diff --git a/core/frontend/vite.config.js b/core/frontend/vite.config.js
index e64d828b69..5462c262a4 100644
--- a/core/frontend/vite.config.js
+++ b/core/frontend/vite.config.js
@@ -133,6 +133,9 @@ export default defineConfig(({ command, mode }) => {
         '^/bag': {
           target: SERVER_ADDRESS,
         },
+        '^/odometer': {
+          target: SERVER_ADDRESS,
+        },
         '^/beacon': {
           target: SERVER_ADDRESS,
         },
diff --git a/core/services/helper/main.py b/core/services/helper/main.py
index 7be21e1c9d..874887b292 100755
--- a/core/services/helper/main.py
+++ b/core/services/helper/main.py
@@ -160,6 +160,7 @@ class Helper:
         9110,  # Ping Service
         9111,  # Beacon Service
         9120,  # Pardal
+        9127,  # Odometer
         9134,  # Kraken
         27353,  # Bridget
     }
diff --git a/core/services/odometer/main.py b/core/services/odometer/main.py
new file mode 100644
index 0000000000..a9a9d3660e
--- /dev/null
+++ b/core/services/odometer/main.py
@@ -0,0 +1,347 @@
+#! /usr/bin/env python3
+import argparse
+import asyncio
+import json
+import logging
+import math
+import os
+from dataclasses import asdict, dataclass
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import Any, Optional
+
+import appdirs
+import zenoh
+from commonwealth.utils.apis import GenericErrorHandlingRoute
+from commonwealth.utils.logs import InterceptHandler, init_logger
+from commonwealth.utils.sentry_config import init_sentry_async
+from fastapi import APIRouter, Depends, FastAPI, HTTPException, status
+from fastapi.responses import HTMLResponse
+from fastapi_versioning import VersionedFastAPI, version, versioned_api_route
+from loguru import logger
+from pydantic import BaseModel, Field
+from uvicorn import Config, Server
+
+SERVICE_NAME = "odometer"
+DEFAULT_DATA_DIR = Path(appdirs.user_data_dir(SERVICE_NAME, "blueos"))
+DEFAULT_STATE_PATH = DEFAULT_DATA_DIR / "odometer.json"
+DEFAULT_KEY_EXPR = "mavlink/**/GLOBAL_POSITION_INT"
+
+parser = argparse.ArgumentParser(description="Odometer service using Zenoh")
+parser.add_argument(
+    "--port",
+    type=int,
+    default=9127,
+    help="Port to run the HTTP server on (default: 9127).",
+)
+parser.add_argument(
+    "--state-path",
+    type=str,
+    default=os.environ.get("ODOMETER_STATE_PATH", str(DEFAULT_STATE_PATH)),
+    help="Path to the odometer JSON state file.",
+)
+parser.add_argument(
+    "--zenoh-config",
+    type=str,
+    default=os.environ.get("ODOMETER_ZENOH_CONFIG"),
+    help="Optional path to a Zenoh JSON/JSON5 configuration file.",
+)
+parser.add_argument(
+    "--key-expr",
+    type=str,
+    default=os.environ.get("ODOMETER_KEY_EXPR", DEFAULT_KEY_EXPR),
+    help="Zenoh key expression to subscribe to for position updates.",
+)
+parser.add_argument(
+    "--persist-interval",
+    type=float,
+    default=float(os.environ.get("ODOMETER_PERSIST_SECONDS", "5")),
+    help="Interval in seconds to persist odometer state to disk.",
+)
+
+args = parser.parse_args()
+
+logging.basicConfig(handlers=[InterceptHandler()], level=0)
+init_logger(SERVICE_NAME)
+
+EARTH_RADIUS_M = 6_371_000.0
+
+
+class Position(BaseModel):
+    lat_deg: float = Field(..., description="Latitude in degrees.")
+    lon_deg: float = Field(..., description="Longitude in degrees.")
+    alt_m: Optional[float] = Field(None, description="Altitude in meters if available.")
+    time_boot_ms: Optional[int] = Field(None, description="ArduPilot boot timestamp in milliseconds.")
+
+
+class OdometerState(BaseModel):
+    total_distance_m: float = Field(0, ge=0, description="Total distance traveled in meters.")
+    last_position: Optional[Position] = None
+    sample_count: int = Field(0, ge=0, description="Number of processed position samples.")
+    updated_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
+
+
+@dataclass
+class _RawState:
+    total_distance_m: float
+    last_position: Optional[dict[str, Any]]
+    sample_count: int
+    updated_at: str
+
+
+def _haversine_distance_m(pos_a: Position, pos_b: Position) -> float:
+    """Compute great-circle distance between two positions in meters."""
+    lat1, lon1, lat2, lon2 = map(math.radians, (pos_a.lat_deg, pos_a.lon_deg, pos_b.lat_deg, pos_b.lon_deg))
+    dlat = lat2 - lat1
+    dlon = lon2 - lon1
+
+    a_term = math.sin(dlat / 2) ** 2 + math.cos(lat1) * math.cos(lat2) * math.sin(dlon / 2) ** 2
+    c_term = 2 * math.asin(min(1.0, math.sqrt(a_term)))
+    return EARTH_RADIUS_M * c_term
+
+
+class OdometerService:
+    def __init__(
+        self,
+        state_path: Path,
+        key_expr: str,
+        zenoh_config_path: Optional[Path],
+        persist_interval_seconds: float,
+    ) -> None:
+        self.state_path = state_path
+        self.key_expr = key_expr
+        self.zenoh_config_path = zenoh_config_path
+        self.persist_interval_seconds = max(1.0, persist_interval_seconds)
+
+        self._state: OdometerState = OdometerState()
+        self._lock = asyncio.Lock()
+        self._session: Optional[zenoh.Session] = None
+        self._subscriber: Optional[zenoh.Subscriber] = None
+        self._persist_task: Optional[asyncio.Task[None]] = None
+        self._loop: Optional[asyncio.AbstractEventLoop] = None
+
+    async def start(self) -> None:
+        logger.info(
+            "Starting odometer service - state_path=%s key_expr=%s zenoh_config=%s",
+            self.state_path,
+            self.key_expr,
+            self.zenoh_config_path,
+        )
+        self._loop = asyncio.get_running_loop()
+        self.state_path.parent.mkdir(parents=True, exist_ok=True)
+        self._state = await asyncio.to_thread(self._load_state)
+
+        self._session = await asyncio.to_thread(self._open_session)
+        try:
+            self._subscriber = self._session.declare_subscriber(self.key_expr, self._on_sample)
+        except Exception as exc:
+            logger.exception("Failed to declare Zenoh subscriber")
+            await asyncio.to_thread(self._session.close)
+            raise exc
+
+        self._persist_task = asyncio.create_task(self._persist_state_periodically())
+        logger.info("Odometer service started")
+
+    async def stop(self) -> None:
+        logger.info("Stopping odometer service")
+        if self._persist_task:
+            self._persist_task.cancel()
+            try:
+                await self._persist_task
+            except asyncio.CancelledError:
+                pass
+
+        if self._subscriber:
+            await asyncio.to_thread(self._subscriber.undeclare)
+        if self._session:
+            await asyncio.to_thread(self._session.close)
+        await self.persist_state()
+        logger.info("Odometer service stopped")
+
+    def _open_session(self) -> zenoh.Session:
+        config = (
+            zenoh.Config.from_file(str(self.zenoh_config_path))
+            if self.zenoh_config_path is not None
+            else zenoh.Config()
+        )
+        if self.zenoh_config_path is None:
+            config.insert_json5("mode", json.dumps("client"))
+            config.insert_json5("connect/endpoints", json.dumps(["tcp/127.0.0.1:7447"]))
+            config.insert_json5("metadata", json.dumps({"name": SERVICE_NAME}))
+        return zenoh.open(config)
+
+    def _load_state(self) -> OdometerState:
+        if not self.state_path.exists():
+            return OdometerState()
+        try:
+            with self.state_path.open("r", encoding="utf-8") as state_file:
+                payload: _RawState = _RawState(**json.load(state_file))
+            last_position = Position(**payload.last_position) if payload.last_position else None
+            return OdometerState(
+                total_distance_m=payload.total_distance_m,
+                last_position=last_position,
+                sample_count=payload.sample_count,
+                updated_at=datetime.fromisoformat(payload.updated_at),
+            )
+        except Exception:
+            logger.exception("Failed to load odometer state from %s, starting fresh", self.state_path)
+            return OdometerState()
+
+    def _on_sample(self, sample: zenoh.Sample) -> None:
+        if self._loop is None:
+            logger.debug("Ignoring sample before event loop is ready")
+            return
+
+        try:
+            payload_text = sample.payload.to_string()
+            payload_json = json.loads(payload_text)
+            message = payload_json.get("message", {})
+            lat_raw = message.get("lat")
+            lon_raw = message.get("lon")
+            if lat_raw is None or lon_raw is None:
+                return
+            lat_deg = float(lat_raw) / 1e7
+            lon_deg = float(lon_raw) / 1e7
+            alt_raw = message.get("alt")
+            alt_m = float(alt_raw) / 1000 if isinstance(alt_raw, (int, float)) else None
+            time_boot_ms = message.get("time_boot_ms")
+            position = Position(lat_deg=lat_deg, lon_deg=lon_deg, alt_m=alt_m, time_boot_ms=time_boot_ms)
+
+            asyncio.run_coroutine_threadsafe(self.update_position(position), self._loop)
+        except json.JSONDecodeError:
+            logger.debug("Received non-JSON sample on %s: %s", self.key_expr, sample)
+        except Exception:
+            logger.exception("Failed to handle Zenoh sample")
+
+    async def update_position(self, position: Position) -> None:
+        async with self._lock:
+            if self._state.last_position:
+                try:
+                    delta_m = _haversine_distance_m(self._state.last_position, position)
+                except ValueError:
+                    delta_m = 0
+                if math.isfinite(delta_m) and delta_m >= 0:
+                    self._state.total_distance_m += delta_m
+            self._state.last_position = position
+            self._state.sample_count += 1
+            self._state.updated_at = datetime.now(timezone.utc)
+
+    async def get_state(self) -> OdometerState:
+        async with self._lock:
+            return OdometerState.parse_obj(self._state.dict())
+
+    async def reset(self) -> OdometerState:
+        async with self._lock:
+            self._state = OdometerState()
+        await self.persist_state()
+        return await self.get_state()
+
+    def _serialize_state(self) -> _RawState:
+        return _RawState(
+            total_distance_m=self._state.total_distance_m,
+            last_position=self._state.last_position.dict() if self._state.last_position else None,
+            sample_count=self._state.sample_count,
+            updated_at=self._state.updated_at.isoformat(),
+        )
+
+    async def persist_state(self) -> None:
+        async with self._lock:
+            serialized = asdict(self._serialize_state())
+        await asyncio.to_thread(self._write_state, serialized)
+
+    def _write_state(self, serialized: dict[str, Any]) -> None:
+        self.state_path.parent.mkdir(parents=True, exist_ok=True)
+        with self.state_path.open("w", encoding="utf-8") as state_file:
+            json.dump(serialized, state_file, indent=2)
+
+    async def _persist_state_periodically(self) -> None:
+        while True:
+            try:
+                await asyncio.sleep(self.persist_interval_seconds)
+                await self.persist_state()
+            except asyncio.CancelledError:
+                return
+            except Exception:
+                logger.exception("Failed during periodic persistence loop iteration")
+
+
+state_path = Path(args.state_path)
+zenoh_config_path = Path(args.zenoh_config) if args.zenoh_config else None
+odometer_service = OdometerService(
+    state_path=state_path,
+    key_expr=args.key_expr,
+    zenoh_config_path=zenoh_config_path,
+    persist_interval_seconds=args.persist_interval,
+)
+
+
+def get_odometer_service() -> OdometerService:
+    return odometer_service
+
+
+api_router = APIRouter(
+    prefix="/odometer",
+    tags=["odometer_v1"],
+    route_class=versioned_api_route(1, 0),
+    responses={
+        status.HTTP_500_INTERNAL_SERVER_ERROR: {"description": "Internal server error"},
+    },
+)
+
+
+@api_router.get("/", response_model=OdometerState, summary="Get odometer state.")
+@version(1, 0)
+async def read_state(service: OdometerService = Depends(get_odometer_service)) -> OdometerState:
+    return await service.get_state()
+
+
+class ResetResponse(BaseModel):
+    status: str = Field("reset", description="Status message for reset operation.")
+    state: OdometerState
+
+
+@api_router.post("/reset", response_model=ResetResponse, summary="Reset odometer.")
+@version(1, 0)
+async def reset_state(service: OdometerService = Depends(get_odometer_service)) -> ResetResponse:
+    state = await service.reset()
+    return ResetResponse(state=state)
+
+
+fastapi_app = FastAPI(
+    title="Odometer API",
+    description="Accumulate distance traveled from MAVLink positions received via Zenoh.",
+)
+fastapi_app.router.route_class = GenericErrorHandlingRoute
+fastapi_app.include_router(api_router)
+
+
+@fastapi_app.get("/", include_in_schema=False)
+async def root() -> HTMLResponse:
+    return HTMLResponse("<html><head><title>Odometer</title></head></html>")
+
+@fastapi_app.on_event("startup")
+async def on_startup() -> None:
+    await init_sentry_async(SERVICE_NAME)
+    try:
+        await odometer_service.start()
+    except Exception as exc:
+        logger.exception("Failed to start odometer service")
+        raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail=str(exc)) from exc
+
+
+@fastapi_app.on_event("shutdown")
+async def on_shutdown() -> None:
+    await odometer_service.stop()
+
+
+app = VersionedFastAPI(fastapi_app, version="1.0.0", prefix_format="/v{major}.{minor}", enable_latest=True)
+
+
+async def main() -> None:
+    config = Config(app=app, host="0.0.0.0", port=args.port, log_config=None)
+    server = Server(config)
+    await server.serve()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())
diff --git a/core/services/odometer/pyproject.toml b/core/services/odometer/pyproject.toml
new file mode 100644
index 0000000000..b861387a31
--- /dev/null
+++ b/core/services/odometer/pyproject.toml
@@ -0,0 +1,21 @@
+[project]
+name = "odometer"
+version = "0.1.0"
+description = "Zenoh-powered odometer service for BlueOS."
+requires-python = ">=3.11"
+dependencies = [
+    "appdirs==1.4.4",
+    "commonwealth==0.1.0",
+    "eclipse-zenoh==1.4.0",
+    "fastapi==0.105.0",
+    "fastapi-versioning==0.9.1",
+    "loguru==0.5.3",
+    "pydantic==1.10.12",
+    "uvicorn==0.18.0",
+]
+
+[tool.uv]
+package = false
+
+[tool.uv.sources]
+commonwealth = { workspace = true }
diff --git a/core/start-blueos-core b/core/start-blueos-core
index d3539d1bf9..b03bb5dfa7 100755
--- a/core/start-blueos-core
+++ b/core/start-blueos-core
@@ -133,6 +133,7 @@ SERVICES=(
     'ttyd',250,'nice -19 ttyd -p 8088 sh -c "/usr/bin/tmux attach -t user_terminal || /usr/bin/tmux new -s user_terminal"'
     'nginx',250,"nice -18 nginx -g \"daemon off;\" -c $TOOLS_PATH/nginx/nginx.conf"
     'bag_of_holding',250,"$SERVICES_PATH/bag_of_holding/main.py"
+    'odometer',250,"$SERVICES_PATH/odometer/main.py"
     'recorder',250,"blueos-recorder --recorder-path /usr/blueos/userdata/recorder"
 )
 
diff --git a/core/tools/nginx/nginx.conf b/core/tools/nginx/nginx.conf
index 7e259f3baf..3de5013679 100644
--- a/core/tools/nginx/nginx.conf
+++ b/core/tools/nginx/nginx.conf
@@ -80,6 +80,11 @@ http {
             proxy_pass http://127.0.0.1:9101/;
         }
 
+        location /odometer/ {
+            include cors.conf;
+            proxy_pass http://127.0.0.1:9127/;
+        }
+
         location /beacon/ {
             include cors.conf;
             proxy_pass http://127.0.0.1:9111/;