Create an Opper account

Sign up needs no credit card: you get an API key straight away and the free models work in the playground and the API. Add a card to use premium models, pay-as-you-go with no minimum.

Create account

What happens next

  1. Create your account at platform.opper.ai. No card is asked for.
  2. Get your API key. It is under Settings → API keys in the dashboard, or the CLI prints one after npx @opperai/cli login && npx @opperai/cli config get default.
  3. Make your first call with the OpenAI SDK against https://api.opper.ai/v3/compat, or with the curl below.

Using a coding agent? Connect it to the MCP server at https://api.opper.ai/mcp and it can create the project and the API key for you, once you approve it in the browser. See https://opper.ai/mcp.

Your first call

curl https://api.opper.ai/v3/compat/chat/completions \
  -H "Authorization: Bearer $OPPER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"gemini/gemma-4-31b","messages":[{"role":"user","content":"Say hello in one sentence."}]}'

gemini/gemma-4-31b is a free model, so this call works before you add a card. It runs on a US-hosted route. The premium models on EU-hosted routes need a card on file; they are listed at https://opper.ai/models/eu.

Before you add a card

  • Free models work in the playground and through the /v3 API, with no time limit.
  • A premium model returns HTTP 402 with the error type plan_required until a card is on file.
  • Embeddings, realtime sessions and image generation need a card on file.

Browse every model at opper.ai/models; pricing is at opper.ai/pricing.