diff --git a/CHANGELOG.md b/CHANGELOG.md
index 270d3e2..df32e36 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- The commit menu, on a row or a graph node, copies the full commit id and,
+  when the origin is on github.com or gitlab.com, copies or opens the
+  commit's web page
+  ([#15](https://github.com/ShortArrow/gitreant/issues/15)).
+
 ### Changed
 
 - "Diff all" is a toggle: pressed while every file's diff is open, it closes
diff --git a/docs/FEATURES.jp.md b/docs/FEATURES.jp.md
index e61b051..8b47099 100644
--- a/docs/FEATURES.jp.md
+++ b/docs/FEATURES.jp.md
@@ -17,7 +17,7 @@ gitreant でできることを分野別にまとめる。起動方法とコマ
 
 - **レーンと色はサーバで計算する。** チェックアウト中のブランチを左端の直線に置き、分岐は右へ、マージは右から合流する。ブランチの線は端から端まで同じ色で描く。
 - **HEAD とマージ。** HEAD のコミットは中抜きの輪で描く。マージコミットのメッセージは薄く表示する。
-- **ノードの操作。** ノードにホバーするとハッシュを表示し、クリックでそのコミットを選ぶ。右クリックでコミット行と同じメニュー（タグやブランチの作成）を開く。ハッシュのクリックでフル ID をコピーする。
+- **ノードの操作。** ノードにホバーするとハッシュを表示し、クリックでそのコミットを選ぶ。右クリックでコミット行と同じメニューを開き、フル ID のコピー、タグやブランチの作成ができる。origin が github.com か gitlab.com にあれば、コミットの Web ページの URL をコピーしたり、そのページを開いたりもできる。ハッシュのクリックでフル ID をコピーする。
 - **バッジ。** ブランチ・タグ・stash を別々のバッジで描く。リモートのブランチやリモートに push 済みのタグには、リモート名の区切りを付ける。
 - **stash。** stash は 1 つのノードにたたんで描く。設定で、index と未追跡ファイルの内部コミットを点線で開いて見せられる。
 - **サブモジュールのグラフ。** サブモジュールを持つリポジトリでは、サブモジュールのグラフを左側に並べ、サブモジュールのポインタを動かしたコミットどうしを点線で結ぶ。設定で切り替えられる。
diff --git a/docs/FEATURES.md b/docs/FEATURES.md
index 4de1205..f810e6a 100644
--- a/docs/FEATURES.md
+++ b/docs/FEATURES.md
@@ -36,8 +36,9 @@ see the [README](../README.md); design decisions live in [adr/](adr/).
 - **HEAD and merges.** The HEAD commit is a hollow ring; merge commit
   messages are dimmed.
 - **Nodes.** Hovering a node shows its hash and clicking selects the
-  commit. Its context menu is the commit row's (create a tag or a branch).
-  Clicking a hash copies the full id.
+  commit. Its context menu is the commit row's: copy the full id, create a
+  tag or a branch, and, when the origin is on github.com or gitlab.com, copy
+  or open the commit's web page. Clicking a hash copies the full id.
 - **Badges.** Branches, tags and the stash render as distinct badges. Remote
   branches, and tags pushed to a remote, carry the remote's name as a
   separate segment.
diff --git a/docs/ROADMAP.jp.md b/docs/ROADMAP.jp.md
index ba436de..04a3cdf 100644
--- a/docs/ROADMAP.jp.md
+++ b/docs/ROADMAP.jp.md
@@ -51,6 +51,7 @@
   - Codeberg / Forgejo / Gitea: `fj` または REST API
 - **縮退規則**: CLI 不在・未認証・対象外ホストでは静かに無効（現行の gh と同じ）
 - リモート URL 正規化（`github_web_url`）をフォージ別のプロバイダに一般化するところから始める
+- **自前で立てたホスト**: コミットメニューの Web ページ（`commit_url_base`）は、github.com と gitlab.com を名前で判別するだけである。自前の GitLab や GitHub Enterprise はホスト名だけでは見分けられないので、ホストとそのフォージを指定する設定が要る
 
 ## 作業ツリー（ADR 0027 / 0028 の残課題）
 
diff --git a/docs/ROADMAP.md b/docs/ROADMAP.md
index fbe5fce..47ae943 100644
--- a/docs/ROADMAP.md
+++ b/docs/ROADMAP.md
@@ -67,6 +67,10 @@ keyed off the remote URL's host.
   on unknown hosts (same as gh today)
 - Start by generalizing the remote-URL normalization (`github_web_url`)
   into per-forge providers
+- **Self-hosted hosts**: the commit menu's web page (`commit_url_base`)
+  knows github.com and gitlab.com by name only. A self-hosted GitLab or
+  GitHub Enterprise cannot be told from other hosts by its name, so it needs
+  a setting that names the host and its forge
 
 ## Working tree (follow-ups to ADR 0027 / 0028)
 
diff --git a/frontend/e2e/graph.spec.ts b/frontend/e2e/graph.spec.ts
index 76e3ccf..2ba0512 100644
--- a/frontend/e2e/graph.spec.ts
+++ b/frontend/e2e/graph.spec.ts
@@ -1695,6 +1695,52 @@ test.describe.serial("gitreant UI", () => {
     await expect(page.locator('[data-repo-name="repoK"]')).toHaveCount(0);
   });
 
+  test("the commit menu copies the hash and the commit's web page", async ({
+    page,
+    context,
+  }) => {
+    await context.grantPermissions(["clipboard-read", "clipboard-write"]);
+    await page.getByTestId("add-input").fill(fixtures.repoK);
+    await page.getByTestId("add-submit").click();
+    await expect(page.locator('[data-tab-name="repoK"]')).toBeVisible();
+
+    const node = page.getByTestId("graph-node").first();
+    const menu = page.getByTestId("commit-menu");
+    await node.click({ button: "right" });
+    await menu.getByTestId("commit-menu-copy-hash").click();
+    await expect(menu).toHaveCount(0);
+    const id = await page.evaluate(() => navigator.clipboard.readText());
+    expect(id).toMatch(/^[0-9a-f]{40}$/);
+
+    // repoK's origin is on github.com: its commit page can be copied or
+    // opened in a new tab.
+    const url = `https://github.com/example/repoK/commit/${id}`;
+    await node.click({ button: "right" });
+    await menu.getByTestId("commit-menu-copy-url").click();
+    await expect(menu).toHaveCount(0);
+    expect(await page.evaluate(() => navigator.clipboard.readText())).toBe(url);
+
+    // The page opens in a new tab (stubbed: the test never goes online),
+    // and the menu closes behind it.
+    await context.route("https://github.com/**", (route) =>
+      route.fulfill({ body: "stub" }),
+    );
+    await node.click({ button: "right" });
+    const [tab] = await Promise.all([
+      context.waitForEvent("page"),
+      menu.getByTestId("commit-menu-open-url").click(),
+    ]);
+    expect(tab.url()).toBe(url);
+    await tab.close();
+    await expect(menu).toHaveCount(0);
+
+    // Restore the served set.
+    const repoK = page.locator('[data-repo-name="repoK"]');
+    await repoK.hover();
+    await repoK.getByTestId("repo-remove").click();
+    await expect(page.locator('[data-repo-name="repoK"]')).toHaveCount(0);
+  });
+
   test("the branch badge menu copies, checks out and merges", async ({
     page,
     context,
@@ -2068,6 +2114,10 @@ test.describe.serial("gitreant UI", () => {
     const menu = page.getByTestId("commit-menu");
     await expect(menu).toBeVisible();
     await expect(menu.locator(".ctx-menu-note")).toHaveText(shown);
+    // repoA has no origin on a known host, so no web page to offer.
+    await expect(menu.getByTestId("commit-menu-copy-hash")).toBeVisible();
+    await expect(menu.getByTestId("commit-menu-copy-url")).toHaveCount(0);
+    await expect(menu.getByTestId("commit-menu-open-url")).toHaveCount(0);
     await page.keyboard.press("Escape");
     await expect(menu).toHaveCount(0);
 
diff --git a/frontend/src/CommitMenu.tsx b/frontend/src/CommitMenu.tsx
index 08a6e8c..aa07a27 100644
--- a/frontend/src/CommitMenu.tsx
+++ b/frontend/src/CommitMenu.tsx
@@ -3,14 +3,16 @@ import { shortId } from "./graph";
 import { useT } from "./settings";
 
 /**
- * Context menu on a commit row: a list of actions first (create tag, create
- * branch), and a name input once one is chosen — so further commands can
- * slot in without fighting an always-open input.
+ * Context menu on a commit row or node: a list of actions first (copy the
+ * id, copy or open the commit's web page, create tag, create branch), and a
+ * name input once a ref is to be created — so further commands can slot in
+ * without fighting an always-open input.
  */
 export function CommitMenu({
   x,
   y,
   commit,
+  webUrl,
   onCreateTag,
   onCreateBranch,
   onClose,
@@ -19,6 +21,8 @@ export function CommitMenu({
   y: number;
   /** The full commit id the actions apply to. */
   commit: string;
+  /** The commit's page on the origin's host; absent when it has none. */
+  webUrl?: string;
   onCreateTag: (name: string) => void;
   onCreateBranch: (name: string) => void;
   onClose: () => void;
@@ -26,6 +30,10 @@ export function CommitMenu({
   const t = useT();
   const [stage, setStage] = useState<"tag" | "branch" | null>(null);
   const [name, setName] = useState("");
+  const copyAndClose = (text: string) => {
+    navigator.clipboard?.writeText(text).catch(() => {});
+    onClose();
+  };
 
   useEffect(() => {
     const close = (e: MouseEvent | KeyboardEvent) => {
@@ -50,6 +58,34 @@ export function CommitMenu({
       <span className="ctx-menu-note">{shortId(commit)}</span>
       {stage === null ? (
         <>
+          <button
+            type="button"
+            data-testid="commit-menu-copy-hash"
+            onClick={() => copyAndClose(commit)}
+          >
+            {t("copyCommitId")}
+          </button>
+          {webUrl && (
+            <>
+              <button
+                type="button"
+                data-testid="commit-menu-copy-url"
+                onClick={() => copyAndClose(webUrl)}
+              >
+                {t("copyCommitUrl")}
+              </button>
+              <a
+                data-testid="commit-menu-open-url"
+                href={webUrl}
+                target="_blank"
+                rel="noreferrer"
+                onClick={onClose}
+                onAuxClick={onClose}
+              >
+                {t("openCommitUrl")}
+              </a>
+            </>
+          )}
           <button
             type="button"
             data-testid="commit-menu-tag"
diff --git a/frontend/src/RepoCard.tsx b/frontend/src/RepoCard.tsx
index c8d5ccf..facc766 100644
--- a/frontend/src/RepoCard.tsx
+++ b/frontend/src/RepoCard.tsx
@@ -446,6 +446,10 @@ export function RepoCard({
           x={commitMenu.x}
           y={commitMenu.y}
           commit={commitMenu.commit}
+          webUrl={
+            repo.commit_url_base &&
+            `${repo.commit_url_base}${commitMenu.commit}`
+          }
           onCreateTag={(name) =>
             runBranchOp(
               (repoId, value) => createTag(repoId, value, commitMenu.commit),
diff --git a/frontend/src/api.ts b/frontend/src/api.ts
index c3de691..7ab31f5 100644
--- a/frontend/src/api.ts
+++ b/frontend/src/api.ts
@@ -87,6 +87,9 @@ export interface RepoView {
   head_branch?: string;
   /** Web URL of the origin remote, when it points at github.com. */
   github_url?: string;
+  /** A commit's web page on the origin's host (github.com or gitlab.com),
+   *  less the full commit id that completes it. */
+  commit_url_base?: string;
   /** The repository's other worktrees, so a branch badge can say where the
    *  branch is checked out (git refuses to switch to it here). */
   worktrees?: WorktreeEntry[];
diff --git a/frontend/src/i18n.ts b/frontend/src/i18n.ts
index aeb770e..854b84f 100644
--- a/frontend/src/i18n.ts
+++ b/frontend/src/i18n.ts
@@ -135,6 +135,9 @@ const en = {
   tagNamePlaceholder: "Tag name…",
   createBranch: "Create branch",
   branchNamePlaceholder: "Branch name…",
+  copyCommitId: "Copy commit id",
+  copyCommitUrl: "Copy web page URL",
+  openCommitUrl: "Open web page",
   // Commit details
   loading: "Loading…",
   expandBody: "Show full message",
@@ -293,6 +296,9 @@ const ja: Record<MsgKey, string> = {
   tagNamePlaceholder: "タグ名…",
   createBranch: "ブランチを作成",
   branchNamePlaceholder: "ブランチ名…",
+  copyCommitId: "コミットIDをコピー",
+  copyCommitUrl: "WebページのURLをコピー",
+  openCommitUrl: "Webページを開く",
   loading: "読み込み中…",
   expandBody: "全文を表示",
   collapseBody: "本文をたたむ",
diff --git a/frontend/src/stories/CommitMenu.stories.tsx b/frontend/src/stories/CommitMenu.stories.tsx
index 6a005d6..19360a7 100644
--- a/frontend/src/stories/CommitMenu.stories.tsx
+++ b/frontend/src/stories/CommitMenu.stories.tsx
@@ -21,3 +21,13 @@ export const Default: Story = {
     onClose: () => console.log("close"),
   },
 };
+
+/** The origin is on github.com or gitlab.com: the commit's web page joins
+ * the actions. */
+export const WithWebPage: Story = {
+  args: {
+    ...Default.args,
+    webUrl:
+      "https://github.com/ShortArrow/gitreant/commit/4043bc624ad30d6cd059d892a8ceb3b7cc9da79a",
+  },
+};
diff --git a/frontend/src/styles.css b/frontend/src/styles.css
index a1a0481..630a441 100644
--- a/frontend/src/styles.css
+++ b/frontend/src/styles.css
@@ -1081,7 +1081,8 @@ body {
 }
 
 .ref-menu button,
-.ctx-menu button {
+.ctx-menu button,
+.ctx-menu a {
   text-align: left;
   padding: 6px 10px;
   background: transparent;
@@ -1092,10 +1093,12 @@ body {
   font-size: 13px;
   font-family: system-ui, -apple-system, "Segoe UI", sans-serif;
   white-space: nowrap;
+  text-decoration: none;
 }
 
 .ref-menu button:hover:not(:disabled),
-.ctx-menu button:hover:not(:disabled) {
+.ctx-menu button:hover:not(:disabled),
+.ctx-menu a:hover {
   background: color-mix(in srgb, var(--accent) 14%, transparent);
 }
 
diff --git a/src/app/view.rs b/src/app/view.rs
index 163b46a..4c9e54d 100644
--- a/src/app/view.rs
+++ b/src/app/view.rs
@@ -89,6 +89,10 @@ pub struct RepoView {
     /// Web URL of the origin remote, when it points at github.com.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub github_url: Option<String>,
+    /// A commit's web page on the origin's host (github.com or gitlab.com),
+    /// less the full commit id that completes it.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub commit_url_base: Option<String>,
     /// The repository's other worktrees, so branch badges can say where a
     /// branch is checked out (a branch cannot be switched to twice).
     #[serde(skip_serializing_if = "Vec::is_empty")]
@@ -118,6 +122,7 @@ impl RepoView {
             head: None,
             head_branch: None,
             github_url: None,
+            commit_url_base: None,
             worktrees: Vec::new(),
             refs: Vec::new(),
             commits: Vec::new(),
@@ -330,6 +335,7 @@ pub fn build_view(id: &Path, data: &RepoData, uncommitted: usize) -> RepoView {
         head: data.head.clone(),
         head_branch: data.head_branch.clone(),
         github_url: data.github_url.clone(),
+        commit_url_base: data.commit_url_base.clone(),
         worktrees,
         refs,
         total: data.commits.len(),
@@ -382,6 +388,7 @@ mod tests {
             head: None,
             head_branch: None,
             github_url: None,
+            commit_url_base: None,
             worktrees: vec![],
         };
 
@@ -419,6 +426,7 @@ mod tests {
             head: head.map(str::to_string),
             head_branch: head.map(|_| "main".to_string()),
             github_url: None,
+            commit_url_base: None,
             worktrees: vec![],
         }
     }
@@ -489,6 +497,7 @@ mod tests {
             head: Some("A".to_string()),
             head_branch: Some("main".to_string()),
             github_url: None,
+            commit_url_base: None,
             worktrees: vec![],
         };
 
diff --git a/src/git/repo.rs b/src/git/repo.rs
index 33398aa..2b9067e 100644
--- a/src/git/repo.rs
+++ b/src/git/repo.rs
@@ -56,6 +56,9 @@ pub struct RepoData {
     pub head_branch: Option<String>,
     /// Web URL of the origin remote, when it points at github.com.
     pub github_url: Option<String>,
+    /// A commit's web page on the origin's host, less the full commit id
+    /// (`commit_url_base`).
+    pub commit_url_base: Option<String>,
     /// The repository's other worktrees (`git worktree`): the main one when
     /// this is a linked worktree, and every linked one otherwise.
     pub worktrees: Vec<Worktree>,
@@ -111,10 +114,12 @@ pub fn read_repo_with_progress(
         .ok()
         .flatten()
         .map(|name| name.shorten().to_string());
-    let github_url = repo
+    let origin_url = repo
         .config_snapshot()
         .string("remote.origin.url")
-        .and_then(|url| github_web_url(&url.to_string()));
+        .map(|url| url.to_string());
+    let github_url = origin_url.as_deref().and_then(github_web_url);
+    let commit_url_base = origin_url.as_deref().and_then(commit_url_base);
 
     let tips: Vec<gix::ObjectId> = refs
         .iter()
@@ -139,6 +144,7 @@ pub fn read_repo_with_progress(
         head,
         head_branch,
         github_url,
+        commit_url_base,
         worktrees: read_worktrees(path),
     })
 }
@@ -205,18 +211,50 @@ fn classify(full: &str, short: &str) -> (String, Option<String>, String) {
 /// Handles "https://github.com/o/r(.git)", "git@github.com:o/r(.git)" and
 /// "ssh://git@github.com/o/r(.git)"; anything else is None.
 pub fn github_web_url(clone_url: &str) -> Option<String> {
+    let path = repo_path_on("github.com", clone_url)?;
+    let mut parts = path.splitn(2, '/');
+    let owner = parts.next().filter(|s| !s.is_empty())?;
+    let repo = parts.next().filter(|s| !s.is_empty() && !s.contains('/'))?;
+    Some(format!("https://github.com/{owner}/{repo}"))
+}
+
+/// The web page of a commit on the origin's host, less the full commit id
+/// that completes it, when the origin is on github.com or gitlab.com.
+/// A GitLab project may sit in nested groups ("group/sub/repo"); a
+/// self-hosted GitLab cannot be told from other hosts by name, so it is None.
+pub fn commit_url_base(clone_url: &str) -> Option<String> {
+    if let Some(repo) = github_web_url(clone_url) {
+        return Some(format!("{repo}/commit/"));
+    }
+    let path = repo_path_on("gitlab.com", clone_url)?;
+    let segments: Vec<&str> = path.split('/').collect();
+    if segments.len() < 2 || segments.iter().any(|s| s.is_empty()) {
+        return None;
+    }
+    Some(format!("https://gitlab.com/{path}/-/commit/"))
+}
+
+/// The repository path of a clone URL on `host`, in its HTTPS, scp-like or
+/// `ssh://` form, without ".git" and trailing slashes. None unless every
+/// segment is a plain name (letters, digits, `.`, `_`, `-`; not `.`, `..`
+/// or GitLab's `-` separator) and the path is not a wiki's.
+fn repo_path_on<'a>(host: &str, clone_url: &'a str) -> Option<&'a str> {
     let rest = clone_url
-        .strip_prefix("https://github.com/")
-        .or_else(|| clone_url.strip_prefix("git@github.com:"))
-        .or_else(|| clone_url.strip_prefix("ssh://git@github.com/"))?;
+        .strip_prefix(&format!("https://{host}/"))
+        .or_else(|| clone_url.strip_prefix(&format!("git@{host}:")))
+        .or_else(|| clone_url.strip_prefix(&format!("ssh://git@{host}/")))?
+        .trim_end_matches('/');
     let path = rest
         .strip_suffix(".git")
         .unwrap_or(rest)
         .trim_end_matches('/');
-    let mut parts = path.splitn(2, '/');
-    let owner = parts.next().filter(|s| !s.is_empty())?;
-    let repo = parts.next().filter(|s| !s.is_empty() && !s.contains('/'))?;
-    Some(format!("https://github.com/{owner}/{repo}"))
+    let plain = |segment: &str| {
+        !matches!(segment, "" | "." | ".." | "-")
+            && segment
+                .chars()
+                .all(|c| c.is_ascii_alphanumeric() || matches!(c, '.' | '_' | '-'))
+    };
+    (path.split('/').all(plain) && !path.ends_with(".wiki")).then_some(path)
 }
 
 /// A commit collected before ordering.
@@ -441,6 +479,61 @@ mod tests {
         assert_eq!(github_web_url("https://github.com/only-owner"), None);
     }
 
+    #[test]
+    fn commit_url_base_follows_the_host_s_commit_page() {
+        assert_eq!(
+            commit_url_base("git@github.com:owner/repo.git").as_deref(),
+            Some("https://github.com/owner/repo/commit/")
+        );
+        for url in [
+            "https://gitlab.com/group/sub/repo.git",
+            "https://gitlab.com/group/sub/repo",
+            "git@gitlab.com:group/sub/repo.git",
+            "ssh://git@gitlab.com/group/sub/repo.git",
+        ] {
+            assert_eq!(
+                commit_url_base(url).as_deref(),
+                Some("https://gitlab.com/group/sub/repo/-/commit/"),
+                "for {url}"
+            );
+        }
+    }
+
+    #[test]
+    fn commit_url_base_rejects_other_hosts_and_shapes() {
+        assert_eq!(commit_url_base("https://gitlab.example.com/o/r.git"), None);
+        assert_eq!(commit_url_base("https://gitlab.com/only-group"), None);
+        assert_eq!(commit_url_base("https://gitlab.com/group//repo"), None);
+        assert_eq!(commit_url_base("../local/path"), None);
+    }
+
+    #[test]
+    fn commit_url_base_drops_a_git_suffix_before_a_trailing_slash() {
+        assert_eq!(
+            commit_url_base("https://github.com/o/r.git/").as_deref(),
+            Some("https://github.com/o/r/commit/")
+        );
+        assert_eq!(
+            commit_url_base("https://gitlab.com/g/r.git/").as_deref(),
+            Some("https://gitlab.com/g/r/-/commit/")
+        );
+    }
+
+    #[test]
+    fn commit_url_base_rejects_paths_that_name_no_project() {
+        for url in [
+            "https://github.com/o/r.wiki.git",
+            "https://gitlab.com/g/s/r.wiki.git",
+            "https://gitlab.com/g/r?private_token=T",
+            "https://github.com/o/r#frag",
+            "git@gitlab.com:g/r.git ",
+            "https://gitlab.com/g/r/-/tree/main",
+            "https://gitlab.com/g/../r",
+        ] {
+            assert_eq!(commit_url_base(url), None, "for {url}");
+        }
+    }
+
     fn oid(hex: &str) -> gix::ObjectId {
         gix::ObjectId::from_hex(hex.as_bytes()).expect("valid 40-hex object id")
     }