CAPTCHA Timeouts

Two clocks run around a challenge, and both are configurable per site.

Setting	What it bounds	Default
Solution timeout	From the challenge being issued to the user submitting an answer	60 seconds
Verified timeout	From the user solving to your server calling verify	120 seconds

Both accept 1 to 600 seconds.

Solution timeout

Section titled Solution timeout

How long the user has to solve the challenge in front of them. A solution submitted after this window is rejected as stale and the user gets a fresh challenge.

Raise it if your challenge sits on a page where people are legitimately slow — a long form they fill in around the widget, or an accessibility need. Lower it and you shorten the window in which a challenge can be farmed out to a solving service, at the cost of failing genuine slow users.

Verified timeout

Section titled Verified timeout

How long your server has, after the user solves, to call server-side verification with the token. Past this window the token is no longer verifiable and your call returns unverified.

This is the one to think about if your form does work between the user’s click and your verify call — a slow upload, a payment step, a queue. The window has to cover your worst case, not your median. Shorter windows reduce the time a leaked or shared token is worth anything to someone who intercepts it.

Caution

The verified timeout is the one that fails silently in production. It is measured against your server’s clock reaching Prosopo, so it has to cover your slowest path — retries, cold starts, a queued job between submit and verify — not your average one. Set below that and the symptom is genuine users failing verification with a valid token.

Where to set them

Section titled Where to set them

The Captcha Timeouts card is on the General Settings tab of Site Settings. Changes apply to new sessions on that site key; nothing needs redeploying.