diff --git a/.vscode/launch.json b/.vscode/launch.json
index c3e92a3..9c231b9 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -21,7 +21,7 @@
             "type": "chrome",
             "request": "launch",
             "name": "Launch Chrome",
-            "url": "http://localhost:8080/nodes",
+            "url": "http://localhost:8080/api-docs-test",
             "webRoot": "${workspaceFolder}"
         },
         {

diff --git a/.vscode/launch.json b/.vscode/launch.json
index c3e92a3..9c231b9 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -21,7 +21,7 @@
             "type": "chrome",
             "request": "launch",
             "name": "Launch Chrome",
-            "url": "http://localhost:8080/nodes",
+            "url": "http://localhost:8080/api-docs-test",
             "webRoot": "${workspaceFolder}"
         },
         {
diff --git a/src/OpenApiGenerator.ts b/src/OpenApiGenerator.ts
new file mode 100644
index 0000000..573eb69
--- /dev/null
+++ b/src/OpenApiGenerator.ts
@@ -0,0 +1,113 @@
+import { OpenAPIV3 } from "openapi-types";
+import { Description } from "./app";
+import { Collection, Entity, Property } from "./MySchema";
+
+type APISchemas = {
+    [key: string]: OpenAPIV3.ReferenceObject | OpenAPIV3.ArraySchemaObject | OpenAPIV3.NonArraySchemaObject;
+};
+
+function generateSchemas(entities: Entity[]): APISchemas {
+    return fromEntites(entities.map(generateSchema));
+}
+
+function generateSchema(entity: Entity): [string, OpenAPIV3.NonArraySchemaObject] {
+    const schema: OpenAPIV3.NonArraySchemaObject = {
+        type: "object",
+        required: entity.properties.filter(p => !p.isNullable).map(p => p.key).concat(["id", "ref"]),
+        properties: fromEntites(addIdProperties(entity.properties.map(generateProperty))),
+    };
+    return [
+        entity.name,
+        schema,
+    ];
+}
+
+function addIdProperties(properties: [string, OpenAPIV3.NonArraySchemaObject][]): [string, OpenAPIV3.NonArraySchemaObject][] {
+    return [
+        ["id", { type: "number", format: "int32" }],
+        ...properties,
+        ["ref", { type: "string", format: "uri" }],
+    ];
+}
+
+function fromEntites<T>(list: [string, T][]): { [key: string]: T; } {
+    const obj: { [key: string]: T; } = {};
+    for (const mapped of list) {
+        obj[mapped[0]] = mapped[1];
+    }
+    return obj;
+}
+
+function generateProperty(property: Property): [string, OpenAPIV3.NonArraySchemaObject] {
+    const prop: OpenAPIV3.NonArraySchemaObject = {
+        type: property.type,
+    }
+    return [
+        property.key,
+        prop,
+    ];
+}
+
+function generatePaths(collections: Collection[]): OpenAPIV3.PathsObject {
+    return fromEntites(collections.map(generateCollectionPath));
+}
+
+function generateCollectionPath(collection: Collection): [string, OpenAPIV3.PathItemObject] {
+    const route: string = "/" + collection.name.toLowerCase();
+    const path: OpenAPIV3.PathItemObject = {
+        get: generateGetAllOperation(collection),
+    };
+    return [route, path];
+}
+
+function generateGetAllOperation(collection: Collection): OpenAPIV3.OperationObject {
+    const operation: OpenAPIV3.OperationObject = {
+        responses: {
+            "200": {
+                description: `Lists all ${collection.name}`,
+                content: {
+                    "application/json": {
+                        schema: {
+                            type: "array",
+                            items: {
+                                $ref: "#/components/schemas/" + collection.entities.name
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    };
+    return operation;
+}
+
+const NotFoundResponse: OpenAPIV3.ResponseObject = {
+    description: "The specified resource does not exist.",
+    content: {
+        "text/plain": {
+            schema: {
+                type: "string",
+                example: "not found",
+            }
+        }
+    }
+};
+
+export function generateOpenAPI(description: Description): OpenAPIV3.Document {
+    const doc: OpenAPIV3.Document = {
+        openapi: "3.0.0",
+        info: {
+            title: "API for " + description.collections.map(c => c.name).join(", "),
+            version: "1.0.0",
+        },
+        servers: [{ url: "http://localhost:8080" }],
+        components: {
+            schemas: generateSchemas(description.collections.map(c => c.entities)),
+            responses: {
+                NotFound: NotFoundResponse
+            }
+        },
+        paths: generatePaths(description.collections),
+    };
+    return doc;
+}

diff --git a/.vscode/launch.json b/.vscode/launch.json
index c3e92a3..9c231b9 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -21,7 +21,7 @@
             "type": "chrome",
             "request": "launch",
             "name": "Launch Chrome",
-            "url": "http://localhost:8080/nodes",
+            "url": "http://localhost:8080/api-docs-test",
             "webRoot": "${workspaceFolder}"
         },
         {
diff --git a/src/OpenApiGenerator.ts b/src/OpenApiGenerator.ts
new file mode 100644
index 0000000..573eb69
--- /dev/null
+++ b/src/OpenApiGenerator.ts
@@ -0,0 +1,113 @@
+import { OpenAPIV3 } from "openapi-types";
+import { Description } from "./app";
+import { Collection, Entity, Property } from "./MySchema";
+
+type APISchemas = {
+    [key: string]: OpenAPIV3.ReferenceObject | OpenAPIV3.ArraySchemaObject | OpenAPIV3.NonArraySchemaObject;
+};
+
+function generateSchemas(entities: Entity[]): APISchemas {
+    return fromEntites(entities.map(generateSchema));
+}
+
+function generateSchema(entity: Entity): [string, OpenAPIV3.NonArraySchemaObject] {
+    const schema: OpenAPIV3.NonArraySchemaObject = {
+        type: "object",
+        required: entity.properties.filter(p => !p.isNullable).map(p => p.key).concat(["id", "ref"]),
+        properties: fromEntites(addIdProperties(entity.properties.map(generateProperty))),
+    };
+    return [
+        entity.name,
+        schema,
+    ];
+}
+
+function addIdProperties(properties: [string, OpenAPIV3.NonArraySchemaObject][]): [string, OpenAPIV3.NonArraySchemaObject][] {
+    return [
+        ["id", { type: "number", format: "int32" }],
+        ...properties,
+        ["ref", { type: "string", format: "uri" }],
+    ];
+}
+
+function fromEntites<T>(list: [string, T][]): { [key: string]: T; } {
+    const obj: { [key: string]: T; } = {};
+    for (const mapped of list) {
+        obj[mapped[0]] = mapped[1];
+    }
+    return obj;
+}
+
+function generateProperty(property: Property): [string, OpenAPIV3.NonArraySchemaObject] {
+    const prop: OpenAPIV3.NonArraySchemaObject = {
+        type: property.type,
+    }
+    return [
+        property.key,
+        prop,
+    ];
+}
+
+function generatePaths(collections: Collection[]): OpenAPIV3.PathsObject {
+    return fromEntites(collections.map(generateCollectionPath));
+}
+
+function generateCollectionPath(collection: Collection): [string, OpenAPIV3.PathItemObject] {
+    const route: string = "/" + collection.name.toLowerCase();
+    const path: OpenAPIV3.PathItemObject = {
+        get: generateGetAllOperation(collection),
+    };
+    return [route, path];
+}
+
+function generateGetAllOperation(collection: Collection): OpenAPIV3.OperationObject {
+    const operation: OpenAPIV3.OperationObject = {
+        responses: {
+            "200": {
+                description: `Lists all ${collection.name}`,
+                content: {
+                    "application/json": {
+                        schema: {
+                            type: "array",
+                            items: {
+                                $ref: "#/components/schemas/" + collection.entities.name
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    };
+    return operation;
+}
+
+const NotFoundResponse: OpenAPIV3.ResponseObject = {
+    description: "The specified resource does not exist.",
+    content: {
+        "text/plain": {
+            schema: {
+                type: "string",
+                example: "not found",
+            }
+        }
+    }
+};
+
+export function generateOpenAPI(description: Description): OpenAPIV3.Document {
+    const doc: OpenAPIV3.Document = {
+        openapi: "3.0.0",
+        info: {
+            title: "API for " + description.collections.map(c => c.name).join(", "),
+            version: "1.0.0",
+        },
+        servers: [{ url: "http://localhost:8080" }],
+        components: {
+            schemas: generateSchemas(description.collections.map(c => c.entities)),
+            responses: {
+                NotFound: NotFoundResponse
+            }
+        },
+        paths: generatePaths(description.collections),
+    };
+    return doc;
+}
diff --git a/src/app.ts b/src/app.ts
index dcdb3b4..1d57731 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -3,6 +3,7 @@
 import * as fs from "fs";
 import { generateModel } from "./ModelGenerator";
 import { generateDataAccess } from "./DataAccessGenerator";
+import { generateOpenAPI } from "./OpenApiGenerator";
 
 interface Options {
     typeScriptOutputFolder: string;
@@ -33,20 +34,32 @@
     }
 }
 
+/**
+ * Central function, that contains all the (pure) logic.
+ * @param options parameters for the generators
+ * @param description The supplied data model description
+ */
 function generate(options: Options, description: Description): FileWrite[] {
     // generate model files
     const modelWrites = generateModel(description.collections);
-    modelWrites.forEach(w => {w.location = join(options.typeScriptOutputFolder, w.location)})
+    modelWrites.forEach(w => { w.location = join(options.typeScriptOutputFolder, w.location) })
 
     // generate data access files
     const dataAccessWrites = generateDataAccess(description.collections);
-    dataAccessWrites.forEach(w => {w.location = join(options.typeScriptOutputFolder, w.location)})
+    dataAccessWrites.forEach(w => { w.location = join(options.typeScriptOutputFolder, w.location) })
+
+    // generate openapi file
+    const openapiDoc = generateOpenAPI(description);
+    const openapiWrites: FileWrite = { location: options.openapiOutput, content: JSON.stringify(openapiDoc, null, "\t") };
 
     // generate middleware file
-    // generate openapi file
-    //  -> see https://swagger.io/docs/specification/describing-responses/
 
-    return [...modelWrites, ...dataAccessWrites];
+
+    return [
+        ...modelWrites,
+        ...dataAccessWrites,
+        openapiWrites,
+    ];
 }
 
 function execute() {

diff --git a/.vscode/launch.json b/.vscode/launch.json
index c3e92a3..9c231b9 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -21,7 +21,7 @@
             "type": "chrome",
             "request": "launch",
             "name": "Launch Chrome",
-            "url": "http://localhost:8080/nodes",
+            "url": "http://localhost:8080/api-docs-test",
             "webRoot": "${workspaceFolder}"
         },
         {
diff --git a/src/OpenApiGenerator.ts b/src/OpenApiGenerator.ts
new file mode 100644
index 0000000..573eb69
--- /dev/null
+++ b/src/OpenApiGenerator.ts
@@ -0,0 +1,113 @@
+import { OpenAPIV3 } from "openapi-types";
+import { Description } from "./app";
+import { Collection, Entity, Property } from "./MySchema";
+
+type APISchemas = {
+    [key: string]: OpenAPIV3.ReferenceObject | OpenAPIV3.ArraySchemaObject | OpenAPIV3.NonArraySchemaObject;
+};
+
+function generateSchemas(entities: Entity[]): APISchemas {
+    return fromEntites(entities.map(generateSchema));
+}
+
+function generateSchema(entity: Entity): [string, OpenAPIV3.NonArraySchemaObject] {
+    const schema: OpenAPIV3.NonArraySchemaObject = {
+        type: "object",
+        required: entity.properties.filter(p => !p.isNullable).map(p => p.key).concat(["id", "ref"]),
+        properties: fromEntites(addIdProperties(entity.properties.map(generateProperty))),
+    };
+    return [
+        entity.name,
+        schema,
+    ];
+}
+
+function addIdProperties(properties: [string, OpenAPIV3.NonArraySchemaObject][]): [string, OpenAPIV3.NonArraySchemaObject][] {
+    return [
+        ["id", { type: "number", format: "int32" }],
+        ...properties,
+        ["ref", { type: "string", format: "uri" }],
+    ];
+}
+
+function fromEntites<T>(list: [string, T][]): { [key: string]: T; } {
+    const obj: { [key: string]: T; } = {};
+    for (const mapped of list) {
+        obj[mapped[0]] = mapped[1];
+    }
+    return obj;
+}
+
+function generateProperty(property: Property): [string, OpenAPIV3.NonArraySchemaObject] {
+    const prop: OpenAPIV3.NonArraySchemaObject = {
+        type: property.type,
+    }
+    return [
+        property.key,
+        prop,
+    ];
+}
+
+function generatePaths(collections: Collection[]): OpenAPIV3.PathsObject {
+    return fromEntites(collections.map(generateCollectionPath));
+}
+
+function generateCollectionPath(collection: Collection): [string, OpenAPIV3.PathItemObject] {
+    const route: string = "/" + collection.name.toLowerCase();
+    const path: OpenAPIV3.PathItemObject = {
+        get: generateGetAllOperation(collection),
+    };
+    return [route, path];
+}
+
+function generateGetAllOperation(collection: Collection): OpenAPIV3.OperationObject {
+    const operation: OpenAPIV3.OperationObject = {
+        responses: {
+            "200": {
+                description: `Lists all ${collection.name}`,
+                content: {
+                    "application/json": {
+                        schema: {
+                            type: "array",
+                            items: {
+                                $ref: "#/components/schemas/" + collection.entities.name
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    };
+    return operation;
+}
+
+const NotFoundResponse: OpenAPIV3.ResponseObject = {
+    description: "The specified resource does not exist.",
+    content: {
+        "text/plain": {
+            schema: {
+                type: "string",
+                example: "not found",
+            }
+        }
+    }
+};
+
+export function generateOpenAPI(description: Description): OpenAPIV3.Document {
+    const doc: OpenAPIV3.Document = {
+        openapi: "3.0.0",
+        info: {
+            title: "API for " + description.collections.map(c => c.name).join(", "),
+            version: "1.0.0",
+        },
+        servers: [{ url: "http://localhost:8080" }],
+        components: {
+            schemas: generateSchemas(description.collections.map(c => c.entities)),
+            responses: {
+                NotFound: NotFoundResponse
+            }
+        },
+        paths: generatePaths(description.collections),
+    };
+    return doc;
+}
diff --git a/src/app.ts b/src/app.ts
index dcdb3b4..1d57731 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -3,6 +3,7 @@
 import * as fs from "fs";
 import { generateModel } from "./ModelGenerator";
 import { generateDataAccess } from "./DataAccessGenerator";
+import { generateOpenAPI } from "./OpenApiGenerator";
 
 interface Options {
     typeScriptOutputFolder: string;
@@ -33,20 +34,32 @@
     }
 }
 
+/**
+ * Central function, that contains all the (pure) logic.
+ * @param options parameters for the generators
+ * @param description The supplied data model description
+ */
 function generate(options: Options, description: Description): FileWrite[] {
     // generate model files
     const modelWrites = generateModel(description.collections);
-    modelWrites.forEach(w => {w.location = join(options.typeScriptOutputFolder, w.location)})
+    modelWrites.forEach(w => { w.location = join(options.typeScriptOutputFolder, w.location) })
 
     // generate data access files
     const dataAccessWrites = generateDataAccess(description.collections);
-    dataAccessWrites.forEach(w => {w.location = join(options.typeScriptOutputFolder, w.location)})
+    dataAccessWrites.forEach(w => { w.location = join(options.typeScriptOutputFolder, w.location) })
+
+    // generate openapi file
+    const openapiDoc = generateOpenAPI(description);
+    const openapiWrites: FileWrite = { location: options.openapiOutput, content: JSON.stringify(openapiDoc, null, "\t") };
 
     // generate middleware file
-    // generate openapi file
-    //  -> see https://swagger.io/docs/specification/describing-responses/
 
-    return [...modelWrites, ...dataAccessWrites];
+
+    return [
+        ...modelWrites,
+        ...dataAccessWrites,
+        openapiWrites,
+    ];
 }
 
 function execute() {
diff --git a/src/server.ts b/src/server.ts
index d70107d..3813ce8 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -14,8 +14,10 @@
 
 import * as swaggerUi from "swagger-ui-express";
 import * as swaggerDocument from "./ExampleOutput/openapi.json";
+import * as swaggerDocumentTest from "./TestOutput/openapi.json";
 
 app.use('/api-docs', swaggerUi.serve, swaggerUi.setup(swaggerDocument));
+app.use('/api-docs-test', swaggerUi.serve, swaggerUi.setup(swaggerDocumentTest));
 
 app.get(`${webRoot}${INDEX_ROUTE}`, (req, res) => {
     res.send("Hello there :-)");