Fixed length versus variable length
2026-02-27 · Numeric captchas
Hard-code length only after you have counted real samples from that portal.
Some portals always draw four digits. Some draw a random count. The first group should send length. The second should not.
A wrong length does not produce a helpful error. It produces the best reading of the length you asked for, which will be wrong, and it may still be marked reliable if that wrong string looks clean.
When you add a new portal, save twenty images, count the digits by hand, and only then set the option. Put the count in the same config as the portal name so a later change is obvious.
Batches can override length per item when one queue holds several portals.
Ready to call it? Start with the quickstart, the API guide, or pricing.