diff --git a/openapi.yaml b/openapi.yaml
index 2f9675c..4e1d497 100644
--- a/openapi.yaml
+++ b/openapi.yaml
@@ -58,37 +58,8 @@ paths:
         content:
           application/json:
             schema:
-              type: object
-              properties:
-                apiVersion:
-                  type: string
-                kind:
-                  type: string
-                metadata:
-                  type: object
-                  properties:
-                    namespace:
-                      type: string
-                    name:
-                      type: string
-                    title:
-                      type: string
-                    annotations:
-                      type: object
-                  required:
-                    - name
-                  additionalProperties: true
-                spec:
-                  type: object
-                  properties:
-                    owner:
-                      type: string
-                    type:
-                      type: string
-              required:
-                - apiVersion
-                - kind
-                - metadata
+              $ref: "#/components/schemas/Entity"
+
       responses:
         '201':
           description: Created
@@ -283,7 +254,7 @@ paths:
           content:
             application/json:
               schema:
-                type: object
+                $ref: "#/components/schemas/RequestIdResponse"
         '400':
           description: Client failure
           content:
@@ -304,9 +275,85 @@ paths:
         httpMethod: POST
         uri:
           Fn::Sub: "arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${DeleteEntityFunction.Arn}/invocations"
+    put:
+      summary: Delete catalog item
+      description: Delete catalog item
+      parameters:
+        - $ref: "#/components/parameters/namespace"
+        - $ref: "#/components/parameters/kind"
+        - $ref: "#/components/parameters/name"
+        - $ref: "#/components/parameters/headerContentTypeJson"
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/Entity"
+      responses:
+        '200':
+          description: Success
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/RequestIdResponse"
+        '400':
+          description: Client failure
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ErrorResponse"
+        '500':
+          description: Server failure
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ErrorResponse"
+      security:
+        - serverlessOpsCognitoPool:
+          - Fn::Sub: https://${Hostname}/catalog.write
+      x-amazon-apigateway-integration:
+        type: AWS_PROXY
+        httpMethod: POST
+        uri:
+          Fn::Sub: "arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${UpsertEntityFunction.Arn}/invocations"
 
 components:
   schemas:
+    Entity:
+      type: object
+      properties:
+        apiVersion:
+          type: string
+        kind:
+          type: string
+        metadata:
+          type: object
+          properties:
+            namespace:
+              type: string
+            name:
+              type: string
+            title:
+              type: string
+            annotations:
+              type: object
+          required:
+            - name
+          additionalProperties: true
+        spec:
+          type: object
+          properties:
+            owner:
+              type: string
+            type:
+              type: string
+          required:
+            - owner
+          additionalProperties: true
+      required:
+        - apiVersion
+        - kind
+        - metadata
     CreateEntityResponse:
       type: object
       properties:
diff --git a/src/handlers/CreateEntity/function.ts b/src/handlers/CreateEntity/function.ts
index 0cd5b3f..c986106 100644
--- a/src/handlers/CreateEntity/function.ts
+++ b/src/handlers/CreateEntity/function.ts
@@ -31,7 +31,7 @@ interface Item extends Entity {
     itemType: string
 }
 
-export async function putEntity(entity: Entity): Promise<void> {
+export async function putEntity(entity: Entity, upsert: boolean): Promise<void> {
 
     const namespace = entity.metadata.namespace
     const kind = entity.kind.toLowerCase()
@@ -47,7 +47,10 @@ export async function putEntity(entity: Entity): Promise<void> {
     const params: PutItemCommandInput = {
         TableName: DDB_TABLE_NAME,
         Item: marshall(item),
-        ConditionExpression: 'attribute_not_exists(pk) AND attribute_not_exists(sk)'
+    }
+
+    if (!upsert) {
+        params.ConditionExpression = 'attribute_not_exists(pk) AND attribute_not_exists(sk)'
     }
 
     try {
@@ -65,7 +68,7 @@ export async function putEntity(entity: Entity): Promise<void> {
 }
 
 
-export async function handler (event: APIGatewayProxyEvent, context: Context): Promise<APIGatewayProxyResult> {
+export async function handler_create (event: APIGatewayProxyEvent, context: Context): Promise<APIGatewayProxyResult> {
     LOGGER.debug('Received event', { event })
     const event_id = context.awsRequestId
 
@@ -74,7 +77,7 @@ export async function handler (event: APIGatewayProxyEvent, context: Context): P
     let statusCode: number
     let body: string
     try {
-        const output = await putEntity(entity)
+        await putEntity(entity, false)
         statusCode = 201
         body = JSON.stringify({'request_id': event_id})
     } catch (error) {
@@ -99,3 +102,57 @@ export async function handler (event: APIGatewayProxyEvent, context: Context): P
         body
     }
 }
+
+export async function handler_upsert (event: APIGatewayProxyEvent, context: Context): Promise<APIGatewayProxyResult> {
+    LOGGER.debug('Received event', { event })
+    const event_id = context.awsRequestId
+
+    const entity: Entity = JSON.parse(event.body || '{}')   // Already validated body at Gateway
+
+    // Upsert data must match request path
+    const namespace = entity.metadata.namespace
+    const kind = entity.kind.toLowerCase()
+    const name = entity.metadata.name
+
+    if (
+        namespace !== event.pathParameters?.namespace ||
+        kind !== event.pathParameters?.kind ||
+        name !== event.pathParameters?.name
+    ) {
+        return {
+            statusCode: 400,
+            body: JSON.stringify({
+                name: 'BadRequest',
+                message: 'Entity metadata does not match request path'
+            })
+        }
+    }
+
+    let statusCode: number
+    let body: string
+    try {
+        await putEntity(entity, true)
+        statusCode = 201
+        body = JSON.stringify({'request_id': event_id})
+    } catch (error) {
+        LOGGER.error("Operation failed", { event })
+        const fault = (<DynamoDBServiceException>error).$fault
+        switch (fault) {
+            case 'client':
+                statusCode = 400
+                break;
+            default:
+                statusCode = 500
+                break;
+        }
+        body = JSON.stringify({
+            name: (<Error>error).name,
+            message: (<Error>error).message
+        })
+    }
+
+    return {
+        statusCode,
+        body
+    }
+}
\ No newline at end of file
diff --git a/template.yaml b/template.yaml
index 637ec37..a0fc061 100644
--- a/template.yaml
+++ b/template.yaml
@@ -70,7 +70,7 @@ Resources:
     Type: AWS::Serverless::Function
     Properties:
       CodeUri: ./dist/handlers/CreateEntity
-      Handler: function.handler
+      Handler: function.handler_create
       Policies:
         - DynamoDBCrudPolicy:
             TableName: !Ref DdbTable
@@ -95,6 +95,35 @@ Resources:
       Principal: apigateway.amazonaws.com
 
 
+  UpsertEntityFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      CodeUri: ./dist/handlers/UpsertEntity
+      Handler: function.handler_upsert
+      Policies:
+        - DynamoDBCrudPolicy:
+            TableName: !Ref DdbTable
+    Metadata:
+      BuildMethod: esbuild
+      BuildProperties:
+        Minify: true
+        Target: "es2020"
+        Format: "esm"
+        MainFields: module,main # This is to help with ESM modules
+        Sourcemap: !Ref EnableSourceMaps
+        OutExtension:
+          - .js=.mjs
+        EntryPoints:
+          - function.js
+
+  UpsertEntityFunctionInvokePermission:
+    Type: AWS::Lambda::Permission
+    Properties:
+      FunctionName: !GetAtt UpsertEntityFunction.Arn
+      Action: lambda:InvokeFunction
+      Principal: apigateway.amazonaws.com
+
+
   GetEntityFunction:
     Type: AWS::Serverless::Function
     Properties:
@@ -123,6 +152,7 @@ Resources:
       Action: lambda:InvokeFunction
       Principal: apigateway.amazonaws.com
 
+
   DeleteEntityFunction:
     Type: AWS::Serverless::Function
     Properties: