Workers KV Instant is a private beta on Quicksilver, with a 1 MB cap

Cloudflare’s 1 October 2026 post introduces Workers KV Instant, a mode of Workers KV backed by Quicksilver, the key-value store Cloudflare has used internally since 2020 and had not offered to customers. The API is the Workers KV API with three stated differences, and the product is a private beta you sign up for. It is aimed at small, rarely updated configuration, not at general storage.

The speed claims, which are Cloudflare’s

Cloudflare says reads are over 100 times faster than classic KV at the high end: under 2 milliseconds even at p99, with p95 “measured in microseconds.” It says 99% of writes replicate in around 250 ms, and that writes reach the edge over 20 times faster than classic mode. Those figures are not accompanied by a method section in the post. Treat them as the vendor’s measurements.

Limits and the three API differences

You opt in by creating the namespace with "mode": "instant". Metadata is unsupported: getWithMetadata returns null, and put does not take metadata. list returns every matching key in one response. There is no pagination. Keys are at most 300 bytes. Values can be any size that keeps the whole namespace at or under 1 MB. A namespace holds at most 10,000 key-value pairs. Writes are limited to one per namespace per second, which Cloudflare contrasts with classic KV’s one write per key per second.

Prices next to classic KV

Cloudflare’s table, in its labels:

	Class B reads	Class A (put, delete, list)	Storage
KV Instant	$0.20 per million	$0.10 per operation	$100 per MB, per month
Workers KV	$0.50 per million	$5.00 per million	$0.50 per GB, per month

A read of three keys is three Class B operations whether you call get three times or once with an array. Each put, delete, or list is one Class A operation, and a list is one operation even though it returns every key. Cloudflare calls the read price 60% lower than classic KV, which matches $0.20 against $0.50. Storage is the other way around: a full 1 MB namespace is $100 a month, against classic KV’s $0.50 per GB. That is why the post tells you to keep Instant for flags and settings, and to leave large or frequently written data on classic KV.

Practical takeaway

Sign up if you need a tiny global config to flip quickly and can live without metadata, pagination, and more than 1 MB. The private beta is not a default for new namespaces. Recheck the Class A price of $0.10 per write before you put Instant on anything that updates often, and remember the one-write-per-namespace-per-second cap.