Glossary
Vendor Reliability
How consistently a third-party service meets its expected behavior over time.
Definition
Vendor reliability is the measured consistency of a third-party service - uptime, latency distribution and incident frequency - observed independently over stated windows and origin sets.
The problem
Self-reported “99.99% uptime” figures rarely state the window, the origin set, or how outcomes were classified. A number without those is marketing.
Why it matters
Reliability determines architecture (retries, fallbacks, multi-vendor), contract terms (SLA clauses, credits), and incident readiness (who gets paged).
Practical example
Two payment providers both claim four nines. Independent 30-day measurement shows one at 99.98% with a 340ms p95, the other at 99.91% with three multi-region incidents. The architecture decision writes itself.
How RELIASTRA approaches it
RELIASTRA publishes aggregated posture only for vendors made public, always with window and methodology stated. Public Track pages show uptime, latency and incident history measured - not self-reported.
Know when your dependencies fail. Prove what happened.
Monitor the external APIs your product relies on, correlate their failures with your incidents, and generate verifiable evidence when a vendor causes downtime.