diff --git a/src/main/java/aa/aggregators/institution/openapi.json b/src/main/java/aa/aggregators/institution/openapi.json
new file mode 100644
index 0000000..37c9093
--- /dev/null
+++ b/src/main/java/aa/aggregators/institution/openapi.json
@@ -0,0 +1,193 @@
+{
+  "openapi": "3.0.3",
+  "info": {
+    "title": "Instelling Attributes API",
+    "version": "1.0.0",
+    "description": "API voor het opvragen van attributen op basis van een eduID.\nAuthenticatie gebeurt via HTTP Basic Authentication.\n**Let op:** deze API mag uitsluitend via een beveiligde HTTPS-verbinding worden aangeroepen."
+  },
+  "servers": [
+    {
+      "url": "https://instelling.tld/api",
+      "description": "Productieomgeving (alleen HTTPS toegestaan)"
+    }
+  ],
+  "paths": {
+    "/attributes/{eduid}": {
+      "get": {
+        "summary": "Haal attributen op voor een gebruiker",
+        "description": "Retourneert de attributen die gekoppeld zijn aan het opgegeven eduID.\nAlle velden in de response zijn optioneel.\nVereist HTTP Basic Authentication en HTTPS.",
+        "parameters": [
+          {
+            "name": "eduid",
+            "in": "path",
+            "required": true,
+            "description": "Het eduID van de gebruiker (UUID-formaat).",
+            "schema": {
+              "type": "string",
+              "format": "uuid",
+              "example": "0000-1111-2222-3333"
+            }
+          }
+        ],
+        "security": [
+          {
+            "basicAuth": []
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "Succesvolle respons met attributen (alle velden optioneel).",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/UserAttributes"
+                }
+              }
+            }
+          },
+          "400": {
+            "description": "Ongeldige request, bijvoorbeeld verkeerd UUID-formaat.",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/ErrorResponse"
+                },
+                "example": {
+                  "error": "Invalid eduID format"
+                }
+              }
+            }
+          },
+          "404": {
+            "description": "Gebruiker niet gevonden voor het opgegeven eduID.",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/ErrorResponse"
+                },
+                "example": {
+                  "error": "User not found"
+                }
+              }
+            }
+          },
+          "401": {
+            "description": "Authenticatie vereist of ongeldig.",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/ErrorResponse"
+                },
+                "example": {
+                  "error": "Unauthorized"
+                }
+              }
+            }
+          },
+          "500": {
+            "description": "Interne serverfout.",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/ErrorResponse"
+                },
+                "example": {
+                  "error": "Internal server error"
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  },
+  "components": {
+    "securitySchemes": {
+      "basicAuth": {
+        "type": "http",
+        "scheme": "basic"
+      }
+    },
+    "schemas": {
+      "AttributeArray": {
+        "type": "array",
+        "items": {
+          "type": "string"
+        }
+      },
+      "UserAttributes": {
+        "type": "object",
+        "description": "Bevat alle mogelijke attributen van een gebruiker. Alle velden zijn optioneel; afwezigheid betekent dat het attribuut niet bekend is.",
+        "properties": {
+          "given_name": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["John"]
+          },
+          "family_name": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["Doe"]
+          },
+          "name": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["Prof.dr. John Doe"]
+          },
+          "email": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["john.doe@example.com"]
+          },
+          "ou": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["Faculty of Science"]
+          },
+          "schac_home_organization": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["university.nl"]
+          },
+          "eduperson_scoped_affiliation": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["student@uniharderwijk.nl"]
+          },
+          "uids": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["jdoe123"]
+          },
+          "schac_personal_unique_code": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["S12345678"]
+          },
+          "eduperson_principal_name": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["johndoe@studenthartingcollege.nl"]
+          },
+          "eduperson_entitlement": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["urn:x-surfnet:surf.nl:surfdrive:quota:100"]
+          },
+          "edumember_is_member_of": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["research-group"]
+          },
+          "eckid": {
+            "$ref": "#/components/schemas/AttributeArray",
+            "example": ["eck123456"]
+          }
+        }
+      },
+      "ErrorResponse": {
+        "type": "object",
+        "properties": {
+          "error": {
+            "type": "string",
+            "description": "Beschrijving van de foutmelding"
+          }
+        },
+        "required": ["error"]
+      }
+    }
+  },
+  "security": [
+    {
+      "basicAuth": []
+    }
+  ]
+}
diff --git a/src/main/java/aa/aggregators/institution/openapi.yaml b/src/main/java/aa/aggregators/institution/openapi.yaml
new file mode 100644
index 0000000..9c9aa21
--- /dev/null
+++ b/src/main/java/aa/aggregators/institution/openapi.yaml
@@ -0,0 +1,134 @@
+openapi: 3.0.3
+info:
+  title: Instelling Attributes API
+  version: 1.0.0
+  description: |
+    API voor het opvragen van attributen op basis van een eduID.
+    Authenticatie gebeurt via HTTP Basic Authentication.
+    **Let op:** deze API mag uitsluitend via een beveiligde HTTPS-verbinding worden aangeroepen.
+servers:
+  - url: https://instelling.tld/api
+    description: Productieomgeving (alleen HTTPS toegestaan)
+paths:
+  /attributes/{eduid}:
+    get:
+      summary: Haal attributen op voor een gebruiker
+      description: |
+        Retourneert de attributen die gekoppeld zijn aan het opgegeven eduID.
+        Alle velden in de response zijn optioneel.
+        Vereist HTTP Basic Authentication en HTTPS.
+      parameters:
+        - name: eduid
+          in: path
+          required: true
+          description: Het eduID van de gebruiker (UUID-formaat).
+          schema:
+            type: string
+            format: uuid
+            example: 0000-1111-2222-3333
+      security:
+        - basicAuth: []
+      responses:
+        '200':
+          description: Succesvolle respons met attributen (alle velden optioneel).
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/UserAttributes'
+        '400':
+          description: Ongeldige request, bijvoorbeeld verkeerd UUID-formaat.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorResponse'
+              example:
+                error: "Invalid eduID format"
+        '404':
+          description: Gebruiker niet gevonden voor het opgegeven eduID.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorResponse'
+              example:
+                error: "User not found"
+        '401':
+          description: Authenticatie vereist of ongeldig.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorResponse'
+              example:
+                error: "Unauthorized"
+        '500':
+          description: Interne serverfout.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ErrorResponse'
+              example:
+                error: "Internal server error"
+components:
+  securitySchemes:
+    basicAuth:
+      type: http
+      scheme: basic
+  schemas:
+    AttributeArray:
+      type: array
+      items:
+        type: string
+    UserAttributes:
+      type: object
+      description: |
+        Bevat alle mogelijke attributen van een gebruiker.
+        Alle velden zijn optioneel; afwezigheid betekent dat het attribuut niet bekend is.
+      properties:
+        given_name:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["John"]
+        family_name:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["Doe"]
+        name:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["Prof.dr. John Doe"]
+        email:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["john.doe@example.com"]
+        ou:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["Faculty of Science"]
+        schac_home_organization:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["university.nl"]
+        eduperson_scoped_affiliation:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["student@uniharderwijk.nl"]
+        uids:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["jdoe123"]
+        schac_personal_unique_code:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["S12345678"]
+        eduperson_principal_name:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["johndoe@studenthartingcollege.nl"]
+        eduperson_entitlement:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["urn:x-surfnet:surf.nl:surfdrive:quota:100"]
+        edumember_is_member_of:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["research-group"]
+        eckid:
+          $ref: '#/components/schemas/AttributeArray'
+          example: ["eck123456"]
+    ErrorResponse:
+      type: object
+      properties:
+        error:
+          type: string
+          description: Beschrijving van de foutmelding
+      required:
+        - error
+security:
+  - basicAuth: []