As of September 23, 2026, USPS API status: 3 operational, 1 impaired across 4 monitored platforms. Last resolved incident: September 22, 2026. Over the last 90 days the worst-performing platform for USPS was Shippo, at 94.83% reported uptime. Shipzil tracks USPS by cross-referencing status reported by EasyPost, Shippo, ShipStation and ShipEngine — four platforms run by three independent companies.
Where a platform published component state changes, the window is measured from those —
when each component actually left and returned to operational. Otherwise it falls back to
when the incident was opened and closed, which overstates it. Either way this is uptime
as reported by the platforms, not independently measured: there may be outages nobody
reported. Account-surface incidents and standing advisories are excluded, since neither
is carrier API downtime.
Of the 127 carrier-affecting incidents behind these figures, 44 (34.6%) had their carriers inferred from the incident title rather than a component the platform tagged. And a platform that reports less looks better here: Shippo 54, EasyPost 39, ShipEngine 25, ShipStation 9 incidents recorded respectively.
Shipzil's own rate checks rather than a platform report: how often a request to each platform returned at least one bookable USPS rate. Only platforms whose monitoring account can quote USPS appear.
A check the platform never answered is excluded from these counts rather than charged to USPS — which is why a platform with unanswered checks shows a smaller total than the rest. Those are the platform's own failures and are listed on its page. Percentages are withheld below 20 checks.
Platform-reported API response time, 24h
Published by the platform about its own API, not measured here and not specific to USPS. Shipzil's own measurement of a USPS rate request through each platform is in Measured reachability above, and is typically several times larger because it includes the carrier call. A platform that stops publishing keeps its last reading for up to two hours before it is dropped, so each row states when it was last published.