Limits

Your limits depend on your plans and apply to your whole account, across all your keys. Track your usage at any time with GET /v1/usage.

Limits by plan

Live and Historical stack: with both, you get the rights of both. With Live alone, an fc_live_ key has no access to history, not even the Sandbox’s 7 days. A test key always keeps the Sandbox rights. What each plan includes and how to buy it: Plans and billing.

How limits are counted

• Per account: connections, subscriptions, budgets and REST requests per minute are shared by all your keys. Creating more keys does not raise your limits.
• Custom configurations: a WebSocket subscription whose parameters differ from the indicator’s defaults, display parameters included (category: "view" in the catalog). For example, Fathom Trades with a minimum volume (minimum) of 50 instead of 30. Each combination of contract, indicator and parameters counts once, even if several subscriptions use it: live and confirmed count once, and NQ.front counts as the contract it designates (NQ.front and NQZ6 with the same parameters: one configuration). A configuration is released when the last subscription using it closes (unsubscribe or the connection closing; a connection lost without a close is closed by the server after 30 seconds of silence, or released after about 90 seconds at most if our server stops). History queries and exports use none.
• Compute budget: every access to history (a query, an export, or a subscription that starts in the past) consumes compute units: the number of trades in the requested range (trades), multiplied by the indicator’s cost per trade (computeUnitsPerTrade in the catalog, currently 1 for every indicator). The Sandbox’s 50 million compute units cover about 50 to 165 trading days at 1 compute unit per trade. The details are in What drives the cost. Estimate that cost before every query, for free. A live subscription (from: "live") consumes nothing; of a from: {"time": …} subscription, only the part before midnight UTC today is charged, page by page as it is sent.
• Exports: the compute cost of an export’s whole range is charged as soon as it starts, even if you stop reading the response before the end; a resume within 24 hours costs no compute units (see Exports).
• Export volume: the amount of data your exports download, compressed, as you receive it, charged at the end of every response, resumes included.

The compute budget and the export volume renew at the start of every month (UTC), including with the lifetime access of the Historical plan. A request that would exceed them is rejected before it starts, with 429 QUOTA_EXCEEDED.

Technical limits

Unless stated otherwise, these are the same for every plan.

Requests per minute

Your account can send a set number of REST requests per minute, depending on your plan, all keys together. This allowance refills continuously, up to that limit. Every response to a request whose key is recognized carries these headers, a 403 for a missing scope included, as well as a 404 or 405 on an unknown path or method (these requests count toward the limit too). A 401 (missing, invalid, revoked or expired key) belongs to no account and carries none of them, and neither do the public routes, which do not read the key (/v1/indicators, /v1/offers, /v1/pricing):

RateLimit-Limit: 1200
RateLimit-Remaining: 1197
RateLimit-Reset: 1
RateLimit-Policy: 1200;w=60

• RateLimit-Remaining: requests available right now;
• RateLimit-Reset: seconds until the full limit is restored;
• RateLimit-Policy: the limit and its window, in seconds.

Past the limit, the request is rejected with 429 RATE_LIMITED; the Retry-After header says how many seconds to wait. The SDK waits and retries automatically.

Track your usage

curl https://api.fathomcharts.com/v1/usage -H "Authorization: Bearer $FATHOM_CHARTS_API_KEY"

{
  "period": "2026-10",
  "resetsAt": "1793491200000000000",
  "plan": "live_history",
  "limits": {
    "computeBudget": 20000000000,
    "exportBytes": 21474836480,
    "restPerMinute": 1200,
    "historyDays": 36500,
    "delaySeconds": 0,
    "maxConnections": 5,
    "maxSubscriptions": 50,
    "maxCustomConfigs": 25,
    "realtime": true
  },
  "used": { "computeUnits": 1840233, "historyItems": 51207, "exportBytes": 734003200, "restRequests": 412 },
  "remaining": { "computeUnits": 19998159767, "exportBytes": 20740833280 }
}

• plan: your plans, one of sandbox, live, history or live_history (both);
• period and resetsAt: the current month and the date of the next renewal;
• limits: the limits that apply to you. With a test key, these are the Sandbox limits. historyDays is 0 without history (Live plan alone), 7 on the Sandbox, and 36500 for all of our history;
• used and remaining: your usage this month and what you have left. historyItems counts the results your historical queries received, restRequests your REST requests.