diff --git a/packages/graphql/src/auth.test.ts b/packages/graphql/src/auth.test.ts
index 330e6cf..a3e335e 100644
--- a/packages/graphql/src/auth.test.ts
+++ b/packages/graphql/src/auth.test.ts
@@ -92,8 +92,8 @@ const viewerQuery = `
 `;
 
 const revokeSessionMutation = `
-  mutation RevokeSession($session: UUID!) {
-    revokeSession(session: $session) {
+  mutation RevokeSession {
+    revokeSession {
       revoke
     }
   }
@@ -363,7 +363,6 @@ describe("email authentication", () => {
       const revokeResponse = await post(
         {
           query: revokeSessionMutation,
-          variables: { session: session.id },
         },
         authorization,
       );
@@ -382,4 +381,28 @@ describe("email authentication", () => {
       });
     });
   });
+
+  it("not sign in, and reovkes the session", async () => {
+    await withTestHarness(async ({ db, mailer: _, post }) => {
+      await db.insert(schema.accounts).values({
+        id: accountId,
+        email,
+        name: "Sign Out Test",
+      });
+
+      const revokeResponse = await post({
+        query: revokeSessionMutation,
+      });
+      equal(revokeResponse.status, okStatus);
+
+      const responseData = await revokeResponse.json();
+
+      equal(responseData.data, null);
+
+      const error = responseData.errors[0];
+
+      equal(error?.message, "Not authorized to resolve Mutation.revokeSession");
+      equal(error?.path[0], "revokeSession");
+    });
+  });
 });
diff --git a/packages/graphql/src/auth/revoke.ts b/packages/graphql/src/auth/revoke.ts
index bd9a4c8..27e2a59 100644
--- a/packages/graphql/src/auth/revoke.ts
+++ b/packages/graphql/src/auth/revoke.ts
@@ -17,8 +17,7 @@
 // oxlint-disable no-magic-numbers
 
 import { sessions } from "@drfed/models/schema";
-import type { Uuid } from "@drfed/models/uuid";
-import { and, eq } from "drizzle-orm/sql/expressions";
+import { eq } from "drizzle-orm/sql/expressions";
 
 import builder, { type UserContext } from "../builder.ts";
 
@@ -26,16 +25,13 @@ builder.mutationFields((t) => ({
   revokeSession: t.field({
     type: LogoutSuccessRef,
     description: "Revokes a session. Return always `revoke: true`.",
-    args: {
-      session: t.arg({
-        type: "UUID",
-        required: true,
-        description: "The session ID to revoke.",
-      }),
+    authScopes: {
+      authenticated: true,
     },
-    async resolve(_query, { session }, ctx) {
-      if (ctx.session != null) {
-        await deleteSession(session, ctx);
+    async resolve(_query, _, ctx) {
+      const sessionId = ctx.session?.id;
+      if (sessionId) {
+        await deleteSession(ctx);
       }
       // Return always true to prevent brute-force attack.
       return { revoke: true };
@@ -59,9 +55,5 @@ const LogoutSuccessRef = builder
     }),
   });
 
-const deleteSession = (id: Uuid, ctx: UserContext) =>
-  ctx.db
-    .delete(sessions)
-    .where(
-      and(eq(sessions.id, id), eq(sessions.accountId, ctx.session!.accountId)),
-    );
+const deleteSession = (ctx: UserContext) =>
+  ctx.db.delete(sessions).where(eq(sessions.id, ctx.session!.id));
diff --git a/packages/web/.oxlintrc.json b/packages/web/.oxlintrc.json
index 39e48ca..95f0e84 100644
--- a/packages/web/.oxlintrc.json
+++ b/packages/web/.oxlintrc.json
@@ -7,6 +7,7 @@
     "es2022": true
   },
   "rules": {
+    "eslint/require-await": "off",
     "solid/components-return-once": "warn",
     "solid/event-handlers": "warn",
     "solid/imports": "warn",
@@ -29,6 +30,7 @@
     "typescript/explicit-function-return-type": "off",
     "typescript/strict-void-return": "off",
     "typescript/no-non-null-assertion": "off",
+    "typescript/require-await": "off",
     "unicorn/filename-case": "off",
     "unicorn/prefer-query-selector": "off",
     "promise/avoid-new": "off"
diff --git a/packages/web/src/app.tsx b/packages/web/src/app.tsx
index 0dd0bbf..0ce0c5f 100644
--- a/packages/web/src/app.tsx
+++ b/packages/web/src/app.tsx
@@ -17,12 +17,13 @@
 import { MetaProvider, Title } from "@solidjs/meta";
 import { A, Router } from "@solidjs/router";
 import { FileRoutes } from "@solidjs/start/router";
-import { Suspense } from "solid-js";
 
 import "./styles/drfed.css";
 import "./styles/app.css";
+import { Suspense } from "solid-js";
 import { RelayEnvironmentProvider } from "solid-relay";
 
+import { HeaderAccountButton } from "./components/HeaderAccountButton.tsx";
 import { createRelayEnvironment } from "./RelayEnvironment.ts";
 
 import styles from "./styles/app.module.css";
@@ -54,13 +55,7 @@ export default function App() {
                       About
                     </A>
                   </nav>
-                  <A
-                    class={styles.headerAction}
-                    href="/sign-in"
-                    activeClass={styles.active}
-                  >
-                    Sign in
-                  </A>
+                  <HeaderAccountButton />
                 </div>
               </header>
               <div class={styles.content}>
diff --git a/packages/web/src/components/HeaderAccountButton.tsx b/packages/web/src/components/HeaderAccountButton.tsx
new file mode 100644
index 0000000..5637600
--- /dev/null
+++ b/packages/web/src/components/HeaderAccountButton.tsx
@@ -0,0 +1,154 @@
+// DrFed: A web-based platform for developing and debugging ActivityPub apps
+// Copyright (C) 2026 DrFed team
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import { Button } from "@kobalte/core/button";
+import { A, action, useAction, useSubmission } from "@solidjs/router";
+import { commitMutation, graphql } from "relay-runtime";
+import { ErrorBoundary, Show, Suspense } from "solid-js";
+import { createLazyLoadQuery } from "solid-relay";
+
+import { createRelayEnvironment } from "~/RelayEnvironment.ts";
+import { deleteSessionCookie } from "~/session.ts";
+
+import type { HeaderAccountButtonQuery } from "./__generated__/HeaderAccountButtonQuery.graphql.ts";
+import type { RevokeSession } from "./__generated__/RevokeSession.graphql.ts";
+
+import styles from "~/styles/app.module.css";
+
+const revokeSessionMutation = graphql`
+  mutation RevokeSession {
+    revokeSession {
+      revoke
+    }
+  }
+`;
+
+interface revokeSessionResult {
+  message: string;
+  status: "error" | "success";
+}
+
+const signOutAction = action(async () => {
+  "use server";
+
+  const environment = createRelayEnvironment();
+
+  const result = await new Promise<revokeSessionResult>((resolve) => {
+    commitMutation<RevokeSession>(environment, {
+      mutation: revokeSessionMutation,
+      variables: {},
+      onCompleted: (_response, errors) => {
+        const graphQLErrors = errors ?? [];
+
+        if (graphQLErrors.length > 0) {
+          resolve({
+            message: graphQLErrors.map((error) => error.message).join("\n"),
+            status: "error",
+          });
+          return;
+        }
+
+        try {
+          deleteSessionCookie();
+        } catch {
+          resolve({
+            message: "Unable to delete cookie",
+            status: "error",
+          });
+          return;
+        }
+
+        resolve({
+          message: "Signed Out",
+          status: "success",
+        });
+      },
+      onError: (error) => {
+        resolve({
+          message: error.message,
+          status: "error",
+        });
+      },
+    });
+  });
+
+  return result;
+}, "sign-out");
+
+export function HeaderAccountButton() {
+  const signOut = useAction(signOutAction);
+  const submission = useSubmission(signOutAction);
+  const query = createLazyLoadQuery<HeaderAccountButtonQuery>(
+    graphql`
+      query HeaderAccountButtonQuery {
+        viewer {
+          name
+        }
+      }
+    `,
+    {},
+  );
+
+  async function handleSignOut() {
+    const signOutResult = await signOut();
+
+    if (signOutResult.status === "success") {
+      globalThis.location.replace("/");
+    }
+  }
+
+  return (
+    /* A query failure does not mean the viewer is signed out. Instead, it means sever error or network error, making access to other function in this situation will make another error. */
+    <ErrorBoundary fallback={() => <></>}>
+      {/* Avoid auth-state flicker while the viewer query is pending. */}
+      <Suspense fallback={<></>}>
+        <Show when={query()}>
+          {(data) => (
+            <Show
+              when={data().viewer}
+              fallback={
+                <A
+                  class={styles.headerAction}
+                  activeClass={styles.active}
+                  href="/sign-in"
+                >
+                  Sign in
+                </A>
+              }
+            >
+              <Button
+                type="button"
+                class={styles.headerAction}
+                disabled={submission.pending}
+                title={
+                  submission.result?.status === "error"
+                    ? submission.result.message
+                    : "Sign Out"
+                }
+                aria-live="polite"
+                onClick={() => void handleSignOut()}
+              >
+                {submission.result?.status === "error"
+                  ? submission.result.message
+                  : "Sign Out"}
+              </Button>
+            </Show>
+          )}
+        </Show>
+      </Suspense>
+    </ErrorBoundary>
+  );
+}
diff --git a/packages/web/src/session.ts b/packages/web/src/session.ts
index 696fba2..0024f5a 100644
--- a/packages/web/src/session.ts
+++ b/packages/web/src/session.ts
@@ -16,7 +16,11 @@
 
 // oxlint-disable-next-line import/no-unassigned-import -- Environment marker.
 import "server-only";
-import { getRequestProtocol, setCookie } from "@solidjs/start/http";
+import {
+  deleteCookie,
+  getRequestProtocol,
+  setCookie,
+} from "@solidjs/start/http";
 
 const SESSION_COOKIE = "session";
 const ACCESS_TOKEN_PATTERN = /^[A-Za-z0-9_-]{43}$/u;
@@ -48,3 +52,7 @@ export function setSessionCookie(
     secure: getRequestProtocol() === "https",
   });
 }
+
+export function deleteSessionCookie(): void {
+  deleteCookie(SESSION_COOKIE, { path: "/" });
+}