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Rate Limits Overview

Summary

See each API rate limit page for details:

  • REST API Rate Limits

    • Public Endpoints: 10 requests per second, up to 15 requests per second in bursts
    • Private Endpoints: 15 requests per second, up to 30 requests per second in bursts
    • Private /fills endpoint: 10 requests per second, and up to 20 requests per second in bursts
  • FIX API Rate Limits

    • 50 requests per rolling second per session
    • 100 messages per second in bursts
  • Websocket Rate Limits

    • 8 requests every second per IP and up to 20 requests for bursts
    • Messages sent by the client: 100 every second per IP

How Rate Limits Work

Rate-limiting for both the Exchange REST API and the FIX API use a lazy-fill token bucket implementation.

A TokenBucket stores a maximum amount of tokens, which is the burst size, and fills at a given rate called the refresh rate. The bucket starts full, and as requests are received, a token is removed for each request. Tokens are continuously added to the bucket at the refresh rate until full.

When a user sends a request, the TokenBucket calculates whether or not to rate limit the user as follows:

  1. Fill the user's TokenBucket to a token size based on the following formula: token_amount = min(burst, previous_token_amount + (current_time - previous_request_time) * refresh_rate)
  2. Remove 1 token if possible, otherwise rate limit the request.
  3. Repeat Steps 1 and 2 for each subsequent request.

TokenBucket Example

Let's say you have a TokenBucket with burst = 3 and refresh_rate = 1. The table below represents the state of your token bucket after a series of requests:

ActionTimeTokensNotes
Initial State0.03.0New TokenBucket is initialized to max capacity (burst)
Request 10.52.0Fill TokenBucket, then remove a token, because we are at max capacity, and subtract 1 token from 3
Request 20.81.3Fill TokenBucket to 2.3 (min(3, (2 + (.8 - .5) * 1.0)) = min(3, 2.3) = 2.3), then subtract 1
Request 30.90.4Fill TokenBucket to 1.4 (min(3, (1.3 + (.9 - .8) * 1.0)) = min(3, 1.4) = 1.4), then subtract 1
Request 41.00.5Fill TokenBucket to 0.5 (min(3, (.4 + (1.0 - .9) * 1.0)) = min(3, 0.5) = 0.5). Ratelimit because we don't have enough tokens available
Request 51.40.9Fill TokenBucket to 0.9 (min(3, (0.5 + (1.4 - 1.0) * 1.0)) = min(3, 0.9) = 0.9). Ratelimit because we don't have enough tokens available
Request 61.80.3Fill TokenBucket to 1.3 (min(3, (0.9 + (1.8 - 1.4) * 1.0)) = min(3, 1.3) = 1.3), then remove 1
Request 75.02.0Fill TokenBucket to 3.0 (min(3, (0.3 + (5.0 - 1.8) * 1.0)) = min(3, 3.5) = 3), since we would "overflow" with our calculations, then subtract 1