diff --git a/app/api.py b/app/api.py
new file mode 100644
index 0000000..4cc7cb0
--- /dev/null
+++ b/app/api.py
@@ -0,0 +1,92 @@
+from typing import Annotated
+from uuid import UUID
+
+from fastapi import APIRouter, Depends, HTTPException, Request, Response, status
+
+from app.checker import EndpointChecker
+from app.models import CurrentStatus, Monitor, MonitorCreate, MonitorUpdate
+from app.store import MonitorStore
+
+router = APIRouter()
+
+
+def store(request: Request) -> MonitorStore:
+    return request.app.state.store
+
+
+def checker(request: Request) -> EndpointChecker:
+    return request.app.state.checker
+
+
+Store = Annotated[MonitorStore, Depends(store)]
+Checker = Annotated[EndpointChecker, Depends(checker)]
+
+
+def missing() -> HTTPException:
+    return HTTPException(status_code=404, detail=("monitor_not_found", "Monitor not found"))
+
+
+@router.post("/v1/monitors", response_model=Monitor, status_code=status.HTTP_201_CREATED)
+async def create_monitor(data: MonitorCreate, state: Store) -> Monitor:
+    return await state.create(data)
+
+
+@router.get("/v1/monitors", response_model=list[Monitor])
+async def list_monitors(state: Store) -> list[Monitor]:
+    return await state.list()
+
+
+@router.get("/v1/monitors/{monitor_id}", response_model=Monitor)
+async def get_monitor(monitor_id: UUID, state: Store) -> Monitor:
+    item = await state.get(monitor_id)
+    if item is None:
+        raise missing()
+    return item
+
+
+@router.patch("/v1/monitors/{monitor_id}", response_model=Monitor)
+async def update_monitor(monitor_id: UUID, data: MonitorUpdate, state: Store) -> Monitor:
+    item = await state.update(monitor_id, data)
+    if item is None:
+        raise missing()
+    return item
+
+
+@router.delete("/v1/monitors/{monitor_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def delete_monitor(monitor_id: UUID, state: Store) -> Response:
+    if not await state.delete(monitor_id):
+        raise missing()
+    return Response(status_code=status.HTTP_204_NO_CONTENT)
+
+
+@router.post("/v1/monitors/{monitor_id}/check", response_model=CurrentStatus)
+async def check_monitor(monitor_id: UUID, state: Store, outbound: Checker) -> CurrentStatus:
+    snapshot = await state.snapshot(monitor_id)
+    if snapshot is None:
+        raise missing()
+    item, revision = snapshot
+    result = await outbound.check(str(item.url))
+    if await state.record_status(monitor_id, revision, result) is None:
+        raise HTTPException(status_code=409,
+                            detail=("monitor_changed", "Monitor changed while check was running"))
+    return result
+
+
+@router.get("/v1/monitors/{monitor_id}/status", response_model=CurrentStatus)
+async def get_status(monitor_id: UUID, state: Store) -> CurrentStatus:
+    item = await state.get(monitor_id)
+    if item is None:
+        raise missing()
+    return item.current_status
+
+
+@router.get("/healthz")
+async def health() -> dict[str, str]:
+    return {"status": "ok"}
+
+
+@router.get("/readyz")
+async def readiness(request: Request) -> dict[str, str]:
+    if not hasattr(request.app.state, "store"):
+        raise HTTPException(status_code=503, detail=("not_ready", "Service is not ready"))
+    return {"status": "ready", "storage": "process-local-memory"}