A DeepSeek V4.1 Flash OpenCode setup is one of the easiest ways to get a strong AI coding agent for free right now. OpenCode Zen lists a free DeepSeek V4.1 Flash model for a limited time, so you can start without an API key. In the video below I set it up and build with it. This guide gives you the install commands, the free and paid routes, and how to use Plan, Build and subagents.
Key takeaways
- OpenCode Zen has a free deepseek-v4.1-flash-free model for a limited time.
- Install with one command, then pick the model with
/models. - Or use your own DeepSeek key via
/connect. - Use Plan first, then Build. Claim a free strategy session for help.
Why DeepSeek V4.1 Flash and OpenCode?
OpenCode is an open-source coding agent that runs in your terminal. It reads your project, makes changes and runs commands. DeepSeek V4.1 Flash is a fast, cheap model with strong coding scores: after the 17 October update it hits 77.0 on DeepSWE, per its model card.
Put them together and you get a capable coding agent that costs nothing while the free offer lasts. If you want the model details — architecture, pricing and benchmarks — read my DeepSeek V4.1 Flash guide. This page is the hands-on setup.
Step 1: Install OpenCode
Pick one of these, from the OpenCode docs:
curl -fsSL https://opencode.ai/install | bash
# or with npm
npm install -g opencode-ai
# or with Homebrew
brew install anomalyco/tap/opencodeBe careful with Homebrew: brew install opencode installs OpenCode 2, which is a different package. Use the tap command above. Then open your project folder and run:
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Step 2: Pick the free DeepSeek model
OpenCode Zen is OpenCode’s own set of hosted models. The Zen docs list deepseek-v4.1-flash-free as “Free for a limited time”.
- Type
/modelsinside OpenCode. - Choose DeepSeek V4.1 Flash Free.
- Zen model IDs look like
opencode/<model-id>if you set it in config.
Zen says the free model uses zero data retention and isn’t used for training. Free chat models only work inside OpenCode. If you don’t want to see free models at all, set OPENCODE_DISABLE_FREE_MODELS=1.
Free offers end. When this one does, switch to the paid Zen model or your own DeepSeek key below.
Step 3 (optional): Use your own DeepSeek key
Want more control or higher limits? Connect DeepSeek directly, as the providers page explains:
- Type
/connectin OpenCode. - Choose DeepSeek and paste your API key.
- Run
/modelsand pick the DeepSeek model.
OpenCode saves your key in ~/.local/share/opencode/auth.json. Run opencode auth list to see which providers you’ve connected.
| Route | Cost per million tokens | Notes |
|---|---|---|
| Zen free | $0 | Limited time, inside OpenCode only |
| Zen paid deepseek-v4.1-flash | $0.30 in / $1.20 out | Billed through OpenCode Zen |
| Your own DeepSeek key | $0.30 / $1.20 peak, half off-peak | Billed by DeepSeek |
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Step 4: Set up your project with /init
Run /init the first time you open a project. OpenCode reads your code and writes an AGENTS.md file. That file tells the agent how your project is laid out, how to run it and what rules to follow. Commit it so every session starts with the same context.
Use @ to find and attach files to your message, and /undo or /redo if a change goes wrong.
Step 5: Plan first, then Build
OpenCode has two main modes. Press Tab to switch between them.
| Mode | What it does | When to use it |
|---|---|---|
| Plan | Thinks through the job without editing files | Start every bigger task here |
| Build | Edits files and runs commands | Once you’re happy with the plan |
This is the habit that saves the most time. Ask for a plan, read it, fix anything that’s wrong, then switch to Build. DeepSeek V4.1 Flash is fast, so this loop feels quick.
Step 6: Use subagents for bigger jobs
OpenCode comes with two subagents, General and Explore. Mention one with @general to hand it a side task, like searching the codebase, while your main agent keeps working. Per the agents docs, subagents use the same model as the agent that called them, so they’ll run on DeepSeek too.
You can also make your own agents:
opencode agent create
opencode agent listCustom agents live in .opencode/agents/ in your project or ~/.config/opencode/agents/ for all projects. Each one has a short header with its description, mode, model and permissions.
Want the short version? I also wrote a quick-start version of this setup on the AI Profit Boardroom blog.
What to build first
- A small landing page from a one-paragraph brief.
- A script that tidies a messy folder of files.
- Tests for an existing function you don’t trust.
- A bug fix, with Plan mode explaining the cause first.
Start small, check the output, then give it bigger jobs. Always review changes before you push them.
Common problems and fixes
| Problem | Fix |
|---|---|
| Free model not showing | Check OPENCODE_DISABLE_FREE_MODELS isn’t set, then run /models again |
| Homebrew installed the wrong app | Uninstall it and use brew install anomalyco/tap/opencode |
| Agent ignores your project rules | Run /init again and add your rules to AGENTS.md |
| A change broke something | Type /undo, then ask for a plan in Plan mode |
| Rate limits on the free model | Connect your own DeepSeek key with /connect |
Most problems come down to the model picker or a missing AGENTS.md. Fix those two and the rest is usually smooth.
One more tip: keep AGENTS.md short and specific. List how to run the project, how to run tests and any rules the agent must follow, like files it should never touch. A clear AGENTS.md makes a cheap model like DeepSeek V4.1 Flash behave much more like an expensive one.
My verdict on DeepSeek V4.1 Flash in OpenCode
A DeepSeek V4.1 Flash OpenCode setup is the best free coding stack I’ve tried this month. Install takes one command, the free Zen model needs no key, and Plan, Build and subagents make it easy to use well. Try DeepSeek V4.1 Flash in OpenCode while the free offer lasts.
About Julian Goldie
I’m Julian Goldie — founder of Goldie Agency and the AI Profit Boardroom. I test new AI agents almost every day for 432K+ YouTube subscribers and run Hermes, OpenClaw, OpenCode, Claude and Codex side by side in my own Agent OS. Claim your free strategy session or join the AI Profit Boardroom.
FAQ: deepseek v4.1 flash opencode
Is DeepSeek V4.1 Flash free in OpenCode?
Yes, for a limited time. OpenCode Zen lists deepseek-v4.1-flash-free, which you can pick with /models.
How do I install OpenCode?
Run curl -fsSL https://opencode.ai/install | bash, or npm install -g opencode-ai, or brew install anomalyco/tap/opencode.
How do I add my own DeepSeek API key to OpenCode?
Type /connect, choose DeepSeek, paste your key, then pick the model with /models.
What does /init do in OpenCode?
It reads your project and creates an AGENTS.md file with instructions for the agent.
Is my code used for training on the free model?
OpenCode Zen says the free model uses zero data retention and isn’t used for training.
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Related reading
Last updated October 2026. This page is a living guide to deepseek v4.1 flash opencode — the facts here move fast and it is updated as they do.
