diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 000000000000..e0ae80ab1858
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,97 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "CVAT Server",
+            "type": "python",
+            "request": "launch",
+            "stopOnEntry": false,
+            "pythonPath": "${config:python.pythonPath}",
+            "program": "${workspaceRoot}/manage.py",
+            "args": [
+                "runserver",
+                "--noreload",
+                "--nothreading",
+                "--insecure",
+                "127.0.0.1:7000"
+            ],
+            "debugOptions": [
+                "RedirectOutput",
+                "DjangoDebugging"
+            ],
+            "cwd": "${workspaceFolder}",
+            "env": {},
+            "envFile": "${workspaceFolder}/.env",
+        },
+        {
+            "name": "CVAT Client",
+            "type": "chrome",
+            "request": "launch",
+            "url": "http://localhost:7000/",
+            "disableNetworkCache":true,
+            "trace": true,
+            "showAsyncStacks": true,
+            "pathMapping":{
+                "/static/engine/": "${workspaceFolder}/cvat/apps/engine/static/engine/",
+                "/static/dashboard/": "${workspaceFolder}/cvat/apps/dashboard/static/dashboard/",
+            }
+        },
+        {
+            "name": "CVAT RQ - default",
+            "type": "python",
+            "request": "launch",
+            "stopOnEntry": false,
+            "pythonPath": "${config:python.pythonPath}",
+            "program": "${workspaceRoot}/manage.py",
+            "args": [
+                "rqworker",
+                "default",
+                "--worker-class",
+                "cvat.simpleworker.SimpleWorker",
+            ],
+            "debugOptions": [
+                "RedirectOutput",
+                "DjangoDebugging"
+            ],
+            "cwd": "${workspaceFolder}",
+            "env": {},
+            "envFile": "${workspaceFolder}/.env",
+
+        },
+        {
+            "name": "CVAT RQ - low",
+            "type": "python",
+            "request": "launch",
+            "stopOnEntry": false,
+            "pythonPath": "${config:python.pythonPath}",
+            "program": "${workspaceRoot}/manage.py",
+            "args": [
+                "rqworker",
+                "low",
+                "--worker-class",
+                "cvat.simpleworker.SimpleWorker",
+            ],
+            "debugOptions": [
+                "RedirectOutput",
+                "DjangoDebugging"
+            ],
+            "cwd": "${workspaceFolder}",
+            "env": {},
+            "envFile": "${workspaceFolder}/.env",
+        },
+    ],
+    "compounds": [
+        {
+            "name": "CVAT Debugging",
+            "configurations": [
+                "CVAT Client",
+                "CVAT Server",
+                "CVAT RQ - default",
+                "CVAT RQ - low",
+            ]
+        }
+    ]
+}
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 356157809027..d3776747e461 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -2,3 +2,52 @@
 
 When contributing to this repository, please first discuss the change you wish to make via issue,
 email, or any other method with the owners of this repository before making a change.
+
+## Development environment
+
+Next steps should work on clear Ubuntu 18.04.
+
+- Install necessary dependencies:
+
+```sh
+$ sudo apt-get install -y curl redis-server python3-dev python3-pip python3-venv libldap2-dev libsasl2-dev
+```
+
+- Install [Visual Studio Code](https://code.visualstudio.com/docs/setup/linux#_debian-and-ubuntu-based-distributions) for development
+
+- Install CVAT on your local host:
+
+```sh
+$ git clone https://github.com/opencv/cvat
+$ cd cvat && mkdir logs keys
+$ python3 -m venv .env
+$ . .env/bin/activate
+$ pip install -U pip wheel
+$ pip install -r cvat/requirements/development.txt
+$ python manage.py migrate
+$ python manage.py collectstatic
+```
+
+- Create a super user for CVAT:
+
+```sh
+$ python manage.py createsuperuser
+Username (leave blank to use 'django'): ***
+Email address: ***
+Password: ***
+Password (again): ***
+```
+
+- Run Visual Studio Code from the virtual environment
+
+```
+$ code .
+```
+
+- Inside Visual Studio Code install [Debugger for Chrome](https://marketplace.visualstudio.com/items?itemName=msjsdiag.debugger-for-chrome) and [Python](https://marketplace.visualstudio.com/items?itemName=ms-python.python) extensions
+
+- Reload Visual Studio Code
+
+- Select `CVAT Debugging` configuration and start debugging (F5)
+
+You have done! Now it is possible to insert breakpoints and debug server and client of the tool.
\ No newline at end of file
diff --git a/README.md b/README.md
index 57234fff115c..9ed6f778b89c 100644
--- a/README.md
+++ b/README.md
@@ -82,8 +82,7 @@ Type your login/password for the superuser [on the login page](http://localhost:
 
 ### Stop all containers
 
-The command below will stop and remove containers, networks, volumes, and images
-created by `up`.
+The command below will stop and remove containers and networks created by `up`. See documentation for [docker-compose down](https://docs.docker.com/compose/reference/down/) for more details.
 
 ```bash
 docker-compose down
diff --git a/cvat/apps/engine/media.mimetypes b/cvat/apps/engine/media.mimetypes
index 289bffc4b6e1..79ee9c539e6e 100644
--- a/cvat/apps/engine/media.mimetypes
+++ b/cvat/apps/engine/media.mimetypes
@@ -196,3 +196,27 @@ image/x-kde-raw	mos
 image/x-dds	dds
 image/x-quicktime	qif
 
+# possible archive mimetypes (limited set)
+application/gzip gz
+application/rar rar
+application/x-7z-compressed 7z
+application/x-bzip bz bz2
+application/x-bzip-compressed-tar tar.bz tar.bz2 tb2 tbz tbz2
+application/x-compress z
+application/x-compressed-tar tar.gz tgz
+application/x-cpio				cpio
+application/x-gtar-compressed tgz taz
+application/x-lha lzh
+application/x-lhz lhz
+application/x-lrzip-compressed-tar tar.lrz tlrz
+application/x-lz4 lz4
+application/x-lzip lz
+application/x-lzip-compressed-tar tar.lz
+application/x-lzma lzma
+application/x-lzma-compressed-tar tar.lzma tlz
+application/x-lzop lzo
+application/x-tar gtar tar
+application/x-tarz tar.z
+application/x-tzo tar.lzo
+application/x-xz-compressed-tar txz
+application/zip zip
diff --git a/cvat/apps/engine/task.py b/cvat/apps/engine/task.py
index eb364814ad69..ce3a7b6e63de 100644
--- a/cvat/apps/engine/task.py
+++ b/cvat/apps/engine/task.py
@@ -298,6 +298,10 @@ def _parse_labels(labels):
     last_label = ""
     for token in shlex.split(labels):
         if token[0] != "~" and token[0] != "@":
+            if token in parsed_labels:
+                raise ValueError("labels string is not corect. " + 
+                    "`{}` label is specified at least twice.".format(token))
+
             parsed_labels[token] = {}
             last_label = token
         else:
@@ -306,7 +310,29 @@ def _parse_labels(labels):
             atype = match.group(2)
             aname = match.group(3)
             values = list(csv.reader(StringIO(match.group(4)), quotechar="'"))[0]
-            parsed_labels[last_label][aname] = {'prefix':prefix, 'type':atype, 'values':values}
+            attr = {'prefix':prefix, 'name':aname, 'type':atype, 'values':values, 'text':token}
+
+            if not attr['type'] in ['checkbox', 'radio', 'number', 'text', 'select']:
+                raise ValueError("labels string is not corect. " +
+                    "`{}` attribute has incorrect type {}.".format(
+                    attr['name'], attr['type']))
+
+            if attr['name'] in parsed_labels[last_label]:
+                raise ValueError("labels string is not corect. " + 
+                    "`{}` attribute is specified at least twice.".format(attr['name']))
+
+            if attr['type'] == 'checkbox': # <prefix>checkbox=name:true/false
+                if not (len(values) == 1 and values[0] in ['true', 'false']):
+                    raise ValueError("labels string is not corect. " +
+                        "`{}` attribute has incorrect value.".format(attr['name']))
+            elif attr['type'] == 'number': # <prefix>number=name:min,max,step
+                if not (len(values) == 3 and values[0].isdigit() and \
+                    values[1].isdigit() and values[2].isdigit() and \
+                    int(values[0]) < int(values[1])):
+                    raise ValueError("labels string is not corect. " +
+                        "`{}` attribute has incorrect format.".format(attr['name']))
+
+            parsed_labels[last_label][attr['name']] = attr
 
     return parsed_labels
 
@@ -437,22 +463,20 @@ def _create_thread(tid, params):
             db_job.segment = db_segment
             db_job.save()
 
-        labels = params['labels']
-        global_logger.info("labels with attributes for task #{} is {}".format(db_task.id, labels))
-        db_label = None
-        for token in shlex.split(labels):
-            if token[0] != "~" and token[0] != "@":
-                db_label = models.Label()
-                db_label.task = db_task
-                db_label.name = token
-                db_label.save()
-            elif db_label != None:
+        global_logger.info("labels with attributes for task #{} is {}".format(
+            db_task.id, params['labels']))
+        parsed_labels = _parse_labels(params['labels'])
+        for label in parsed_labels:
+            db_label = models.Label()
+            db_label.task = db_task
+            db_label.name = label
+            db_label.save()
+
+            for attr in parsed_labels[label]:
                 db_attrspec = models.AttributeSpec()
                 db_attrspec.label = db_label
-                db_attrspec.text = token
+                db_attrspec.text = parsed_labels[label][attr]['text']
                 db_attrspec.save()
-            else:
-                raise ValueError("Invalid labels format {}".format(labels))
 
     db_task.mode = mode
     db_task.save()