Rate Limiting

Simiz uses rate limiting to protect the API, ensure stability, and distribute resources fairly across all customers.

How it works

Flow diagram: incoming requests drain a token bucket with an exhaustion threshold; under the limit returns 200 OK, over the limit returns 429 Too Many Requests with a Retry-After header. — Requests drain a token bucket. While capacity remains the API returns 200; once the burst window is exhausted it returns 429 with a Retry-After header.

Each API key has a daily request limit and a burst rate (max requests per second) based on your plan. Higher plans offer increased limits.

The sandbox environment has relaxed rate limits — test as much as you want during development.

Rate limit headers

Every API response includes headers to help you monitor your usage:

Header	Description
`X-RateLimit-Limit`	Max requests allowed in the time window
`X-RateLimit-Remaining`	Requests remaining in the current window
`X-RateLimit-Reset`	Unix timestamp when the window resets
`Retry-After`	Seconds to wait before retrying (on 429 only)

Handling rate limit errors

When you exceed the limit, the API returns HTTP 429 Too Many Requests:

{
  "error": {
    "code": "rate_limit_exceeded",
    "message": "Rate limit exceeded. Please retry later.",
    "http_status": 429,
    "retry_after": 60
  }
}

Retry with exponential backoff

# Wait and retry with increasing delays
# Attempt 1: wait 1s → Attempt 2: wait 2s → Attempt 3: wait 4s

Best practices

Cache responses

Cache data that doesn’t change often to reduce API calls.

Exponential backoff

On rate limits, wait with increasing delays between retries.

Check headers

Monitor X-RateLimit-Remaining to anticipate limits before hitting them.

Spread calls

Distribute API calls over time instead of sending bursts.

Need higher limits? Contact our sales team for plans with increased rate limits.

Idempotency Pricing

Getting Started

Core Concepts

Billing

Guides

How it works

Rate limit headers

Handling rate limit errors

Retry with exponential backoff

Best practices

Cache responses

Exponential backoff

Check headers

Spread calls

​How it works

​Rate limit headers

​Handling rate limit errors

​Retry with exponential backoff

​Best practices

Cache responses

Exponential backoff

Check headers

Spread calls

How it works

Rate limit headers

Handling rate limit errors

Retry with exponential backoff

Best practices