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EasyPost vs Shippo vs ShipStation vs ShipEngine: carrier API reliability

Shipzil watches all four shipping platforms in two independent ways: what each one reports about USPS, FedEx and UPS on its own status page, and a real rate request Shipzil sends to each platform's production API every 5 minutes. This page puts both side by side. They answer different questions and are never blended into one score.

Figures as of . Reported window: 90 days from July 9, 2026. Measured: 26 days of checks. This page rebuilds at least daily.

Reported and measured disagree

Shippo has published the most carrier incidents (61), yet answered 100.00% of Shipzil's measured checks. ShipEngine has published 25 and failed 146 of 6,948 measured checks (97.90% success). A platform that publishes more incidents looks worse on reported uptime whether or not it fails more often.

Reported uptime by carrier, 90 days

Calculated by Shipzil from the incidents each platform published, measured from component state changes where the platform gave them. Not independently measured: an outage a platform never reported does not appear. Account-only incidents and standing advisories are excluded.

Carrier EasyPost Shippo ShipStation ShipEngine
USPS 99.50% 5 incidents · 10.7h 94.32% worst 22 incidents · 122.6h 97.50% 4 incidents · 54.1h 99.97% 1 incident · 34m
FedEx 99.81% 3 incidents · 4.1h 95.87% worst 8 incidents · 89.2h 99.53% 3 incidents · 10.2h 99.21% 2 incidents · 17.1h
UPS 99.52% 6 incidents · 10.4h 95.47% 11 incidents · 97.8h 99.53% 3 incidents · 10.2h 94.82% worst 2 incidents · 112.0h

ShipStation and ShipEngine reach USPS through Stamps.com; EasyPost and Shippo connect directly, so their USPS figures describe different integrations. Each carrier page uses the worst platform as its headline, never an average.

Measured rate checks, 26 days

The same domestic US rate request sent to each platform's production API every 5 minutes. A check succeeds when the platform answers within 15 seconds with at least one bookable rate. Slots Shipzil failed to run are not counted for or against anyone.

Platform Check success Failed / checks Median p95 Carriers quoted
EasyPost EasyPost 99.94% 4 / 6,948 1,851ms 4,787ms USPS, FedEx
Shippo Shippo 100.00% 0 / 6,948 1,980ms 4,577ms USPS, UPS
ShipStation Auctane 98.53% 102 / 6,948 3,804ms 10,166ms USPS
ShipEngine Auctane 97.90% 146 / 6,948 4,533ms 12,464ms USPS, UPS

Latency is shown, not ranked. Each monitoring account quotes a different set of carriers, so a faster median is partly a smaller request, and every figure is one lane from one account rather than a platform's overall performance. Methodology · daily rollups (JSON)

Carrier incidents each platform has published

Every carrier-affecting incident in Shipzil's archive, by the platform that filed it. More incidents can mean more outages or simply a more candid status page, which is why this sits beside the measured checks rather than standing in for them.

Of 135 carrier-affecting incidents, 90% were reported by only one company. A carrier problem on one platform alone is usually that platform's integration, not the carrier.

Questions

Which shipping API is the most reliable: EasyPost, Shippo, ShipStation or ShipEngine?
It depends on the carrier and on whether you count what the platforms report or what a real request does. Over the 90 days to October 6, 2026, by each platform's own incident reports, for USPS, ShipEngine had the highest reported uptime (99.97%) and Shippo the lowest (94.32%); for FedEx, EasyPost had the highest reported uptime (99.81%) and Shippo the lowest (95.87%); for UPS, ShipStation had the highest reported uptime (99.53%) and ShipEngine the lowest (94.82%). Measured by Shipzil's own production rate request every 5 minutes over 26 days, the share of checks that returned a bookable rate was EasyPost 99.94% of 6,948, Shippo 100.00% of 6,948, ShipStation 98.53% of 6,948, ShipEngine 97.90% of 6,948. The two measures can disagree: reported uptime only counts outages a platform chose to publish.
EasyPost vs Shippo: which has better uptime?
By the incidents each platform reported over the 90 days to October 6, 2026, EasyPost vs Shippo carrier uptime was USPS 99.50% vs 94.32%, FedEx 99.81% vs 95.87%, UPS 99.52% vs 95.47%. In Shipzil's own measured checks over 26 days, EasyPost returned a bookable rate on 99.94% of 6,948 requests and Shippo on 100.00% of 6,948. Shippo has published more carrier incidents (61 against 40 in Shipzil's archive), and a platform that reports more looks worse on reported uptime, which is why the measured checks are shown beside it.
Are ShipStation and ShipEngine the same platform?
They are separate products from the same company, Auctane. Both reach USPS through Stamps.com rather than directly, and their status pages often publish the same incidents, so Shipzil counts the two as one independent source when deciding whether a carrier problem is corroborated.
How can I tell if a carrier is down or just my shipping platform?
See whether more than one company reports it. A USPS, FedEx or UPS problem reported by only one platform is most likely that platform's integration; reports from two or more independent companies point to the carrier. Of 135 carrier-affecting incidents Shipzil has recorded, 90% were reported by only one company.

Figures as of October 6, 2026. Live status: USPS, FedEx, UPS · Markdown version