diff --git a/testjam-client/testjam_client/cli/__init__.py b/testjam-client/testjam_client/cli/__init__.py
index c0f7296..965f02c 100644
--- a/testjam-client/testjam_client/cli/__init__.py
+++ b/testjam-client/testjam_client/cli/__init__.py
@@ -5,6 +5,7 @@
 import httpx
 import typer
 
+from testjam_client.cli.commands import about as about_commands
 from testjam_client.cli.commands import auth as auth_commands
 from testjam_client.cli.commands import backup as backup_commands
 from testjam_client.cli.commands import bugs as bug_commands
@@ -133,3 +134,4 @@ def repl_command(context: typer.Context) -> None:
 app.add_typer(run_commands.build_app())
 app.add_typer(bug_commands.build_app())
 app.add_typer(backup_commands.build_app())
+app.add_typer(about_commands.build_app())
diff --git a/testjam-client/testjam_client/cli/commands/about.py b/testjam-client/testjam_client/cli/commands/about.py
new file mode 100644
index 0000000..ee5a45e
--- /dev/null
+++ b/testjam-client/testjam_client/cli/commands/about.py
@@ -0,0 +1,75 @@
+"""`testjam about` — show client + server build metadata."""
+from __future__ import annotations
+
+from dataclasses import asdict
+from importlib.metadata import PackageNotFoundError, version
+
+import httpx
+import typer
+
+from testjam_client.cli import output, runtime
+from testjam_client.cli.state import CliState
+
+
+PACKAGE_NAME = "testjam-client"
+UNKNOWN = "unknown"
+
+
+def build_app() -> typer.Typer:
+    app = typer.Typer(
+        name="about",
+        help="Show client + server build metadata.",
+        no_args_is_help=False,
+        invoke_without_command=True,
+    )
+    app.callback(invoke_without_command=True)(show_about)
+    return app
+
+
+def show_about(context: typer.Context) -> None:
+    if context.invoked_subcommand is not None:
+        return
+    state: CliState = context.obj
+    payload = {
+        "client_version": _client_version(),
+        "server_url": state.profile.get("url"),
+        "server_version": UNKNOWN,
+        "server_ref": UNKNOWN,
+        "server_commit": UNKNOWN,
+        "server_built_at": UNKNOWN,
+        "server_status": "unreachable",
+    }
+    server = _fetch_server(state)
+    if server is not None:
+        payload.update({
+            "server_version": server["version"],
+            "server_ref": server["ref"],
+            "server_commit": server["commit"],
+            "server_built_at": server["built_at"],
+            "server_status": "ok",
+        })
+    columns = [
+        "client_version",
+        "server_url",
+        "server_status",
+        "server_version",
+        "server_ref",
+        "server_commit",
+        "server_built_at",
+    ]
+    output.render(payload, columns=columns, json_mode=state.json_output)
+
+
+def _fetch_server(state: CliState) -> dict | None:
+    try:
+        with runtime.build_client(state) as client:
+            return asdict(client.about.get())
+    except (httpx.HTTPError, typer.BadParameter):
+        return None
+
+
+def _client_version() -> str:
+    try:
+        return version(PACKAGE_NAME)
+    except PackageNotFoundError:
+        return UNKNOWN
diff --git a/testjam-client/testjam_client/client.py b/testjam-client/testjam_client/client.py
index 05bd86d..a20a01b 100644
--- a/testjam-client/testjam_client/client.py
+++ b/testjam-client/testjam_client/client.py
@@ -17,6 +17,7 @@
 import httpx
 
 from testjam_client.errors import raise_for_status
+from testjam_client.resources.about import AboutResource
 from testjam_client.resources.backup import BackupResource
 from testjam_client.resources.bugs import BugsResource
 from testjam_client.resources.cases import CasesResource
@@ -85,6 +86,7 @@ def __init__(
         self.mentions = MentionsResource(self)
         self.public_reports = PublicReportsResource(self)
         self.backup = BackupResource(self)
+        self.about = AboutResource(self)
 
     def login(self, username: str, password: str) -> str:
         response = self._http.request(
diff --git a/testjam-client/testjam_client/resources/about.py b/testjam-client/testjam_client/resources/about.py
new file mode 100644
index 0000000..c064ec0
--- /dev/null
+++ b/testjam-client/testjam_client/resources/about.py
@@ -0,0 +1,25 @@
+"""Server `/about` — build metadata for the connected instance.
+
+Mirrors the FastAPI response. Public endpoint, no auth required, so this
+resource works against an unauthenticated client too (useful for
+compatibility checks before configuring credentials).
+"""
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from testjam_client.resources._base import Resource
+
+
+@dataclass(frozen=True)
+class ServerAbout:
+    version: str
+    ref: str
+    commit: str
+    built_at: str
+
+
+class AboutResource(Resource):
+    def get(self) -> ServerAbout:
+        response = self._request("GET", "/about")
+        return ServerAbout(**response.json())
diff --git a/testjam-client/tests/test_about.py b/testjam-client/tests/test_about.py
new file mode 100644
index 0000000..50dd0e6
--- /dev/null
+++ b/testjam-client/tests/test_about.py
@@ -0,0 +1,56 @@
+"""SDK AboutResource — maps `/about` JSON onto the ServerAbout dataclass.
+
+Uses a tiny `httpx.MockTransport` so the test stays decoupled from the
+backend in-process app — `/about` is public, so there is nothing to
+exercise on the server side beyond the JSON shape.
+"""
+from __future__ import annotations
+
+import httpx
+
+from testjam_client import TestjamClient
+from testjam_client.resources.about import ServerAbout
+
+
+SAMPLE = {
+    "version": "1.0.0",
+    "ref": "v1.0.0",
+    "commit": "abc1234",
+    "built_at": "2026-05-25T12:00:00Z",
+}
+
+
+def test_get_returns_serveraobout_dataclass():
+    sdk = _client_with_about(SAMPLE)
+
+    result = sdk.about.get()
+
+    assert isinstance(result, ServerAbout)
+    assert result == ServerAbout(**SAMPLE)
+
+
+def test_get_does_not_require_authentication():
+    sdk = _client_with_about(SAMPLE)
+    assert "Authorization" not in sdk._http.headers
+    assert "X-API-Key" not in sdk._http.headers
+
+    sdk.about.get()
+
+
+def test_dataclass_is_immutable():
+    payload = ServerAbout(**SAMPLE)
+    try:
+        payload.version = "2.0.0"
+    except Exception:
+        return
+    raise AssertionError("ServerAbout should be frozen")
+
+
+def _client_with_about(payload):
+    def handler(request: httpx.Request) -> httpx.Response:
+        assert request.url.path.endswith("/about")
+        return httpx.Response(200, json=payload)
+
+    transport = httpx.MockTransport(handler)
+    http = httpx.Client(base_url="http://testserver/api/v1", transport=transport)
+    return TestjamClient(http=http)
diff --git a/testjam-client/tests/test_cli_about.py b/testjam-client/tests/test_cli_about.py
new file mode 100644
index 0000000..a191fba
--- /dev/null
+++ b/testjam-client/tests/test_cli_about.py
@@ -0,0 +1,104 @@
+"""CLI smoke for `testjam about`.
+
+Patches `runtime.build_client` so the command receives a fake SDK whose
+`.about.get()` returns a canned `ServerAbout`. No backend dependency.
+"""
+from __future__ import annotations
+
+import json
+from contextlib import nullcontext
+
+import httpx
+import pytest
+from typer.testing import CliRunner
+
+from testjam_client.cli import app
+from testjam_client.resources.about import ServerAbout
+
+
+runner = CliRunner()
+
+
+@pytest.fixture
+def cli_config(tmp_path, monkeypatch):
+    config_file = tmp_path / "config.toml"
+    monkeypatch.setenv("TESTJAM_CONFIG", str(config_file))
+    config_file.write_text('[profiles.default]\nurl = "http://testserver/api/v1"\n')
+
+
+def test_about_prints_client_and_server_metadata(cli_config, monkeypatch):
+    monkeypatch.setattr(
+        "testjam_client.cli.commands.about.runtime.build_client",
+        lambda state: _FakeClient(_sample()),
+    )
+
+    result = runner.invoke(app, ["--json", "about"])
+
+    assert result.exit_code == 0, result.output
+    payload = json.loads(result.output)
+    assert payload["client_version"]
+    assert payload["server_url"] == "http://testserver/api/v1"
+    assert payload["server_status"] == "ok"
+    assert payload["server_version"] == "1.0.0"
+    assert payload["server_ref"] == "v1.0.0"
+    assert payload["server_commit"] == "abc1234"
+    assert payload["server_built_at"] == "2026-05-25T12:00:00Z"
+
+
+def test_about_falls_back_to_unreachable_on_network_error(cli_config, monkeypatch):
+    def boom(state):
+        raise httpx.ConnectError("nope")
+
+    monkeypatch.setattr(
+        "testjam_client.cli.commands.about.runtime.build_client",
+        boom,
+    )
+
+    result = runner.invoke(app, ["--json", "about"])
+
+    assert result.exit_code == 0, result.output
+    payload = json.loads(result.output)
+    assert payload["server_status"] == "unreachable"
+    assert payload["server_version"] == "unknown"
+    assert payload["client_version"]
+
+
+def test_about_falls_back_when_no_profile_url(tmp_path, monkeypatch):
+    config_file = tmp_path / "config.toml"
+    monkeypatch.setenv("TESTJAM_CONFIG", str(config_file))
+    config_file.write_text('[profiles.default]\n')
+
+    result = runner.invoke(app, ["--json", "about"])
+
+    assert result.exit_code == 0, result.output
+    payload = json.loads(result.output)
+    assert payload["server_status"] == "unreachable"
+    assert payload["server_url"] is None
+
+
+def _sample() -> ServerAbout:
+    return ServerAbout(
+        version="1.0.0",
+        ref="v1.0.0",
+        commit="abc1234",
+        built_at="2026-05-25T12:00:00Z",
+    )
+
+
+class _FakeAbout:
+    def __init__(self, payload: ServerAbout) -> None:
+        self._payload = payload
+
+    def get(self) -> ServerAbout:
+        return self._payload
+
+
+class _FakeClient:
+    def __init__(self, payload: ServerAbout) -> None:
+        self.about = _FakeAbout(payload)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *_args):
+        return None