Setting up Synthetic with OpenClaw

I used to spend way too much time tweaking API calls every time I wanted to try a new model. It felt like I was writing boilerplate instead of building features. I wanted a way to use different models without rewriting my entire integration.

Then I found Synthetic. It maps everything to the Anthropic Messages API, which is exactly what OpenClaw likes. It makes switching between models like MiniMax or DeepSeek feel like a simple configuration change instead of a major project.

What You’ll Need

• An active SYNTHETIC_API_KEY.
• OpenClaw installed on your machine.

Quick Start

You can get this running in about five minutes. I recommend using the onboarding wizard because it handles the heavy lifting for you.

1. Set your API key: Export your key to your environment so OpenClaw can find it.

   export SYNTHETIC_API_KEY="your-sk-here"

2. Run the onboarding: This command registers the provider and sets up your initial config.

   openclaw onboard --auth-choice synthetic-api-key

The default model is synthetic/hf:MiniMaxAI/MiniMax-M2.1. If you want to customize your setup, here is what your config.json5 should look like:

{
  env: { SYNTHETIC_API_KEY: "sk-..." },
  agents: {
    defaults: {
      model: { primary: "synthetic/hf:MiniMaxAI/MiniMax-M2.1" },
      models: { "synthetic/hf:MiniMaxAI/MiniMax-M2.1": { alias: "MiniMax M2.1" } },
    },
  },
  models: {
    mode: "merge",
    providers: {
      synthetic: {
        baseUrl: "https://api.synthetic.new/anthropic",
        apiKey: "${SYNTHETIC_API_KEY}",
        api: "anthropic-messages",
        models: [
          {
            id: "hf:MiniMaxAI/MiniMax-M2.1",
            name: "MiniMax M2.1",
            reasoning: false,
            input: ["text"],
            cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
            contextWindow: 192000,
            maxTokens: 65536,
          },
        ],
      },
    },
  },
}

Troubleshooting

Even simple setups have quirks. Here are two things that usually trip people up:

• The URL Suffix: OpenClaw’s Anthropic client adds /v1 to the end of the base URL automatically. Make sure your baseUrl is https://api.synthetic.new/anthropic. If you add /v1 yourself, the final URL will be broken and calls will fail.
• Missing Models: If you use an allowlist in agents.defaults.models, you have to manually add every model ID you want to use. If a model isn’t in that list, OpenClaw will block the request.
• Incorrect Prefixes: Always use the synthetic/ prefix when referencing models in your agent settings.
• Authentication Errors: Double-check that your SYNTHETIC_API_KEY is actually loaded in your current shell session.

If you hit a wall, you can always ask the AI Setup Assistant for help.

What’s Next

• Model providers
• Configuring Agents