Two workers must not solve one image twice
2026-01-30 · Captchas
Decide who owns the image before you call the API, or you will pay twice for one answer.
A queue that hands the same PNG to two workers gets two identical readings and two charges when both are reliable. Deduplicate on a hash of the bytes before you call.
The API does not do that for you. It treats every request as new. Credits are reserved up front with one conditional update, then the unreliable part is refunded. Two requests reserve two credits.
The per-key cap is 32 synchronous calls in flight and 256 unfinished submitted tasks. A retry storm hits 429 too_many_concurrent_requests and comes with Retry-After.
One owner per image keeps you under that cap and keeps the bill equal to the number of captchas you actually had.
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