diff --git a/frontend/copr-frontend.spec b/frontend/copr-frontend.spec
index ed6b5a3de..0d45a65a1 100644
--- a/frontend/copr-frontend.spec
+++ b/frontend/copr-frontend.spec
@@ -94,6 +94,7 @@ BuildRequires: python3-flask-openid
 BuildRequires: python3-flask-sqlalchemy
 BuildRequires: python3-flask-whooshee
 BuildRequires: python3-flask-wtf
+BuildRequires: python3-flask-restx
 BuildRequires: python3-gobject
 BuildRequires: python3-html2text
 BuildRequires: python3-html5-parser
@@ -152,6 +153,7 @@ Requires: python3-flask-sqlalchemy
 Requires: python3-flask-whooshee
 Requires: python3-flask-wtf
 Requires: python3-flask-wtf
+Requires: python3-flask-restx
 Requires: python3-gobject
 Requires: python3-html2text
 Requires: python3-html5-parser
diff --git a/frontend/coprs_frontend/coprs/__init__.py b/frontend/coprs_frontend/coprs/__init__.py
index 67f103e18..b0052fb9f 100644
--- a/frontend/coprs_frontend/coprs/__init__.py
+++ b/frontend/coprs_frontend/coprs/__init__.py
@@ -103,6 +103,22 @@ def setup_profiler(flask_app, enabled):
 
 app.request_class = get_request_class(app)
 
+# Tell flask-restx to not append generated suggestions at
+# the end of 404 error messages
+app.config["ERROR_404_HELP"] = False
+
+# Don't display X-Fields inputs in Swagger
+app.config["RESTX_MASK_SWAGGER"] = False
+
+# There are some models, that are not used yet. They might still be helpful
+# for the users.
+app.config["RESTX_INCLUDE_ALL_MODELS"] = True
+
+# By default flask-restx expects "message" field in non-successful requests
+# but we named the field "error" instead
+app.config["ERROR_INCLUDE_MESSAGE"] = False
+
+
 from coprs.views import admin_ns
 from coprs.views.admin_ns import admin_general
 from coprs.views import api_ns
@@ -152,7 +168,7 @@ def setup_profiler(flask_app, enabled):
     NonAdminCannotDisableAutoPrunning,
 )
 from coprs.views.explore_ns import explore_ns
-from coprs.error_handlers import get_error_handler
+from coprs.error_handlers import get_error_handler, RestXErrorHandler
 import coprs.context_processors
 
 with app.app_context():
@@ -193,6 +209,16 @@ def handle_exceptions(error):
     return error_handler.handle_error(error)
 
 
+@apiv3_ns.api.errorhandler(Exception)
+def handle_exceptions_api(error):
+    """
+    Whenever an exception is raised within an API endpoint which is managed by
+    flask-restx, we end up here.
+    """
+    handler = RestXErrorHandler()
+    return handler.handle_error(error)
+
+
 app.jinja_env.trim_blocks = True
 app.jinja_env.lstrip_blocks = True
 
diff --git a/frontend/coprs_frontend/coprs/error_handlers.py b/frontend/coprs_frontend/coprs/error_handlers.py
index a7ef938ac..2d12c68aa 100644
--- a/frontend/coprs_frontend/coprs/error_handlers.py
+++ b/frontend/coprs_frontend/coprs/error_handlers.py
@@ -126,7 +126,7 @@ def render(message, code):
 
 class APIErrorHandler(BaseErrorHandler):
     """
-    Handle exceptions raised from API (v3)
+    Handle exceptions raised from API (v3) - routes without flask-restx
     """
     def override_message(self, message, error):
         return {
@@ -137,3 +137,16 @@ def override_message(self, message, error):
     @staticmethod
     def render(message, code):
         return flask.jsonify(error=message)
+
+
+class RestXErrorHandler(APIErrorHandler):
+    """
+    Handle exceptions raised from API (v3) - routes that use flask-restx
+    """
+    @staticmethod
+    def render(message, code):
+        return {"error": message}
+
+    def handle_error(self, error):
+        body, code, headers = super().handle_error(error)
+        return body, code, headers or {}
diff --git a/frontend/coprs_frontend/coprs/templates/api.html b/frontend/coprs_frontend/coprs/templates/api.html
index 09b81b8d4..baf84732a 100644
--- a/frontend/coprs_frontend/coprs/templates/api.html
+++ b/frontend/coprs_frontend/coprs/templates/api.html
@@ -59,12 +59,16 @@ <h2>API Token</h2>
     <p style="font-style:italic">You need to be logged in to see your API token.</p>
     {% endif %}
 
-    <h2>The API</h2>
+    <h2>Documentation</h2>
+
+    <ul>
+      <li><a href="/api_3/docs">API documentation</a></li>
+      <li>
+        <a href="https://python-copr.readthedocs.io/en/latest/index.html">
+          Python client documentation
+        </a>
+      </li>
+    </ul>
 
-    <p> Api documentation is available at:
-      <a href="https://python-copr.readthedocs.io/en/latest/index.html">
-        https://python-copr.readthedocs.io/en/latest/index.html
-      </a>
-    </p>
   </div>
 {% endblock %}
diff --git a/frontend/coprs_frontend/coprs/views/apiv3_ns/__init__.py b/frontend/coprs_frontend/coprs/views/apiv3_ns/__init__.py
index 2ddb54d57..d15e9f307 100644
--- a/frontend/coprs_frontend/coprs/views/apiv3_ns/__init__.py
+++ b/frontend/coprs_frontend/coprs/views/apiv3_ns/__init__.py
@@ -7,6 +7,7 @@
 from werkzeug.datastructures import ImmutableMultiDict, MultiDict
 from werkzeug.exceptions import HTTPException, NotFound, GatewayTimeout
 from sqlalchemy.orm.attributes import InstrumentedAttribute
+from flask_restx import Api, Namespace, Resource
 from coprs import app
 from coprs.exceptions import (
     AccessRestricted,
@@ -23,6 +24,30 @@
 apiv3_ns = flask.Blueprint("apiv3_ns", __name__, url_prefix="/api_3")
 
 
+# Somewhere between flask-restx 1.0.3 and 1.1.0 this change was introduced:
+# > Initializing the Api object always registers the root endpoint / even if
+# > the Swagger UI path is changed. If you wish to use the root endpoint /
+# > for other purposes, you must register it before initializing the Api object.
+# TODO That needs to get fixed and then we can move this route to apiv3_general
+# See https://github.com/python-restx/flask-restx/issues/452
+@apiv3_ns.route("/")
+def home():
+    """
+    APIv3 homepage
+    Return generic information about Copr API
+    """
+    return flask.jsonify({"version": 3})
+
+
+api = Api(
+    app=apiv3_ns,
+    version="v3",
+    title="Copr API",
+    description="See python client - <https://python-copr.readthedocs.io>",
+    doc="/docs",
+)
+
+
 # HTTP methods
 GET = ["GET"]
 POST = ["POST"]
diff --git a/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_builds.py b/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_builds.py
index deb53e9f3..a192212a3 100644
--- a/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_builds.py
+++ b/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_builds.py
@@ -1,15 +1,24 @@
+# All documentation is to be written on method-level because then it is
+# recognized by flask-restx and rendered in Swagger
+# pylint: disable=missing-class-docstring
+
 import os
 import flask
 from sqlalchemy.orm import joinedload
 
 from werkzeug.datastructures import MultiDict
 from werkzeug.utils import secure_filename
+from flask_restx import Namespace, Resource
 
 from copr_common.enums import StatusEnum
 from coprs import db, forms, models
 from coprs.exceptions import (BadRequest, AccessRestricted)
 from coprs.views.misc import api_login_required
-from coprs.views.apiv3_ns import apiv3_ns, rename_fields_helper
+from coprs.views.apiv3_ns import apiv3_ns, api, rename_fields_helper
+from coprs.views.apiv3_ns.schema import (
+    build_model,
+    get_build_params,
+)
 from coprs.logic.complex_logic import ComplexLogic
 from coprs.logic.builds_logic import BuildsLogic
 
@@ -28,6 +37,12 @@
 from .json2form import get_form_compatible_data
 
 
+
+
+apiv3_builds_ns = Namespace("build", description="Builds")
+api.add_namespace(apiv3_builds_ns)
+
+
 def to_dict(build):
     return {
         "id": build.id,
@@ -76,11 +91,24 @@ def render_build(build):
     return flask.jsonify(to_dict(build))
 
 
-@apiv3_ns.route("/build/<int:build_id>/", methods=GET)
-@apiv3_ns.route("/build/<int:build_id>", methods=GET)
-def get_build(build_id):
-    build = ComplexLogic.get_build_safe(build_id)
-    return render_build(build)
+@apiv3_builds_ns.route("/<int:build_id>")
+class GetBuild(Resource):
+
+    @apiv3_builds_ns.doc(params=get_build_params)
+    @apiv3_builds_ns.marshal_with(build_model)
+    def get(self, build_id):
+        """
+        Get a build
+        Get details for a single Copr build.
+        """
+        build = ComplexLogic.get_build_safe(build_id)
+        result = to_dict(build)
+
+        # Workaround - `marshal_with` needs the input `build_id` to be present
+        # in the returned dict. Don't worry, it won't get to the end user, it
+        # will be stripped away.
+        result["build_id"] = result["id"]
+        return result
 
 
 @apiv3_ns.route("/build/list/", methods=GET)
diff --git a/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_general.py b/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_general.py
index fa57fa44a..9c301ad22 100644
--- a/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_general.py
+++ b/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_general.py
@@ -1,11 +1,16 @@
+# All documentation is to be written on method-level because then it is
+# recognized by flask-restx and rendered in Swagger
+# pylint: disable=missing-class-docstring
+
 import os
 import re
 from fnmatch import fnmatch
 
 import flask
+from flask_restx import Namespace
 
 from coprs import app, oid, db
-from coprs.views.apiv3_ns import apiv3_ns
+from coprs.views.apiv3_ns import apiv3_ns, api
 from coprs.exceptions import AccessRestricted
 from coprs.views.misc import api_login_required
 from coprs.auth import UserAuth
@@ -53,9 +58,9 @@ def krb_straighten_username(krb_remote_user):
     return username
 
 
-@apiv3_ns.route("/")
-def home():
-    return flask.jsonify({"version": 3})
+apiv3_general_ns = Namespace("home", path="/",
+                             description="APIv3 general endpoints")
+api.add_namespace(apiv3_general_ns)
 
 
 @apiv3_ns.route("/auth-check")
diff --git a/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_packages.py b/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_packages.py
index 1c93b135f..fbda9221b 100644
--- a/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_packages.py
+++ b/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_packages.py
@@ -1,4 +1,9 @@
+# All documentation is to be written on method-level because then it is
+# recognized by flask-restx and rendered in Swagger
+# pylint: disable=missing-class-docstring
+
 import flask
+from flask_restx import Namespace, Resource
 
 from coprs.exceptions import (
         BadRequest,
@@ -12,7 +17,15 @@
 )
 from coprs.views.misc import api_login_required
 from coprs import db, models, forms, helpers
-from coprs.views.apiv3_ns import apiv3_ns, rename_fields_helper
+from coprs.views.apiv3_ns import apiv3_ns, api, rename_fields_helper
+from coprs.views.apiv3_ns.schema import (
+    package_model,
+    add_package_params,
+    edit_package_params,
+    get_package_parser,
+    add_package_parser,
+    edit_package_parser,
+)
 from coprs.logic.packages_logic import PackagesLogic
 
 # @TODO if we need to do this on several places, we should figure a better way to do it
@@ -25,6 +38,10 @@
 MAX_PACKAGES_WITHOUT_PAGINATION = 10000
 
 
+apiv3_packages_ns = Namespace("package", description="Packages")
+api.add_namespace(apiv3_packages_ns)
+
+
 def to_dict(package, with_latest_build=False, with_latest_succeeded_build=False):
     source_dict = package.source_json_dict
     if "srpm_build_method" in source_dict:
@@ -91,19 +108,29 @@ def get_arg_to_bool(argument):
     return False
 
 
-@apiv3_ns.route("/package", methods=GET)
-@query_params()
-def get_package(ownername, projectname, packagename,
-                with_latest_build=False, with_latest_succeeded_build=False):
-    with_latest_build = get_arg_to_bool(with_latest_build)
-    with_latest_succeeded_build = get_arg_to_bool(with_latest_succeeded_build)
+@apiv3_packages_ns.route("/")
+class GetPackage(Resource):
+    parser = get_package_parser()
 
-    copr = get_copr(ownername, projectname)
-    try:
-        package = PackagesLogic.get(copr.id, packagename)[0]
-    except IndexError:
-        raise ObjectNotFound("No package with name {name} in copr {copr}".format(name=packagename, copr=copr.name))
-    return flask.jsonify(to_dict(package, with_latest_build, with_latest_succeeded_build))
+    @apiv3_packages_ns.expect(parser)
+    @apiv3_packages_ns.marshal_with(package_model)
+    def get(self):
+        """
+        Get a package
+        Get a single package from a Copr project.
+        """
+        args = self.parser.parse_args()
+        with_latest_build = args.with_latest_build
+        with_latest_succeeded_build = args.with_latest_succeeded_build
+
+        copr = get_copr(args.ownername, args.projectname)
+        try:
+            package = PackagesLogic.get(copr.id, args.packagename)[0]
+        except IndexError as ex:
+            msg = ("No package with name {name} in copr {copr}"
+                   .format(name=args.packagename, copr=copr.name))
+            raise ObjectNotFound(msg) from ex
+        return to_dict(package, with_latest_build, with_latest_succeeded_build)
 
 
 @apiv3_ns.route("/package/list", methods=GET)
@@ -111,6 +138,10 @@ def get_package(ownername, projectname, packagename,
 @query_params()
 def get_package_list(ownername, projectname, with_latest_build=False,
                      with_latest_succeeded_build=False, **kwargs):
+    """
+    Get a list of packages
+    Get a list of packages from a Copr project
+    """
 
     with_latest_build = get_arg_to_bool(with_latest_build)
     with_latest_succeeded_build = get_arg_to_bool(with_latest_succeeded_build)
@@ -138,30 +169,58 @@ def get_package_list(ownername, projectname, with_latest_build=False,
     return flask.jsonify(items=items, meta=paginator.meta)
 
 
-@apiv3_ns.route("/package/add/<ownername>/<projectname>/<package_name>/<source_type_text>", methods=POST)
-@api_login_required
-def package_add(ownername, projectname, package_name, source_type_text):
-    copr = get_copr(ownername, projectname)
-    data = rename_fields(get_form_compatible_data(preserve=["python_versions"]))
-    process_package_add_or_edit(copr, source_type_text, data=data)
-    package = PackagesLogic.get(copr.id, package_name).first()
-    return flask.jsonify(to_dict(package))
-
-
-@apiv3_ns.route("/package/edit/<ownername>/<projectname>/<package_name>/<source_type_text>", methods=PUT)
-@api_login_required
-def package_edit(ownername, projectname, package_name, source_type_text=None):
-    copr = get_copr(ownername, projectname)
-    data = rename_fields(get_form_compatible_data(preserve=["python_versions"]))
-    try:
-        package = PackagesLogic.get(copr.id, package_name)[0]
-        source_type_text = source_type_text or package.source_type_text
-    except IndexError:
-        raise ObjectNotFound("Package {name} does not exists in copr {copr}."
-                             .format(name=package_name, copr=copr.full_name))
-
-    process_package_add_or_edit(copr, source_type_text, package=package, data=data)
-    return flask.jsonify(to_dict(package))
+@apiv3_packages_ns.route("/add/<ownername>/<projectname>/<package_name>/<source_type_text>")
+class PackageAdd(Resource):
+    parser = add_package_parser()
+
+    @api_login_required
+    @apiv3_packages_ns.doc(params=add_package_params)
+    @apiv3_packages_ns.expect(parser)
+    @apiv3_packages_ns.marshal_with(package_model)
+    def post(self, ownername, projectname, package_name, source_type_text):
+        """
+        Create a package
+        Create a new package inside a specified Copr project.
+
+        See what fields are required for which source types:
+        https://python-copr.readthedocs.io/en/latest/client_v3/package_source_types.html
+        """
+        copr = get_copr(ownername, projectname)
+        data = rename_fields(get_form_compatible_data(preserve=["python_versions"]))
+        process_package_add_or_edit(copr, source_type_text, data=data)
+        package = PackagesLogic.get(copr.id, package_name).first()
+        return to_dict(package)
+
+
+@apiv3_packages_ns.route("/edit/<ownername>/<projectname>/<package_name>/")
+@apiv3_packages_ns.route("/edit/<ownername>/<projectname>/<package_name>/<source_type_text>")
+class PackageEdit(Resource):
+    parser = edit_package_parser()
+
+    @api_login_required
+    @apiv3_packages_ns.doc(params=edit_package_params)
+    @apiv3_packages_ns.expect(parser)
+    @apiv3_packages_ns.marshal_with(package_model)
+    def post(self, ownername, projectname, package_name, source_type_text=None):
+        """
+        Edit a package
+        Edit an existing package within a Copr project.
+
+        See what fields are required for which source types:
+        https://python-copr.readthedocs.io/en/latest/client_v3/package_source_types.html
+        """
+        copr = get_copr(ownername, projectname)
+        data = rename_fields(get_form_compatible_data(preserve=["python_versions"]))
+        try:
+            package = PackagesLogic.get(copr.id, package_name)[0]
+            source_type_text = source_type_text or package.source_type_text
+        except IndexError as ex:
+            msg = ("Package {name} does not exists in copr {copr}."
+                   .format(name=package_name, copr=copr.full_name))
+            raise ObjectNotFound(msg) from ex
+
+        process_package_add_or_edit(copr, source_type_text, package=package, data=data)
+        return to_dict(package)
 
 
 @apiv3_ns.route("/package/reset", methods=PUT)
diff --git a/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_project_chroots.py b/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_project_chroots.py
index d6a6f1c68..0fe3f9ab1 100644
--- a/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_project_chroots.py
+++ b/frontend/coprs_frontend/coprs/views/apiv3_ns/apiv3_project_chroots.py
@@ -1,15 +1,23 @@
+# All documentation is to be written on method-level because then it is
+# recognized by flask-restx and rendered in Swagger
+# pylint: disable=missing-class-docstring
+
 import flask
+from flask_restx import Namespace, Resource
 from coprs.views.misc import api_login_required
-from coprs.views.apiv3_ns import apiv3_ns, rename_fields_helper
+from coprs.views.apiv3_ns import apiv3_ns, api, rename_fields_helper
+from coprs.views.apiv3_ns.schema import (
+    project_chroot_model,
+    project_chroot_build_config_model,
+    project_chroot_parser,
+)
 from coprs.logic.complex_logic import ComplexLogic, BuildConfigLogic
 from coprs.exceptions import ObjectNotFound, InvalidForm
 from coprs import db, forms
 from coprs.logic.coprs_logic import CoprChrootsLogic
 from . import (
-    query_params,
     get_copr,
     file_upload,
-    GET,
     PUT,
     str_to_list,
     reset_to_defaults,
@@ -17,6 +25,11 @@
 from .json2form import get_form_compatible_data
 
 
+apiv3_project_chroots_ns = \
+    Namespace("project-chroot", description="Project chroots")
+api.add_namespace(apiv3_project_chroots_ns)
+
+
 def to_dict(project_chroot):
     return {
         "mock_chroot": project_chroot.mock_chroot.name,
@@ -40,7 +53,7 @@ def to_build_config_dict(project_chroot):
         "repos": config["repos"],
         "additional_repos": BuildConfigLogic.generate_additional_repos(project_chroot),
         "additional_packages": (project_chroot.buildroot_pkgs or "").split(),
-        "additional_modules": project_chroot.module_toggle,
+        "additional_modules": str_to_list(project_chroot.module_toggle),
         "enable_net": project_chroot.copr.enable_net,
         "with_opts":  str_to_list(project_chroot.with_opts),
         "without_opts": str_to_list(project_chroot.without_opts),
@@ -59,23 +72,41 @@ def rename_fields(input_dict):
         "additional_modules": "module_toggle",
     })
 
-@apiv3_ns.route("/project-chroot", methods=GET)
-@query_params()
-def get_project_chroot(ownername, projectname, chrootname):
-    copr = get_copr(ownername, projectname)
-    chroot = ComplexLogic.get_copr_chroot_safe(copr, chrootname)
-    return flask.jsonify(to_dict(chroot))
 
+@apiv3_project_chroots_ns.route("/")
+class ProjectChroot(Resource):
+    parser = project_chroot_parser()
 
-@apiv3_ns.route("/project-chroot/build-config", methods=GET)
-@query_params()
-def get_build_config(ownername, projectname, chrootname):
-    copr = get_copr(ownername, projectname)
-    chroot = ComplexLogic.get_copr_chroot_safe(copr, chrootname)
-    if not chroot:
-        raise ObjectNotFound('Chroot not found.')
-    config = to_build_config_dict(chroot)
-    return flask.jsonify(config)
+    @apiv3_project_chroots_ns.expect(parser)
+    @apiv3_project_chroots_ns.marshal_with(project_chroot_model)
+    def get(self):
+        """
+        Get a project chroot
+        Get settings for a single project chroot.
+        """
+        args = self.parser.parse_args()
+        copr = get_copr(args.ownername, args.projectname)
+        chroot = ComplexLogic.get_copr_chroot_safe(copr, args.chrootname)
+        return to_dict(chroot)
+
+
+@apiv3_project_chroots_ns.route("/build-config")
+class BuildConfig(Resource):
+    parser = project_chroot_parser()
+
+    @apiv3_project_chroots_ns.expect(parser)
+    @apiv3_project_chroots_ns.marshal_with(project_chroot_build_config_model)
+    def get(self):
+        """
+        Get a build config
+        Generate a build config based on a project chroot settings.
+        """
+        args = self.parser.parse_args()
+        copr = get_copr(args.ownername, args.projectname)
+        chroot = ComplexLogic.get_copr_chroot_safe(copr, args.chrootname)
+        if not chroot:
+            raise ObjectNotFound('Chroot not found.')
+        return to_build_config_dict(chroot)
 
 
 @apiv3_ns.route("/project-chroot/edit/<ownername>/<projectname>/<chrootname>", methods=PUT)
diff --git a/frontend/coprs_frontend/coprs/views/apiv3_ns/schema.py b/frontend/coprs_frontend/coprs/views/apiv3_ns/schema.py
new file mode 100644
index 000000000..58375a5b7
--- /dev/null
+++ b/frontend/coprs_frontend/coprs/views/apiv3_ns/schema.py
@@ -0,0 +1,548 @@
+"""
+Sometime in the future, we can maybe drop this whole file and generate schemas
+from SQLAlchemy models:
+https://github.com/python-restx/flask-restx/pull/493/files
+
+Things used for the output:
+
+- *_schema - describes our output schemas
+- *_field  - a schema is a dict of named fields
+- *_model  - basically a pair schema and its name
+
+
+Things used for parsing the input:
+
+- *_parser - for documenting query parameters in URL and
+             parsing POST values in input JSON
+- *_arg    - a parser is composed from arguments
+- *_params - for documenting path parameters in URL because parser
+             can't be properly used for them [1]
+
+[1] https://github.com/noirbizarre/flask-restplus/issues/146#issuecomment-212968591
+"""
+
+
+from flask_restx.reqparse import Argument, RequestParser
+from flask_restx.fields import String, List, Integer, Boolean, Nested, Url, Raw
+from flask_restx.inputs import boolean
+from coprs.views.apiv3_ns import api
+
+
+id_field = Integer(
+    description="Numeric ID",
+    example=123,
+)
+
+mock_chroot_field = String(
+    description="Mock chroot",
+    example="fedora-rawhide-x86_64",
+)
+
+ownername_field = String(
+    description="User or group name",
+    example="@copr",
+)
+
+projectname_field = String(
+    description="Name of the project",
+    example="copr-dev",
+)
+
+project_dirname_field = String(
+    description="",
+    example="copr-dev:pr:123",
+)
+
+packagename_field = String(
+    description="Name of the package",
+    example="copr-cli",
+)
+
+comps_name_field = String(
+    description="Name of the comps.xml file",
+)
+
+additional_repos_field = List(
+    String,
+    description="Additional repos to be used for builds in this chroot",
+)
+
+additional_packages_field = List(
+    String,
+    description="Additional packages to be always present in minimal buildroot",
+)
+
+additional_modules_field = List(
+    String,
+    description=("List of modules that will be enabled "
+                 "or disabled in the given chroot"),
+    example=["module1:stream", "!module2:stream"],
+)
+
+with_opts_field = List(
+    String,
+    description="Mock --with option",
+)
+
+without_opts_field = List(
+    String,
+    description="Mock --without option",
+)
+
+delete_after_days_field = Integer(
+    description="The project will be automatically deleted after this many days",
+    example=30,
+)
+
+isolation_field = String(
+    description=("Mock isolation feature setup. Possible values "
+                 "are 'default', 'simple', 'nspawn'."),
+    example="nspawn",
+)
+
+enable_net_field = Boolean(
+    description="Enable internet access during builds",
+)
+
+source_type_field = String(
+    description=("See https://python-copr.readthedocs.io"
+                 "/en/latest/client_v3/package_source_types.html"),
+    example="scm",
+)
+
+scm_type_field = String(
+    default="Possible values are 'git', 'svn'",
+    example="git",
+)
+
+source_build_method_field = String(
+    description="https://docs.pagure.org/copr.copr/user_documentation.html#scm",
+    example="tito",
+)
+
+pypi_package_name_field = String(
+    description="Package name in the Python Package Index.",
+    example="copr",
+)
+
+pypi_package_version_field = String(
+    description="PyPI package version",
+    example="1.128pre",
+)
+
+# TODO We are copy-pasting descriptions from web UI to this file. This field
+# is an ideal candidate for figuring out how to share the descriptions
+pypi_spec_generator_field = String(
+    description=("Tool for generating specfile from a PyPI package. "
+                 "The options are full-featured pyp2rpm with cross "
+                 "distribution support, and pyp2spec that is being actively "
+                 "developed and considered to be the future."),
+    example="pyp2spec",
+)
+
+pypi_spec_template_field = String(
+    description=("Name of the spec template. "
+                 "This option is limited to pyp2rpm spec generator."),
+    example="default",
+)
+
+pypi_versions_field = List(
+    String,  # We currently return string but should this be number?
+    description=("For what python versions to build. "
+                 "This option is limited to pyp2rpm spec generator."),
+    example=["3", "2"],
+)
+
+auto_rebuild_field = Boolean(
+    description="Auto-rebuild the package? (i.e. every commit or new tag)",
+)
+
+clone_url_field = String(
+    description="URL to your Git or SVN repository",
+    example="https://github.com/fedora-copr/copr.git",
+)
+
+committish_field = String(
+    description="Specific branch, tag, or commit that you want to build",
+    example="main",
+)
+
+subdirectory_field = String(
+    description="Subdirectory where source files and .spec are located",
+    example="cli",
+)
+
+spec_field = String(
+    description="Path to your .spec file under the specified subdirectory",
+    example="copr-cli.spec",
+)
+
+chroots_field = List(
+    String,
+    description="List of chroot names",
+    example=["fedora-37-x86_64", "fedora-rawhide-x86_64"],
+)
+
+submitted_on_field = Integer(
+    description="Timestamp when the build was submitted",
+    example=1677695304,
+)
+
+started_on_field = Integer(
+    description="Timestamp when the build started",
+    example=1677695545,
+)
+
+ended_on_field = Integer(
+    description="Timestamp when the build ended",
+    example=1677695963,
+)
+
+is_background_field = Boolean(
+    description="The build is marked as a background job",
+)
+
+submitter_field = String(
+    description="Username of the person who submitted this build",
+    example="frostyx",
+)
+
+state_field = String(
+    description="",
+    example="succeeded",
+)
+
+repo_url_field = Url(
+    description="See REPO OPTIONS in `man 5 dnf.conf`",
+    example="https://download.copr.fedorainfracloud.org/results/@copr/copr-dev/fedora-$releasever-$basearch/",
+)
+
+max_builds_field = Integer(
+    description=("Keep only the specified number of the newest-by-id builds "
+                 "(garbage collector is run daily)"),
+    example=10,
+)
+
+source_package_url_field = String(
+    description="URL for downloading the SRPM package"
+)
+
+source_package_version_field = String(
+    description="Package version",
+    example="1.105-1.git.53.319c6de",
+)
+
+gem_name_field = String(
+    description="Gem name from RubyGems.org",
+    example="hello",
+)
+
+custom_script_field = String(
+    description="Script code to produce a SRPM package",
+    example="#! /bin/sh -x",
+)
+
+custom_builddeps_field = String(
+    description="URL to additional yum repos, which can be used during build.",
+    example="copr://@copr/copr",
+)
+
+custom_resultdir_field = String(
+    description="Directory where SCRIPT generates sources",
+    example="./_build",
+)
+
+custom_chroot_field = String(
+    description="What chroot to run the script in",
+    example="fedora-latest-x86_64",
+)
+
+limit_field = Integer(
+    description="Limit",
+    example=20,
+)
+
+offset_field = Integer(
+    description="Offset",
+    example=0,
+)
+
+order_field = String(
+    description="Order by",
+    example="id",
+)
+
+order_type_field = String(
+    description="Order type",
+    example="DESC",
+)
+
+pagination_schema = {
+    "limit_field": limit_field,
+    "offset_field": offset_field,
+    "order_field": order_field,
+    "order_type_field": order_type_field,
+}
+
+pagination_model = api.model("Pagination", pagination_schema)
+
+project_chroot_schema = {
+    "mock_chroot": mock_chroot_field,
+    "ownername": ownername_field,
+    "projectname": projectname_field,
+    "comps_name": comps_name_field,
+    "additional_repos": additional_repos_field,
+    "additional_packages": additional_packages_field,
+    "additional_modules": additional_modules_field,
+    "with_opts": with_opts_field,
+    "without_opts": without_opts_field,
+    "delete_after_days": delete_after_days_field,
+    "isolation": isolation_field,
+}
+
+project_chroot_model = api.model("ProjectChroot", project_chroot_schema)
+
+repo_schema = {
+    "baseurl": String,
+    "id": String(example="copr_base"),
+    "name": String(example="Copr repository"),
+}
+
+repo_model = api.model("Repo", repo_schema)
+
+project_chroot_build_config_schema = {
+    "chroot": mock_chroot_field,
+    "repos": List(Nested(repo_model)),
+    "additional_repos": additional_repos_field,
+    "additional_packages": additional_packages_field,
+    "additional_modules": additional_modules_field,
+    "enable_net": enable_net_field,
+    "with_opts":  with_opts_field,
+    "without_opts": without_opts_field,
+    "isolation": isolation_field,
+}
+
+project_chroot_build_config_model = \
+    api.model("ProjectChrootBuildConfig", project_chroot_build_config_schema)
+
+source_dict_scm_schema = {
+    "clone_url": clone_url_field,
+    "committish": committish_field,
+    "source_build_method": source_build_method_field,
+    "spec": spec_field,
+    "subdirectory": subdirectory_field,
+    "type": scm_type_field,
+}
+
+source_dict_scm_model = api.model("SourceDictSCM", source_dict_scm_schema)
+
+source_dict_pypi_schema = {
+    "pypi_package_name": pypi_package_name_field,
+    "pypi_package_version": pypi_package_version_field,
+    "spec_generator": pypi_spec_generator_field,
+    "spec_template": pypi_spec_template_field,
+    "python_versions": pypi_versions_field,
+}
+
+source_dict_pypi_model = api.model("SourceDictPyPI", source_dict_pypi_schema)
+
+source_package_schema = {
+    "name": packagename_field,
+    "url": source_package_url_field,
+    "version": source_package_version_field,
+}
+
+source_package_model = api.model("SourcePackage", source_package_schema)
+
+build_schema = {
+    "chroots": chroots_field,
+    "ended_on": ended_on_field,
+    "id": id_field,
+    "is_background": is_background_field,
+    "ownername": ownername_field,
+    "project_dirname": project_dirname_field,
+    "projectname": projectname_field,
+    "repo_url": repo_url_field,
+    "source_package": Nested(source_package_model),
+    "started_on": started_on_field,
+    "state": state_field,
+    "submitted_on": submitted_on_field,
+    "submitter": submitter_field,
+}
+
+build_model = api.model("Build", build_schema)
+
+package_builds_schema = {
+    "latest": Nested(build_model, allow_null=True),
+    "latest_succeeded": Nested(build_model, allow_null=True),
+}
+
+package_builds_model = api.model("PackageBuilds", package_builds_schema)
+
+# TODO We use this schema for both GetPackage and PackageEdit. The `builds`
+# field is returned for both but only in case of GetPackage it can contain
+# results. How should we document this?
+package_schema = {
+    "id": id_field,
+    "name": packagename_field,
+    "projectname": projectname_field,
+    "ownername": ownername_field,
+    "source_type": source_type_field,
+    # TODO Somehow a Polymorh should be used here for `source_dict_scm_model`,
+    # `source_dict_pypi_model`, etc. I don't know how, so leaving an
+    # undocumented value for the time being.
+    "source_dict": Raw,
+    "auto_rebuild": auto_rebuild_field,
+    "builds": Nested(package_builds_model),
+}
+
+package_model = api.model("Package", package_schema)
+
+
+def clone(field):
+    """
+    Return a copy of a field
+    """
+    kwargs = field.__dict__.copy()
+    return field.__class__(**kwargs)
+
+
+add_package_params = {
+    "ownername": ownername_field.description,
+    "projectname": projectname_field.description,
+    "package_name": packagename_field.description,
+    "source_type_text": source_type_field.description,
+}
+
+edit_package_params = {
+    **add_package_params,
+    "source_type_text": source_type_field.description,
+}
+
+get_build_params = {
+    "build_id": id_field.description,
+}
+
+def to_arg_type(field):
+    """
+    Take a field on the input, find out its type and convert it to a type that
+    can be used with `RequestParser`.
+    """
+    types = {
+        Integer: int,
+        String: str,
+        Boolean: boolean,
+        List: list,
+    }
+    for key, value in types.items():
+        if isinstance(field, key):
+            return value
+    raise RuntimeError("Unknown field type: {0}"
+                       .format(field.__class__.__name__))
+
+
+def field2arg(name, field, **kwargs):
+    """
+    Take a field on the input and create an `Argument` for `RequestParser`
+    based on it.
+    """
+    return Argument(
+        name,
+        type=to_arg_type(field),
+        help=field.description,
+        **kwargs,
+    )
+
+
+def merge_parsers(a, b):
+    """
+    Take two `RequestParser` instances and create a new one, combining all of
+    their arguments.
+    """
+    parser = RequestParser()
+    for arg in a.args + b.args:
+        parser.add_argument(arg)
+    return parser
+
+
+def get_package_parser():
+    # pylint: disable=missing-function-docstring
+    parser = RequestParser()
+    parser.add_argument(field2arg("ownername", ownername_field, required=True))
+    parser.add_argument(field2arg("projectname", projectname_field, required=True))
+    parser.add_argument(field2arg("packagename", packagename_field, required=True))
+
+    parser.add_argument(
+        "with_latest_build", type=boolean, required=False, default=False,
+        help=(
+            "The result will contain 'builds' dictionary with the latest "
+            "submitted build of this particular package within the project"))
+
+    parser.add_argument(
+        "with_latest_succeeded_build", type=boolean, required=False, default=False,
+        help=(
+            "The result will contain 'builds' dictionary with the latest "
+            "successful build of this particular package within the project."))
+
+    return parser
+
+
+def add_package_parser():
+    # pylint: disable=missing-function-docstring
+    args = [
+        # SCM
+        field2arg("clone_url", clone_url_field),
+        field2arg("committish", committish_field),
+        field2arg("subdirectory", subdirectory_field),
+        field2arg("spec", spec_field),
+        field2arg("scm_type", scm_type_field),
+
+        # Rubygems
+        field2arg("gem_name", gem_name_field),
+
+        # PyPI
+        field2arg("pypi_package_name", pypi_package_name_field),
+        field2arg("pypi_package_version", pypi_package_version_field),
+        field2arg("spec_generator", pypi_spec_generator_field),
+        field2arg("spec_template", pypi_spec_template_field),
+        field2arg("python_versions", pypi_versions_field),
+
+        # Custom
+        field2arg("script", custom_script_field),
+        field2arg("builddeps", custom_builddeps_field),
+        field2arg("resultdir", custom_resultdir_field),
+        field2arg("chroot", custom_chroot_field),
+
+
+        field2arg("packagename", packagename_field),
+        field2arg("source_build_method", source_build_method_field),
+        field2arg("max_builds", max_builds_field),
+        field2arg("webhook_rebuild", auto_rebuild_field),
+    ]
+    parser = RequestParser()
+    for arg in args:
+        arg.location = "json"
+        parser.add_argument(arg)
+    return parser
+
+
+def edit_package_parser():
+    # pylint: disable=missing-function-docstring
+    parser = add_package_parser().copy()
+    for arg in parser.args:
+        arg.required = False
+    return parser
+
+
+def project_chroot_parser():
+    # pylint: disable=missing-function-docstring
+    parser = RequestParser()
+    args = [
+        field2arg("ownername", ownername_field),
+        field2arg("projectname", projectname_field),
+        field2arg("chrootname", mock_chroot_field),
+    ]
+    for arg in args:
+        arg.required = True
+        parser.add_argument(arg)
+    return parser