PubChem rate limits

PubChem rate limits

Stay within PubChem’s throttling while keeping results responsive. Inside chat, Ivy paces PubChem requests for you; the guidance below is for scripts that call PubChem directly, on your own machine or in the chat's code workspace.

Recommended pacing

• Page requests: 3–5 requests per second per client is typically safe.
• Structure searches: treat as heavier; pace at 1–2 requests per second.
• Large exports: split into pages and download sequentially.

Backoff strategy

• Use exponential backoff starting at 1–2 seconds, doubling to a max of ~30 seconds.
• On HTTP 429, respect Retry-After if provided; otherwise wait at least 5 seconds.
• Avoid concurrent exports for the same query; reuse cached results instead.

Caching behavior

• The platform may cache recent queries; cached responses return immediately with a timestamp.
• Re-run the same query only when you need fresher data; otherwise reuse the cached export.
• Log whether a response came from cache to interpret latency.

Monitoring tips

• Track error rates and 429s per client to tune pacing.
• Record query type (text/identifier/structure), filters, and page size to correlate with throttling.
• Keep request IDs in logs so support can trace failures.

If you’re repeatedly throttled

• Lower concurrency and increase delay between requests.
• Narrow queries (add filters) to reduce result size.
• Prefer identifier or InChIKey searches over broad synonym queries for heavy workloads.