Memory

In-process caching over IMemoryCache. Included in the ActionCache package — no extra install.

builder.Services.AddActionCache(options =>
{
    options.UseMemoryCache(memory => memory.SizeLimit = 10_000);
});

The delegate configures MemoryCacheOptions directly, so anything that type supports is available here.

Set a size limit

Nothing bounds an in-memory cache by default. With per-user keys on by default, an authenticated endpoint holds one entry per user, so an unbounded cache grows with your user count:

options.UseMemoryCache(memory => memory.SizeLimit = 10_000);

When to use it

• A single instance, where a shared store buys nothing.
• As the first layer of a chain, in front of Redis or SQL Server — a hit in the deeper layer is promoted into this one, so the round-trip is paid once. See Layered backends.

What it does not do

Entries are per process. With several instances running, each has its own cache, and an eviction on one does not reach the others — use a shared backend when that matters.

UseDistributedSingleFlight() cannot be backed by this backend; it needs Redis or SQL Server.