diff --git a/docs/openapi.json b/docs/openapi.json
index 4dd54c7e..1a4edfd3 100644
--- a/docs/openapi.json
+++ b/docs/openapi.json
@@ -145,6 +145,77 @@
         "summary": "Creates a new yadage workflow."
       }
     },
+    "/api/analyses/{analysis_id}/workspace": {
+      "post": {
+        "consumes": [
+          "multipart/form-data"
+        ],
+        "description": "This resource expects a file to be placed in the analysis workspace identified by the UUID `analysis_id`.",
+        "operationId": "seed_analysis",
+        "parameters": [
+          {
+            "description": "Required. Organization which the analysis belongs to.",
+            "in": "query",
+            "name": "organization",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "description": "Required. UUID of analysis owner.",
+            "in": "query",
+            "name": "user",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "description": "Required. Analysis UUID.",
+            "in": "path",
+            "name": "analysis_id",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "description": "Required. File to be transferred to the analysis workspace.",
+            "in": "formData",
+            "name": "file_content",
+            "required": true,
+            "type": "file"
+          },
+          {
+            "description": "Required. File name.",
+            "in": "query",
+            "name": "file_name",
+            "required": true,
+            "type": "string"
+          }
+        ],
+        "produces": [
+          "application/json"
+        ],
+        "responses": {
+          "200": {
+            "description": "Request succeeded. File successfully trasferred.",
+            "examples": {
+              "application/json": {
+                "message": "File successfully transferred"
+              }
+            },
+            "schema": {
+              "properties": {
+                "message": {
+                  "type": "string"
+                }
+              },
+              "type": "object"
+            }
+          },
+          "400": {
+            "description": "Request failed. The incoming data specification seems malformed"
+          }
+        },
+        "summary": "Seeds the analysis workspace with the provided file."
+      }
+    },
     "/api/ping": {
       "get": {
         "description": "Ping the server.",
diff --git a/reana_server/api_client.py b/reana_server/api_client.py
index 594e9482..d671ff95 100644
--- a/reana_server/api_client.py
+++ b/reana_server/api_client.py
@@ -46,7 +46,9 @@ def create_openapi_client(component):
     try:
         address, spec_file = COMPONENTS_DATA[component]
         json_spec = get_spec(spec_file)
-        client = SwaggerClient.from_spec(json_spec)
+        client = SwaggerClient.from_spec(
+            json_spec,
+            config={'also_return_response': True})
         client.swagger_spec.api_url = address
         return client
     except KeyError:
diff --git a/reana_server/openapi_connections/reana_workflow_controller.json b/reana_server/openapi_connections/reana_workflow_controller.json
index e8671a5d..42b2a801 100644
--- a/reana_server/openapi_connections/reana_workflow_controller.json
+++ b/reana_server/openapi_connections/reana_workflow_controller.json
@@ -97,6 +97,81 @@
         "summary": "Returns all workflows."
       }
     },
+    "/api/workflows/{workflow_id}/workspace": {
+      "post": {
+        "consumes": [
+          "multipart/form-data"
+        ],
+        "description": "This resource is expecting a workflow UUID and a file to place in the workflow workspace.",
+        "operationId": "seed_workflow",
+        "parameters": [
+          {
+            "description": "Required. Organization which the worklow belongs to.",
+            "in": "query",
+            "name": "organization",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "description": "Required. UUID of workflow owner.",
+            "in": "query",
+            "name": "user",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "description": "Required. Workflow UUID.",
+            "in": "path",
+            "name": "workflow_id",
+            "required": true,
+            "type": "string"
+          },
+          {
+            "description": "Required. File to add to the workflow workspace.",
+            "in": "formData",
+            "name": "file_content",
+            "required": true,
+            "type": "file"
+          },
+          {
+            "description": "Required. File name.",
+            "in": "query",
+            "name": "file_name",
+            "required": true,
+            "type": "string"
+          }
+        ],
+        "produces": [
+          "application/json"
+        ],
+        "responses": {
+          "200": {
+            "description": "Request succeeded. The file has been added to the workspace.",
+            "examples": {
+              "application/json": {
+                "message": "Workflow has been added to the workspace",
+                "workflow_id": "cdcf48b1-c2f3-4693-8230-b066e088c6ac"
+              }
+            },
+            "schema": {
+              "properties": {
+                "message": {
+                  "type": "string"
+                },
+                "workflow_id": {
+                  "type": "string"
+                }
+              },
+              "type": "object"
+            }
+          },
+          "400": {
+            "description": "Request failed. The incoming data specification seems malformed"
+          }
+        },
+        "summary": "Adds a file to the workflow workspace."
+      }
+    },
     "/api/yadage/remote": {
       "post": {
         "consumes": [
diff --git a/reana_server/rest/analyses.py b/reana_server/rest/analyses.py
index d1b6a030..e79adec4 100644
--- a/reana_server/rest/analyses.py
+++ b/reana_server/rest/analyses.py
@@ -21,8 +21,6 @@
 
 """Reana-Server Ping-functionality Flask-Blueprint."""
 
-import json
-
 from flask import current_app as app
 from flask import Blueprint, jsonify, request
 
@@ -98,10 +96,10 @@ def get_analyses():  # noqa
               }
     """
     try:
-        res = rwc_api_client.api.get_workflows(
+        response, status_code = rwc_api_client.api.get_workflows(
             organization='default',
             user='00000000-0000-0000-0000-000000000000').result()
-        return jsonify(res), 200
+        return jsonify(response), status_code
     except Exception as e:
         return jsonify({"message": str(e)}), 500
 
@@ -169,8 +167,8 @@ def create_analysis():  # noqa
     try:
         if request.json:
             # validate against schema
-            reana_spec_file = request.json
-            workflow_engine = reana_spec_file['workflow']['type']
+            reana_spec = request.json
+            workflow_engine = reana_spec['workflow']['type']
         elif request.args.get('spec'):
             # TODO implement load workflow engine from remote
             return jsonify('Not implemented'), 501
@@ -182,17 +180,94 @@ def create_analysis():  # noqa
             raise Exception('Unknown workflow engine')
 
         if workflow_engine == 'yadage':
-            if 'reana_spec_file' in locals():
+            if 'reana_spec' in locals():
                 # From spec file
-                res = rwc_api_client.api.run_yadage_workflow_from_spec(
-                    workflow={
-                        'parameters': reana_spec_file['parameters'],
-                        'workflow_spec': reana_spec_file['workflow']['spec'],
-                    },
-                    user=request.args.get('user'),
-                    organization=request.args.get('organization')).result()
-
-            return jsonify(res), 200
+                (response, status_code) = \
+                    rwc_api_client.api.run_yadage_workflow_from_spec(
+                        workflow={
+                            'parameters': reana_spec['parameters'],
+                            'workflow_spec': reana_spec['workflow']['spec'],
+                        },
+                        user=request.args.get('user'),
+                        organization=request.args.get('organization')).result()
+
+            return jsonify(response), status_code
+    except KeyError as e:
+        return jsonify({"message": str(e)}), 400
+    except Exception as e:
+        return jsonify({"message": str(e)}), 500
+
+
+@blueprint.route('/analyses/<analysis_id>/workspace', methods=['POST'])
+def seed_analysis(analysis_id):  # noqa
+    r"""Seed analysis with files.
+
+    ---
+    post:
+      summary: Seeds the analysis workspace with the provided file.
+      description: >-
+        This resource expects a file to be placed in the analysis workspace
+        identified by the UUID `analysis_id`.
+      operationId: seed_analysis
+      consumes:
+        - multipart/form-data
+      produces:
+        - application/json
+      parameters:
+        - name: organization
+          in: query
+          description: Required. Organization which the analysis belongs to.
+          required: true
+          type: string
+        - name: user
+          in: query
+          description: Required. UUID of analysis owner.
+          required: true
+          type: string
+        - name: analysis_id
+          in: path
+          description: Required. Analysis UUID.
+          required: true
+          type: string
+        - name: file_content
+          in: formData
+          description: >-
+            Required. File to be transferred to the analysis workspace.
+          required: true
+          type: file
+        - name: file_name
+          in: query
+          description: Required. File name.
+          required: true
+          type: string
+      responses:
+        200:
+          description: >-
+            Request succeeded. File successfully trasferred.
+          schema:
+            type: object
+            properties:
+              message:
+                type: string
+          examples:
+            application/json:
+              {
+                "message": "File successfully transferred",
+              }
+        400:
+          description: >-
+            Request failed. The incoming data specification seems malformed
+    """
+    try:
+        file_ = request.files['file_content'].stream.read()
+        response, status_code = rwc_api_client.api.seed_workflow(
+            user=request.args['user'],
+            organization=request.args['organization'],
+            workflow_id=analysis_id,
+            file_content=file_,
+            file_name=request.args['file_name']).result()
+
+        return jsonify(response), status_code
     except KeyError as e:
         return jsonify({"message": str(e)}), 400
     except Exception as e: