diff --git a/src/main/java/com/slotline/availability/AvailabilityService.java b/src/main/java/com/slotline/availability/AvailabilityService.java
new file mode 100644
index 0000000..ffebaa9
--- /dev/null
+++ b/src/main/java/com/slotline/availability/AvailabilityService.java
@@ -0,0 +1,136 @@
+package com.slotline.availability;
+
+import com.slotline.availability.dto.BlackoutRequest;
+import com.slotline.availability.dto.OperatingHoursRequest;
+import com.slotline.common.AvailabilityViolationException;
+import com.slotline.common.InvalidReservationException;
+import com.slotline.reservation.Reservation;
+import com.slotline.reservation.ReservationRepository;
+import com.slotline.resource.Resource;
+import com.slotline.resource.ResourceService;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.LocalTime;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.util.List;
+
+@Service
+public class AvailabilityService {
+
+    private final OperatingHoursRepository operatingHours;
+    private final BlackoutDateRepository blackouts;
+    private final ReservationRepository reservations;
+    private final ResourceService resources;
+
+    public AvailabilityService(OperatingHoursRepository operatingHours, BlackoutDateRepository blackouts,
+                               ReservationRepository reservations, ResourceService resources) {
+        this.operatingHours = operatingHours;
+        this.blackouts = blackouts;
+        this.reservations = reservations;
+        this.resources = resources;
+    }
+
+    public void verifyOpen(Resource resource, Instant start, Instant end) {
+        ZoneId zone = ZoneId.of(resource.getZoneId());
+        ZonedDateTime zonedStart = start.atZone(zone);
+        ZonedDateTime zonedEnd = end.atZone(zone);
+
+        verifyOperatingHours(resource, zonedStart, zonedEnd);
+        verifyNotBlackedOut(resource, zonedStart.toLocalDate(), zonedEnd.toLocalDate());
+    }
+
+    public void verifyBuffer(Resource resource, Instant start, Instant end) {
+        int bufferMinutes = resource.getBufferMinutes();
+        if (bufferMinutes <= 0) {
+            return;
+        }
+        Duration buffer = Duration.ofMinutes(bufferMinutes);
+        List<Reservation> neighbours =
+                reservations.findActiveWithinWindow(resource.getId(), start.minus(buffer), end.plus(buffer));
+        if (!neighbours.isEmpty()) {
+            throw new AvailabilityViolationException(
+                    "Requested slot violates the " + bufferMinutes + " minute buffer around an existing reservation");
+        }
+    }
+
+    @Transactional
+    public List<OperatingHours> replaceOperatingHours(Long organizationId, Long resourceId,
+                                                      List<OperatingHoursRequest> windows) {
+        Resource resource = resources.require(organizationId, resourceId);
+        for (OperatingHoursRequest window : windows) {
+            if (!window.openTime().isBefore(window.closeTime())) {
+                throw new InvalidReservationException("openTime must be before closeTime");
+            }
+        }
+        operatingHours.deleteByResourceId(resource.getId());
+        List<OperatingHours> saved = windows.stream()
+                .map(window -> new OperatingHours(resource.getId(), window.dayOfWeek(), window.openTime(),
+                        window.closeTime()))
+                .map(operatingHours::save)
+                .toList();
+        return saved;
+    }
+
+    @Transactional(readOnly = true)
+    public List<OperatingHours> listOperatingHours(Long organizationId, Long resourceId) {
+        Resource resource = resources.require(organizationId, resourceId);
+        return operatingHours.findByResourceId(resource.getId());
+    }
+
+    @Transactional
+    public BlackoutDate addBlackout(Long organizationId, Long resourceId, BlackoutRequest request) {
+        Resource resource = resources.require(organizationId, resourceId);
+        if (request.endDate().isBefore(request.startDate())) {
+            throw new InvalidReservationException("endDate must not be before startDate");
+        }
+        return blackouts.save(new BlackoutDate(resource.getId(), request.startDate(), request.endDate(),
+                request.reason()));
+    }
+
+    @Transactional(readOnly = true)
+    public List<BlackoutDate> listBlackouts(Long organizationId, Long resourceId) {
+        Resource resource = resources.require(organizationId, resourceId);
+        return blackouts.findByResourceIdOrderByStartDateAsc(resource.getId());
+    }
+
+    @Transactional
+    public void removeBlackout(Long organizationId, Long resourceId, Long blackoutId) {
+        Resource resource = resources.require(organizationId, resourceId);
+        blackouts.findById(blackoutId)
+                .filter(blackout -> blackout.getResourceId().equals(resource.getId()))
+                .ifPresent(blackouts::delete);
+    }
+
+    private void verifyOperatingHours(Resource resource, ZonedDateTime zonedStart, ZonedDateTime zonedEnd) {
+        List<OperatingHours> resourceHours = operatingHours.findByResourceId(resource.getId());
+        if (resourceHours.isEmpty()) {
+            return;
+        }
+        if (!zonedStart.toLocalDate().equals(zonedEnd.toLocalDate())) {
+            throw new AvailabilityViolationException(
+                    "Reservation must fall within a single day of the resource operating hours");
+        }
+        LocalTime openAt = zonedStart.toLocalTime();
+        LocalTime closeAt = zonedEnd.toLocalTime();
+        boolean withinAnyWindow = resourceHours.stream()
+                .filter(window -> window.getDayOfWeek() == zonedStart.getDayOfWeek())
+                .anyMatch(window -> !openAt.isBefore(window.getOpenTime()) && !closeAt.isAfter(window.getCloseTime()));
+        if (!withinAnyWindow) {
+            throw new AvailabilityViolationException(
+                    "Requested slot is outside the operating hours of resource " + resource.getId());
+        }
+    }
+
+    private void verifyNotBlackedOut(Resource resource, LocalDate from, LocalDate until) {
+        List<BlackoutDate> overlapping = blackouts.findOverlapping(resource.getId(), from, until);
+        if (!overlapping.isEmpty()) {
+            throw new AvailabilityViolationException(
+                    "Resource " + resource.getId() + " is blacked out for the requested date");
+        }
+    }
+}