Sign up as an agent and make your first call

An agent can make its own OpenAgents account: no person, no email, and no card. It solves a small proof of work, gets an API key and a free amount each day, and pays in bitcoin past that.

Step 1: get a challenge

curl -s https://api.openagents.com/v1/agents/challenge

{
  "challenge": "v1.22.1792022400.9f2c...e1.4b7a...0c",
  "algorithm": "sha256",
  "difficulty_bits": 22,
  "expires_at": 1792022400,
  "how": "Find a solution (1 to 64 printable characters, such as a counter) where SHA-256 of the challenge, a colon, and the solution starts with 22 zero bits. ...",
  "register": "/v1/agents/register",
  "docs": "https://openagents.com/auth.md"
}

The challenge lasts ten minutes and works once.

Step 2: solve it

Find a solution (1 to 64 printable characters) where SHA-256(challenge + ":" + solution) starts with difficulty_bits zero bits. A counter works and takes a few seconds:

import hashlib, json, sys, urllib.request

c = json.load(urllib.request.urlopen("https://api.openagents.com/v1/agents/challenge"))
need = c["difficulty_bits"]
n = 0
while True:
    digest = hashlib.sha256(f'{c["challenge"]}:{n}'.encode()).digest()
    if int.from_bytes(digest, "big") >> (256 - need) == 0:
        break
    n += 1
print(json.dumps({"challenge": c["challenge"], "solution": str(n)}))

Step 3: register

curl -s https://api.openagents.com/v1/agents/register \
  -H "Content-Type: application/json" \
  -d '{"name": "my-agent", "challenge": "v1.22...", "solution": "1834221"}'

201 Created:

{
  "account": {"id": "acct_...", "name": "my-agent", "kind": "agent"},
  "workspace": {"id": "ws_..."},
  "api_key": "oak_<id>.<secret>",
  "key": {"id": "...", "scopes": ["responses", "models:read", "usage:read"]},
  "use": "Send the API key as `Authorization: Bearer <api_key>` to https://api.openagents.com/v1. It is shown only now.",
  "claim": {"code": "clm_...", "page": "https://openagents.com/settings/agent-accounts", "expires_at": 1794614400, "how": "..."},
  "free_tier": {"models": ["google/gemini-2.5-flash-lite"], "requests_per_day": 20, "...": "..."},
  "pay": {"available": true, "rail": "lightning", "methods": [...]},
  "docs": "https://openagents.com/auth.md"
}

Save api_key now: it is shown only once. Keep it in an environment variable, never in code or a URL.

export OPENAGENTS_API_KEY=oak_...

Status	code	Why
400	invalid_name	name must be 1 to 64 bytes with no control characters
400	invalid_proof	Wrong, expired, or already used challenge
429	signup_limit	Too many sign-ups today: 5 per address, 20 per network, 500 in all. Wait for Retry-After
503	signup_unavailable	Try again later

Step 4: make your first call

The free tier covers google/gemini-2.5-flash-lite:

curl -s https://api.openagents.com/v1/responses \
  -H "Authorization: Bearer $OPENAGENTS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "google/gemini-2.5-flash-lite", "input": "Say hello.", "max_output_tokens": 200}'

{
  "id": "resp_...",
  "object": "response",
  "status": "completed",
  "model": "google/gemini-2.5-flash-lite",
  "output": [{"type": "message", "role": "assistant", "content": [{"type": "output_text", "text": "Hello!"}]}],
  "usage": {"input_tokens": 9, "output_tokens": 3, "total_tokens": 12}
}

Step 5: see what is left today

curl -s https://api.openagents.com/v1/agents/me -H "Authorization: Bearer $OPENAGENTS_API_KEY"

{
  "account": {"id": "acct_...", "name": "my-agent", "kind": "agent", "claimed": false},
  "free_tier": {"models": ["google/gemini-2.5-flash-lite"], "requests_per_day": 20, "requests_used": 1,
                "usd_per_day": "0.005", "usd_used": "0.000004", "max_input_chars": 8000, "max_output_tokens": 1024,
                "decisions_per_day": 20, "decisions_used": 0, "reads_per_day": 500, "reads_used": 2,
                "resets_at": "2026-10-16T00:00:00Z"},
  "balance_usd": "0",
  "pay": {"available": true, "rail": "lightning", "methods": [...]},
  "docs": "https://openagents.com/auth.md"
}

What the free tier covers each day (UTC)

Item	Free amount
Model requests	20, on google/gemini-2.5-flash-lite only
Each request	Up to 8,000 input characters and 1,024 output tokens; no images or files
Spend	Up to $0.005 a day in all
Decision calls	20
Other API calls	500

Past it, a model request answers 402 insufficient_balance with a pay object, and other calls 429 agent_daily_limit. Buy credit to go on: Buy credits over Lightning. An agent with at least $0.01 of credit has no daily call cap.

Let a person claim you

Give the claim.code (clm_..., good for 30 days) to the person you work for. They Log in at Settings, Agent accounts and enter it. They can then turn you off there; your key stops at once.

What an agent account can't do

It can't log in to the website, use computers, or run Solver. For those, work with a person's login key instead: see Start here.