Concepts

Limits and quotas

Daily calls per key, keys per account, one call at a time, the X-Quota-Remaining header and what a 429 means.

LimitTodayWhen you reach it
Calls per day2,000 per key, and 2,000 per connected app429 until 00:00 UTC
Calls at once1 per key or connected app429 until the running call finishes
Active keys3 per accountCreating a fourth fails; revoke one first
Rows per callSet per tool (for example limit up to 100, years up to 20)400 naming the parameter

Calls per dayLink to this section

  • Each key, and each connected app, may make 2,000 successful calls per UTC day. The count resets at 00:00 UTC.
  • REST and MCP calls with the same credential count together.
  • Only successful calls count. A call that fails (a bad parameter, an unknown ticker, a busy key) does not use quota.
  • The limit is per credential, not per account: your keys and connected apps each have their own 2,000.

When the day's calls are used, every call with that credential gets a 429 until midnight UTC:

429 Too Many Requests
{"detail": "This API key has used today's 2000 calls. The quota resets at 00:00 UTC (2026-10-08 00:00 UTC)."}

Over MCP the same sentence comes back as the tool's error text, so the assistant can tell you.

One call at a timeLink to this section

Each key, and each connected app, runs one call at a time. A second call that arrives while the first is still running is refused straight away, without being counted:

429 Too Many Requests
{"detail": "Another call with this API key is still running; the API serves one call at a time per key. Retry when it finishes."}

Make calls one after another. If you do meet this message, wait a moment and retry; the Python and JavaScript quickstarts include a helper that does it. Assistants that call several tools at once get a tool error saying the same thing, and usually retry on their own.

The X-Quota-Remaining headerLink to this section

Every successful REST response carries the calls the credential has left today, after the one just made:

Response header
X-Quota-Remaining: 1987

The header is left out when the daily limit is switched off, or when the count cannot be read at that moment; that never fails the call. MCP responses have no headers you can see, so check usage in your account instead.

Keys per accountLink to this section

An account holds up to 3 active keys. Creating a fourth gives "You already have 3 active API keys. Revoke one to create another." Revoked keys do not count.

Seeing your usageLink to this section

Account → API & MCP shows today's calls against the daily limit, and the last 30 days per day and per key or connected app.

Fair useLink to this section

The quotas are generous for research, notebooks and assistants. They are not meant for copying the dataset: using the API to mirror our data, or spreading calls over extra keys or accounts to get around the limits, is against the Terms. We may change the limits; when a change affects you, we email you first, and it is noted in the API changelog.

Credits are a separate meter that does not block anything today: see Credits.

This page as Markdown, for language models and scripts: /developers/md/concepts/limits