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Getting started

This guide takes you from a new account to a first model request.

1. Create an account

Sign in at modelrelay.ai with GitHub or Google. New accounts get a one-time signup credit with no card required, so you can make requests right away. Add funds later by card or USDC.

Signing up creates a default project and its first secret API key. Keys begin with mr_sk_.

2. Get an API key

From the dashboard

Open your project in the dashboard and create a key on its API Keys page. Copy it into your environment:

export MODELRELAY_API_KEY=mr_sk_...

From the CLI

Install mrl:

brew install tensor-systems/tap/mrl

Log in, then create a key. mrl keys create prints the key once and saves it as the active profile’s api_key:

mrl auth login --web          # opens a browser on this machine (GitHub by default)
mrl keys create --name laptop

On a server or other machine without a browser, use device sign-in. mrl prints a link; open it on any device, sign in, and approve:

mrl auth login --device

To use the key outside mrl, print it without saving:

export MODELRELAY_API_KEY=$(mrl keys create --name my-app --print)

Never commit API keys to source control. See Authentication for key types and customer tokens.

3. Make a request

curl https://api.modelrelay.ai/v1/chat/completions \
  -H "Authorization: Bearer $MODELRELAY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-5-5",
    "messages": [{"role": "user", "content": "What is the capital of France?"}]
  }'

Or with mrl:

mrl "What is the capital of France?" --model claude-sonnet-5-5

Your first request shows the same request through the native Responses API, the OpenAI SDK, and the Anthropic SDK.

4. Choose a model

Compare models by speed, cost, and intelligence on the models page. Switching models means changing the model string. To list the catalog from the command line:

mrl model list

or call GET /api/v1/models.

Next steps