a Zen key for a simple setup and OpenRouter for model choice. Install Node, connect both providers, keep two free models ready, and you can code with an agent without a monthly subscription.