Workers KV Global Write Propagation Lacks Documented Upper Bound

Direct answer

Cloudflare does not publish a 99th-percentile write propagation latency for Workers KV, nor a replication SLA, maximum delay, or native API for detecting global commit. Writes are acknowledged in the originating data center and replicated asynchronously to other edge locations. Documentation typically describes this as completing within seconds, but that is an observation, not a guarantee.

Confirmed facts

• Workers KV puts are acknowledged locally before asynchronous cross-edge replication.
• Public documentation does not publish a maximum propagation delay, percentile SLA, or programmable global-commit signal.
• expirationTtl does not change replication semantics; key expiration is also eventually consistent.
• Durable Objects provide strong consistency for a single object location, but they do not remove cross-region KV read staleness.
• No published KV binding or API exposes replication lag or a wait-for-propagation primitive.

Likely explanation

Because replication is asynchronous and eventually consistent, staleness windows are unbounded by contract. Network partitions or replication backlogs can extend them beyond typical seconds, and KV has no built-in lag detector. Whether Cloudflare plans to publish an SLA or lag metrics is not publicly confirmed; treat this as unverified and direct to Cloudflare support or your account team.

Verification steps

1. Review the current Cloudflare Workers KV documentation and SLA page for consistency and uptime commitments.
2. Run a controlled write from one edge location and timestamped reads from several others to measure observed propagation. This measures your traffic, not an SLA.
3. Ask Cloudflare support or your account team whether a 99th-percentile target, replication-lag metrics, or commit-detection fields are available or planned.
4. Check the Workers KV API and binding documentation for newly added lag, propagation, or commit-detection fields.

Recommended patterns

Without a native global-commit signal, applications typically use application-level version vectors, read-repair, or external consensus. Durable Objects can coordinate single-location state strongly, but they are not a drop-in replacement for multi-region KV. Synthetic cross-region polling remains the only observable way to detect lag absent a Cloudflare API.

Missing detail

Do you require multi-region strong consistency, or can your design tolerate eventual consistency with conflict resolution? This determines whether Durable Objects, application versioning, or another storage layer is appropriate.