Rate Limits

BlockRun is a pass-through gateway: for paid model calls it does not add its own per-request throttle. The rate limits you may hit are the upstream provider's capacity limits (tokens-per-minute / requests-per-minute on the provider tier backing that model). When an upstream provider throttles a request, BlockRun surfaces it to you transparently as an HTTP 429 so you can back off or fail over.

No platform throttle on paid calls

For paid model calls there is no BlockRun-side per-request limit — your only ceiling is the upstream provider's TPM/RPM. Some non-LLM endpoints (image generation, async job submission, wallet reconciliation, RealFace init) carry small per-IP limits to bound abuse and real upstream cost.

The `429` response

When an upstream provider rate-limits a request, BlockRun returns:

HTTP/1.1 429 Too Many Requests
Retry-After: 60
X-RateLimit-Source: anthropic
Content-Type: application/json

{
  "error": "Rate limited",
  "message": "Upstream provider rate limit hit — retry after 60s, or fail over to a same-tier model on a different provider.",
  "code": "RATE_LIMITED",
  "source": "anthropic",
  "retry_after_seconds": 60
}

Field / Header	Meaning
`Retry-After` (header)	Seconds to wait before retrying. Honor this.
`X-RateLimit-Source` (header)	Which upstream provider throttled (`anthropic`, `openai`, …).
`code`	Always `RATE_LIMITED` for this case.
`retry_after_seconds`	Same value as `Retry-After`, in the body for convenience.

This applies to both the standard (POST /api/v1/chat/completions) and Anthropic-compatible (POST /api/v1/messages) endpoints, for streaming and non-streaming requests. For streaming, the 429 is returned before the first SSE byte (no partial stream is emitted).

Recommended client handling

Honor Retry-After — wait the indicated seconds, then retry (exponential backoff on repeats).
Or fail over to a same-tier model on a different provider — e.g. if anthropic/claude-sonnet-4.6 is throttled, retry on openai/gpt-5.4 or google/gemini-3-pro-preview. Different providers have independent rate-limit pools, so a cross-provider retry usually succeeds immediately.

import time
resp = client.chat(...)
if resp.status_code == 429:
    time.sleep(int(resp.headers.get("Retry-After", 60)))
    resp = client.chat(...)            # retry
    # or: client.chat(model="openai/gpt-5.4", ...)  # cross-provider failover

Provider notes

Claude (anthropic/*) is served through AWS Bedrock (cross-region inference) with a fallback to the direct Anthropic API. A 429 here means both pools were saturated; back off or fail over to another provider.
GPT (openai/*) mainline chat models are served Azure-first with a fallback to direct OpenAI.

In both cases the failover is automatic and internal — you only see a 429 when every backing pool for that model is exhausted.

Other endpoints

Some non-LLM endpoints (image generation, async job submission, wallet reconciliation, RealFace init) carry small per-IP limits to bound abuse and real upstream cost. When exceeded they also return 429; the same Retry-After guidance applies.

What's next?

Chat Completions

The paid LLM endpoint where upstream provider limits apply.

Models

The model catalog and which provider backs each one.

x402 Endpoints