diff --git a/.changeset/soft-spiders-care.md b/.changeset/soft-spiders-care.md
new file mode 100644
index 00000000..600e13e7
--- /dev/null
+++ b/.changeset/soft-spiders-care.md
@@ -0,0 +1,5 @@
+---
+"@effect-atom/atom": minor
+---
+
+allow overriding AtomHttpApi & AtomRpc runtime factory
diff --git a/docs/atom/AtomHttpApi.ts.md b/docs/atom/AtomHttpApi.ts.md
index 0c04b3c6..3e73e47c 100644
--- a/docs/atom/AtomHttpApi.ts.md
+++ b/docs/atom/AtomHttpApi.ts.md
@@ -49,6 +49,7 @@ export declare const Tag: <Self>() => <
       | ((effect: Effect.Effect<unknown, unknown>) => Effect.Effect<unknown, unknown>)
       | undefined
     readonly baseUrl?: URL | string | undefined
+    readonly runtime?: Atom.RuntimeFactory | undefined
   }
 ) => AtomHttpApiClient<Self, Id, Groups, ApiE, E>
 ```
diff --git a/docs/atom/AtomRpc.ts.md b/docs/atom/AtomRpc.ts.md
index 06d654ed..375540c3 100644
--- a/docs/atom/AtomRpc.ts.md
+++ b/docs/atom/AtomRpc.ts.md
@@ -41,6 +41,7 @@ export declare const Tag: <Self>() => <
     readonly generateRequestId?: (() => RequestId) | undefined
     readonly disableTracing?: boolean | undefined
     readonly makeEffect?: Effect.Effect<RpcClient.RpcClient.Flat<Rpcs, RpcClientError>, never, RM> | undefined
+    readonly runtime?: Atom.RuntimeFactory | undefined
   }
 ) => AtomRpcClient<Self, Id, Rpcs, ER>
 ```
diff --git a/packages/atom/src/AtomHttpApi.ts b/packages/atom/src/AtomHttpApi.ts
index a58f1d05..cb622d92 100644
--- a/packages/atom/src/AtomHttpApi.ts
+++ b/packages/atom/src/AtomHttpApi.ts
@@ -161,6 +161,7 @@ export const Tag =
         | ((effect: Effect.Effect<unknown, unknown>) => Effect.Effect<unknown, unknown>)
         | undefined
       readonly baseUrl?: URL | string | undefined
+      readonly runtime?: Atom.RuntimeFactory | undefined
     }
   ): AtomHttpApiClient<Self, Id, Groups, ApiE, E> => {
     const self: Mutable<AtomHttpApiClient<Self, Id, Groups, ApiE, E>> = Context.Tag(id)<
@@ -172,7 +173,8 @@ export const Tag =
       self,
       HttpApiClient.make(options.api, options)
     ).pipe(Layer.provide(options.httpClient)) as Layer.Layer<Self, E>
-    self.runtime = Atom.runtime(self.layer)
+    const runtimeFactory = options.runtime ?? Atom.runtime
+    self.runtime = runtimeFactory(self.layer)
 
     const mutationFamily = Atom.family(({ endpoint, group, withResponse }: MutationKey) =>
       self.runtime.fn<{
diff --git a/packages/atom/src/AtomRpc.ts b/packages/atom/src/AtomRpc.ts
index 91c2ad98..bbec106e 100644
--- a/packages/atom/src/AtomRpc.ts
+++ b/packages/atom/src/AtomRpc.ts
@@ -118,6 +118,7 @@ export const Tag = <Self>() =>
     readonly generateRequestId?: (() => RequestId) | undefined
     readonly disableTracing?: boolean | undefined
     readonly makeEffect?: Effect.Effect<RpcClient.RpcClient.Flat<Rpcs, RpcClientError>, never, RM> | undefined
+    readonly runtime?: Atom.RuntimeFactory | undefined
   }
 ): AtomRpcClient<Self, Id, Rpcs, ER> => {
   const self: Mutable<AtomRpcClient<Self, Id, Rpcs, ER>> = Context.Tag(id)<
@@ -133,7 +134,8 @@ export const Tag = <Self>() =>
         flatten: true
       }) as Effect.Effect<RpcClient.RpcClient.Flat<Rpcs, RpcClientError>, never, RM>
   ).pipe(Layer.provide(options.protocol))
-  self.runtime = Atom.runtime(self.layer)
+  const runtimeFactory = options.runtime ?? Atom.runtime
+  self.runtime = runtimeFactory(self.layer)
 
   self.mutation = Atom.family(<Tag extends Rpc.Tag<Rpcs>>(tag: Tag) =>
     self.runtime.fn<{