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Quicksilver

Quicksilver is Cloudflare's internally-developed, globally-distributed key-value store built for "incredibly fast global replication and low-latency access" at planet scale. It is the configuration- distribution backbone of Cloudflare's network: "nearly every request to Cloudflare looks up at least one key in Quicksilver" (Source: sources/2026-10-01-cloudflare-introducing-workers-kv-instant-powered-by-quicksilver). Introduced in 2020 and evolved through Quicksilver v2, it was for years an internal-only system — "people have asked us for years, but we've never made Quicksilver available to our customers" — until 2026-10-01, when Cloudflare exposed it to customers as the engine behind Workers KV Instant.

Role

  • Edge configuration distribution — push a small key globally and have it readable with near-zero latency on every request at every POP. This is the workload Cloudflare runs on it internally (rules, settings, routing config).
  • Hot-path read tier (concepts/hot-path) — optimized for the read-on-every-request pattern, not for bulk storage.
  • Globally-replicated writes from a single system of record — writes go through one authoritative writer and fan out to 300+ edge locations (leader/follower), giving fast, strictly-ordered, instantly-visible updates.

Design shape (as disclosed via KV Instant)

The KV Instant launch does not re-derive Quicksilver's internals (it links the dedicated Quicksilver v2 series), but the exposed performance envelope characterizes it:

  • Read latency — p99 1.62 ms to all reads (p95 in microseconds) — ~100× faster than classic Workers KV's cached-read path.
  • Write replication — median 107 ms, p95 181 ms, p99 256 ms to replicate to all 300+ edge locations.
  • Single system of record for writes — the write path funnels through one authoritative writer; this is what buys instant global visibility (no TTL) and strictly-ordered updates, and is also why KV Instant imposes a one-write-per-namespace-per-second ceiling.
  • Small-value / small-dataset bias — the KV Instant exposure caps a namespace at 1 MB / 10,000 keys, 300-byte keys — matching Quicksilver's config-distribution origin (many tiny, read-hot values) rather than general-purpose storage.

Quicksilver v2

Quicksilver v2 is the current generation and the specific engine behind KV Instant: "KV Instant is powered by Quicksilver v2, a key-value store developed internally by Cloudflare to enable fast global replication and low-latency access on a planet scale." The v2 evolution is documented in Cloudflare's multi-part Quicksilver v2 series.

Relationship to Workers KV

Workers KV and Quicksilver are two different engines for two different data/access patterns, now unified under one API via KV Instant mode:

  • Classic Workers KV — eventually-consistent (concepts/eventual-consistency), edge-cached, TTL-bounded staleness; good for larger values written occasionally, read frequently.
  • KV Instant (Quicksilver) — ~1.6 ms p99 reads, ~250 ms p99 global write replication, no TTL; good for small, infrequently-updated, read-on-every-request config (latency-critical).

See Workers KV for the full mode comparison and cost model.

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