diff --git a/OPENAPI_DOC.yml b/OPENAPI_DOC.yml
index 968b0c4f..7372d00c 100644
--- a/OPENAPI_DOC.yml
+++ b/OPENAPI_DOC.yml
@@ -6390,6 +6390,124 @@ paths:
             application/json:
               schema:
                 $ref: '#/components/schemas/Application__CommonError'
+  /api/staff/v1/events/clashing-assets:
+    post:
+      summary: lists conflicting system_ids based on event time range
+      description: 'lists conflicting system_ids based on event time range
+
+        will return a list of system_ids that are already booked during the specified
+        time range
+
+        if system_ids is set, then it will only return booked systems from that list'
+      tags:
+      - Events
+      operationId: Events_clashing_assets
+      parameters:
+      - name: period_start
+        in: query
+        description: event period start as a unix epoch
+        example: "1661725146"
+        required: true
+        schema:
+          type: integer
+          format: Int64
+      - name: period_end
+        in: query
+        description: event period end as a unix epoch
+        example: "1661743123"
+        required: true
+        schema:
+          type: integer
+          format: Int64
+      - name: system_ids
+        in: query
+        description: comma separated list of system_ids to check for clashes
+        example: sys-1234,sys-5678
+        schema:
+          type: string
+          nullable: true
+      - name: return_available
+        in: query
+        description: return available systems, this requires system_ids be set to
+          the full list
+        example: "false"
+        schema:
+          type: boolean
+      - name: include_clash_time
+        in: query
+        description: include the clash times, this is not compatible with return_available
+        example: "false"
+        schema:
+          type: boolean
+      responses:
+        200:
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/_Array_NamedTuple_system_id__String__event_start__Int64__event_end__Int64_____Array_String__'
+        429:
+          description: Too Many Requests
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Application__CommonError'
+        400:
+          description: Bad Request
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Application__CommonError'
+        401:
+          description: Unauthorized
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Application__CommonError'
+        403:
+          description: Forbidden
+        404:
+          description: Not Found
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Application__CommonError'
+        511:
+          description: Network Authentication Required
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Application__CommonError'
+        406:
+          description: Not Acceptable
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Application__ContentError'
+        415:
+          description: Unsupported Media Type
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Application__ContentError'
+        422:
+          description: Unprocessable Entity
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Application__ValidationError'
+        500:
+          description: Internal Server Error
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Application__CommonError'
+        405:
+          description: Method Not Allowed
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Application__CommonError'
   /api/staff/v1/events/{id}/guests/{guest_id}/check_in:
     post:
       summary: a guest has arrived for a meeting in person.
@@ -13272,6 +13390,8 @@ components:
           type: integer
           format: Int64
           nullable: true
+    _Array_NamedTuple_system_id__String__event_start__Int64__event_end__Int64_____Array_String__:
+      type: array
     PlaceCalendar__Group:
       type: object
       properties:
diff --git a/spec/controllers/bookings_spec.cr b/spec/controllers/bookings_spec.cr
index d2ebb662..bd2d82c1 100644
--- a/spec/controllers/bookings_spec.cr
+++ b/spec/controllers/bookings_spec.cr
@@ -649,7 +649,7 @@ describe Bookings do
       tenant = get_tenant
 
       booking1 = BookingsHelper.create_booking(tenant.id.not_nil!)
-      sleep 1
+      sleep 1.second
       booking2 = BookingsHelper.create_booking(tenant.id.not_nil!)
 
       starting = 5.minutes.from_now.to_unix
@@ -691,7 +691,7 @@ describe Bookings do
         booking_start: 5.minutes.from_now.to_unix,
         booking_end: 35.minutes.from_now.to_unix, asset_id: "desk-2")
 
-      sleep 1
+      sleep 1.second
 
       zones_string = "#{booking1.zones.not_nil!.first},#{booking2.zones.not_nil!.first}"
       route = "#{BOOKINGS_BASE}/booked?period_start=#{starting}&period_end=#{ending}&type=desk&zones=#{zones_string}"
@@ -720,7 +720,7 @@ describe Bookings do
         booking_end: 35.minutes.from_now.to_unix, asset_id: "desk-2")
       client.delete("#{BOOKINGS_BASE}/#{booking2.id}", headers: headers)
 
-      sleep 1
+      sleep 1.second
 
       zones_string = "#{booking1.zones.not_nil!.first},#{booking2.zones.not_nil!.first}"
       route = "#{BOOKINGS_BASE}/booked?period_start=#{starting}&period_end=#{ending}&type=desk&zones=#{zones_string}"
@@ -2120,7 +2120,7 @@ describe Bookings do
     ).status_code
     created.should eq(201)
 
-    sleep 3
+    sleep 3.seconds
 
     client.post("#{BOOKINGS_BASE}/", headers: headers, body: %({"asset_id":"some_desk","booking_start":#{starting},"booking_end":#{ending},"booking_type":"desk","attendees": [
       {
@@ -2156,7 +2156,7 @@ describe Bookings do
     ).status_code
     created.should eq(201)
 
-    sleep 3
+    sleep 3.seconds
 
     client.post("#{BOOKINGS_BASE}/", headers: headers, body: %({"asset_ids":["desk2"],"booking_start":#{starting},"booking_end":#{ending},"booking_type":"desk","attendees": [
       {
@@ -2535,7 +2535,7 @@ describe Bookings do
     booking.checked_out_at = 10.minutes.from_now.to_unix
     booking.save!
 
-    sleep 2
+    sleep 2.seconds
 
     should_create = BookingsHelper.http_create_booking(
       booking_start: 15.minutes.from_now.to_unix,
@@ -2562,7 +2562,7 @@ describe Bookings do
 
     BookingsHelper.create_booking(tenant.id.not_nil!, 15.minutes.from_now.to_unix, 25.minutes.from_now.to_unix, asset_id)
 
-    sleep 2
+    sleep 2.seconds
 
     not_checked_in = client.post("#{BOOKINGS_BASE}/#{booking.id}/check_in", headers: headers).status_code
     not_checked_in.should eq(405)
diff --git a/spec/controllers/events_spec.cr b/spec/controllers/events_spec.cr
index 70ad7d43..c94b6d32 100644
--- a/spec/controllers/events_spec.cr
+++ b/spec/controllers/events_spec.cr
@@ -1336,4 +1336,111 @@ describe Events, tags: ["event"] do
       histories.first.changed_fields.should eq(["ext_data.notes"])
     end
   end
+
+  describe "#clashing_assets" do
+    it "returns clashing system_ids for overlapping events" do
+      tenant = get_tenant
+      event_start = 10.minutes.from_now.to_unix
+      event_end = 30.minutes.from_now.to_unix
+
+      # Create events with different system_ids
+      EventMetadatasHelper.create_event(tenant.id, system_id: "sys-1234", event_start: event_start, event_end: event_end)
+      EventMetadatasHelper.create_event(tenant.id, system_id: "sys-5678", event_start: event_start + 5, event_end: event_end + 5)
+      EventMetadatasHelper.create_event(tenant.id, system_id: "sys-9999", event_start: event_end + 100, event_end: event_end + 200)
+
+      response = client.post(
+        "#{EVENTS_BASE}/clashing-assets?period_start=#{event_start}&period_end=#{event_end}",
+        headers: headers
+      )
+      response.status_code.should eq(200)
+
+      clashing = Array(String).from_json(response.body)
+      clashing.size.should eq(2)
+      clashing.should contain("sys-1234")
+      clashing.should contain("sys-5678")
+      clashing.should_not contain("sys-9999")
+    end
+
+    it "returns only clashing system_ids from provided list" do
+      tenant = get_tenant
+      event_start = 10.minutes.from_now.to_unix
+      event_end = 30.minutes.from_now.to_unix
+
+      EventMetadatasHelper.create_event(tenant.id, system_id: "sys-1234", event_start: event_start, event_end: event_end)
+      EventMetadatasHelper.create_event(tenant.id, system_id: "sys-5678", event_start: event_start, event_end: event_end)
+
+      response = client.post(
+        "#{EVENTS_BASE}/clashing-assets?period_start=#{event_start}&period_end=#{event_end}&system_ids=sys-1234,sys-9999",
+        headers: headers
+      )
+      response.status_code.should eq(200)
+
+      clashing = Array(String).from_json(response.body)
+      clashing.size.should eq(1)
+      clashing.should contain("sys-1234")
+      clashing.should_not contain("sys-5678")
+    end
+
+    it "returns available system_ids when return_available is true" do
+      tenant = get_tenant
+      event_start = 10.minutes.from_now.to_unix
+      event_end = 30.minutes.from_now.to_unix
+
+      EventMetadatasHelper.create_event(tenant.id, system_id: "sys-1234", event_start: event_start, event_end: event_end)
+
+      response = client.post(
+        "#{EVENTS_BASE}/clashing-assets?period_start=#{event_start}&period_end=#{event_end}&system_ids=sys-1234,sys-5678,sys-9999&return_available=true",
+        headers: headers
+      )
+      response.status_code.should eq(200)
+
+      available = Array(String).from_json(response.body)
+      available.size.should eq(2)
+      available.should contain("sys-5678")
+      available.should contain("sys-9999")
+      available.should_not contain("sys-1234")
+    end
+
+    it "returns clash times when include_clash_time is true" do
+      tenant = get_tenant
+      event_start = 10.minutes.from_now.to_unix
+      event_end = 30.minutes.from_now.to_unix
+
+      EventMetadatasHelper.create_event(tenant.id, system_id: "sys-1234", event_start: event_start, event_end: event_end)
+
+      response = client.post(
+        "#{EVENTS_BASE}/clashing-assets?period_start=#{event_start}&period_end=#{event_end}&include_clash_time=true",
+        headers: headers
+      )
+      response.status_code.should eq(200)
+
+      clashing = Array(NamedTuple(system_id: String, event_start: Int64, event_end: Int64)).from_json(response.body)
+      clashing.size.should eq(1)
+      clashing.first[:system_id].should eq("sys-1234")
+      clashing.first[:event_start].should eq(event_start)
+      clashing.first[:event_end].should eq(event_end)
+    end
+
+    it "excludes cancelled events from clashing results" do
+      tenant = get_tenant
+      event_start = 10.minutes.from_now.to_unix
+      event_end = 30.minutes.from_now.to_unix
+
+      EventMetadatasHelper.create_event(tenant.id, system_id: "sys-1234", event_start: event_start, event_end: event_end)
+      cancelled_event = EventMetadatasHelper.create_event(tenant.id, system_id: "sys-5678", event_start: event_start, event_end: event_end)
+      cancelled_event.cancelled = true
+      cancelled_event.save!
+
+      response = client.post(
+        "#{EVENTS_BASE}/clashing-assets?period_start=#{event_start}&period_end=#{event_end}",
+        headers: headers
+      )
+      response.status_code.should eq(200)
+
+      clashing = Array(String).from_json(response.body)
+      clashing.size.should eq(1)
+      clashing.should contain("sys-1234")
+      clashing.should_not contain("sys-5678")
+    end
+  end
 end
diff --git a/spec/controllers/recurring_bookings_spec.cr b/spec/controllers/recurring_bookings_spec.cr
index 8e8a8fd6..3d6c57ca 100644
--- a/spec/controllers/recurring_bookings_spec.cr
+++ b/spec/controllers/recurring_bookings_spec.cr
@@ -17,9 +17,9 @@ describe Bookings do
       tenant = get_tenant
 
       booking1 = BookingsHelper.create_booking(tenant.id.not_nil!)
-      sleep 1
+      sleep 1.second
       booking2 = BookingsHelper.create_booking(tenant.id.not_nil!)
-      sleep 1
+      sleep 1.second
       booking3 = BookingsHelper.create_booking(tenant.id.not_nil!)
 
       booking1.recurrence_type = :daily
diff --git a/spec/controllers/staff_spec.cr b/spec/controllers/staff_spec.cr
index 9c0f369c..088631ca 100644
--- a/spec/controllers/staff_spec.cr
+++ b/spec/controllers/staff_spec.cr
@@ -31,7 +31,7 @@ describe Staff do
 
     WebMock.stub(:post, "https://login.microsoftonline.com/bb89674a-238b-4b7d-91ec-6bebad83553a/oauth2/v2.0/token")
       .to_return(body: File.read("./spec/fixtures/tokens/o365_token.json"))
-    WebMock.stub(:get, "https://graph.microsoft.com/v1.0/users/#{user_id}")
+    WebMock.stub(:get, "https://graph.microsoft.com/v1.0/users/#{user_id}?%24select=id%2CuserPrincipalName%2Csurname%2CpreferredLanguage%2CofficeLocation%2CmobilePhone%2Cmail%2CjobTitle%2CgivenName%2CdisplayName%2CbusinessPhones%2CaccountEnabled%2CmailNickname")
       .to_return(body: File.read("./spec/fixtures/staff/show.json"))
 
     body = PlaceCalendar::User.from_json(client.get("#{STAFF_BASE}/#{user_id}", headers: headers).body)
diff --git a/spec/spec_helper.cr b/spec/spec_helper.cr
index 20759d25..d6858ca1 100644
--- a/spec/spec_helper.cr
+++ b/spec/spec_helper.cr
@@ -26,7 +26,7 @@ Spec.before_suite do
   {% if flag?(:quiet) %}
     ::Log.setup(:warn)
   {% else %}
-    ::Log.setup(:debug)
+    ::Log.setup(:info)
   {% end %}
 end
 
diff --git a/src/controllers/events.cr b/src/controllers/events.cr
index c57c7337..780dd289 100644
--- a/src/controllers/events.cr
+++ b/src/controllers/events.cr
@@ -1739,6 +1739,63 @@ class Events < Application
     query.limit(10_000).to_a
   end
 
+  # lists conflicting system_ids based on event time range
+  # will return a list of system_ids that are already booked during the specified time range
+  # if system_ids is set, then it will only return booked systems from that list
+  @[AC::Route::POST("/clashing-assets")]
+  def clashing_assets(
+    @[AC::Param::Info(name: "period_start", description: "event period start as a unix epoch", example: "1661725146")]
+    starting : Int64,
+    @[AC::Param::Info(name: "period_end", description: "event period end as a unix epoch", example: "1661743123")]
+    ending : Int64,
+    @[AC::Param::Info(description: "comma separated list of system_ids to check for clashes", example: "sys-1234,sys-5678")]
+    system_ids : String? = nil,
+    @[AC::Param::Info(description: "return available systems, this requires system_ids be set to the full list", example: "false")]
+    return_available : Bool = false,
+    @[AC::Param::Info(description: "include the clash times, this is not compatible with return_available", example: "false")]
+    include_clash_time : Bool = false,
+  ) : Array(String) | Array(NamedTuple(system_id: String, event_start: Int64, event_end: Int64))
+    if return_available && system_ids.nil?
+      raise Error::ModelValidation.new([{field: "system_ids".as(String?), reason: "Missing system_ids"}], "error validating event data")
+    end
+
+    if return_available && include_clash_time
+      raise AC::Route::Param::Error.new("include_clash_time and return_available cannot be used together")
+    end
+
+    # Parse system_ids if provided
+    sys_ids = system_ids.try(&.split(',').map(&.strip).reject(&.empty?)) || [] of String
+
+    # Query for clashing events
+    query = EventMetadata
+      .by_tenant(tenant.id)
+      .where("event_end > ? AND event_start < ?", starting, ending)
+      .where("cancelled = ? OR cancelled IS NULL", false)
+
+    # Filter by system_ids if provided
+    query = query.where({:system_id => sys_ids}) unless sys_ids.empty?
+
+    clashing_events = query.to_a
+
+    if include_clash_time
+      result = [] of NamedTuple(system_id: String, event_start: Int64, event_end: Int64)
+      clashing_events.each do |event|
+        if sys_id = event.system_id
+          result << {system_id: sys_id, event_start: event.event_start, event_end: event.event_end}
+        end
+      end
+      result
+    else
+      clashing_system_ids = clashing_events.compact_map(&.system_id).uniq
+
+      if return_available
+        clashing_system_ids = sys_ids - clashing_system_ids
+      end
+
+      clashing_system_ids
+    end
+  end
+
   # a guest has arrived for a meeting in person.
   # This route can be used to notify hosts
   @[AC::Route::POST("/:id/guests/:guest_id/check_in")]