diff --git a/.coveragerc b/.coveragerc
index 90b06f40..d2ef0864 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -10,6 +10,7 @@ omit=
 	oar/tools/__init__.py
 	oar/cli/oar2trace.py
 	oar/cli/_oarbench.py
+	oar/cli/oarproxycleaner.py
 
 [report]
 exclude_lines =
diff --git a/flake.lock b/flake.lock
index 44b23d49..8ab2ebf4 100644
--- a/flake.lock
+++ b/flake.lock
@@ -5,11 +5,11 @@
         "systems": "systems"
       },
       "locked": {
-        "lastModified": 1681202837,
-        "narHash": "sha256-H+Rh19JDwRtpVPAWp64F+rlEtxUWBAQW28eAi3SRSzg=",
+        "lastModified": 1694529238,
+        "narHash": "sha256-zsNZZGTGnMOf9YpHKJqMSsa0dXbfmxeoJ7xHlrt+xmY=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "cfacdce06f30d2b68473a46042957675eebb3401",
+        "rev": "ff7b65b44d01cf9ba6a71320833626af21126384",
         "type": "github"
       },
       "original": {
@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1687017257,
-        "narHash": "sha256-jbk0Szj1DPe9KwySeMr3KzYqW1JaUKJ6lYwSLMvc1n0=",
+        "lastModified": 1701053011,
+        "narHash": "sha256-8QQ7rFbKFqgKgLoaXVJRh7Ik5LtI3pyBBCfOnNOGkF0=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "aaef163eac75c2ac7f882c1fae4e0c08aa18d186",
+        "rev": "5b528f99f73c4fad127118a8c1126b5e003b01a9",
         "type": "github"
       },
       "original": {
diff --git a/oar/cli/oarconnect.py b/oar/cli/oarconnect.py
index e983f1a4..ab13ee14 100644
--- a/oar/cli/oarconnect.py
+++ b/oar/cli/oarconnect.py
@@ -9,13 +9,19 @@
 
 @click.command()
 @click.argument("job_id", nargs=1, required=True, type=int)
-def cli(job_id):
+@click.pass_context
+def cli(ctx, job_id):
     """Connect to a reservation in Running state."""
 
-    config, engine, log = init_oar()
-    session_factory = sessionmaker(bind=engine)
-    scoped = scoped_session(session_factory)
-    session = scoped()
+    ctx = click.get_current_context()
+    if ctx.obj:
+        (session, config) = ctx.obj
+    else:
+        config, engine, log = init_oar()
+
+        session_factory = sessionmaker(bind=engine)
+        scoped = scoped_session(session_factory)
+        session = scoped()
 
     cmd_ret = CommandReturns()
     openssh_cmd = config["OPENSSH_CMD"]
diff --git a/oar/cli/oarsub.py b/oar/cli/oarsub.py
index 1e2a8c8b..c56cfa7f 100644
--- a/oar/cli/oarsub.py
+++ b/oar/cli/oarsub.py
@@ -247,13 +247,7 @@ def connect_job(session, config, job_id, stop_oarexec, openssh_cmd, cmd_ret):
             )
 
         if (luser != job.user) and (luser != "oar"):
-            cmd_ret.error(
-                "User mismatch for job "
-                + str(job_id)
-                + " (job user is "
-                + job.user
-                + "."
-            )
+            cmd_ret.error(f"User mismatch for job {job_id} (job user is {job.user})")
         cmd_ret.exit(20)
 
     cmd_ret.exit(0)
diff --git a/oar/lib/models.py b/oar/lib/models.py
index 9170e2ce..8352dc13 100644
--- a/oar/lib/models.py
+++ b/oar/lib/models.py
@@ -20,7 +20,7 @@
 
 from oar.lib.database import Database
 
-from .utils import reraise, to_json
+from .utils import reraise
 
 # from .globals import db
 
@@ -75,12 +75,6 @@ def to_dict(self, ignore_keys=()):
 
     asdict = to_dict
 
-    def to_json(self, **kwargs):
-        """Dump `self` to json string."""
-        kwargs.setdefault("ignore_keys", ())
-        obj = self.to_dict(kwargs.pop("ignore_keys"))
-        return to_json(obj, **kwargs)
-
     def __iter__(self):
         """Return an iterable that supports .next()"""
         for key, value in (self.asdict()).items():
diff --git a/oar/lib/utils.py b/oar/lib/utils.py
index 6dd71afd..221a4d0a 100644
--- a/oar/lib/utils.py
+++ b/oar/lib/utils.py
@@ -1,8 +1,6 @@
 # -*- coding: utf-8 -*-
 
 import copy
-import datetime
-import decimal
 import os
 import re
 import sys
@@ -10,8 +8,6 @@
 from collections.abc import Callable
 from decimal import Decimal, InvalidOperation
 
-import simplejson as json
-
 basestring = (str, bytes)
 integer_types = (int,)
 numeric_types = integer_types + (float,)
@@ -78,35 +74,6 @@ def callable(obj):
     return isinstance(obj, Callable)
 
 
-class JSONEncoder(json.JSONEncoder):
-    """JSON Encoder class that handles conversion for a number of types not
-    supported by the default json library, especially the sqlalchemy objects.
-
-    :returns: object that can be converted to json
-    """
-
-    def default(self, obj):
-        if isinstance(obj, (datetime.datetime, datetime.date, datetime.time)):
-            return obj.isoformat()
-        elif isinstance(obj, (decimal.Decimal)):
-            return to_unicode(obj)
-        elif hasattr(obj, "asdict") and callable(getattr(obj, "asdict")):
-            return obj.asdict()
-        elif hasattr(obj, "to_dict") and callable(getattr(obj, "to_dict")):
-            return obj.to_dict()
-        else:
-            return json.JSONEncoder.default(self, obj)
-
-
-def to_json(obj, **kwargs):
-    """Dumps object to json string."""
-    kwargs.setdefault("ensure_ascii", False)
-    kwargs.setdefault("cls", JSONEncoder)
-    kwargs.setdefault("indent", 4)
-    kwargs.setdefault("separators", (",", ": "))
-    return json.dumps(obj, **kwargs)
-
-
 def touch(fname, times=None):
     dirname = "/".join(fname.split("/")[:-1])
     if not os.path.exists(dirname):
diff --git a/poetry.lock b/poetry.lock
index 159fd2fa..e754f035 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -2583,6 +2583,21 @@ platformdirs = ">=3.9.1,<4"
 docs = ["furo (>=2023.7.26)", "proselint (>=0.13)", "sphinx (>=7.1.2)", "sphinx-argparse (>=0.4)", "sphinxcontrib-towncrier (>=0.2.1a0)", "towncrier (>=23.6)"]
 test = ["covdefaults (>=2.3)", "coverage (>=7.2.7)", "coverage-enable-subprocess (>=1)", "flaky (>=3.7)", "packaging (>=23.1)", "pytest (>=7.4)", "pytest-env (>=0.8.2)", "pytest-freezer (>=0.4.8)", "pytest-mock (>=3.11.1)", "pytest-randomly (>=3.12)", "pytest-timeout (>=2.1)", "setuptools (>=68)", "time-machine (>=2.10)"]
 
+[[package]]
+name = "vulture"
+version = "2.10"
+description = "Find dead code"
+category = "dev"
+optional = false
+python-versions = ">=3.8"
+files = [
+    {file = "vulture-2.10-py2.py3-none-any.whl", hash = "sha256:568a4176db7468d0157817ae3bb1847a19f1ddc629849af487f9d3b279bff77d"},
+    {file = "vulture-2.10.tar.gz", hash = "sha256:2a5c3160bffba77595b6e6dfcc412016bd2a09cd4b66cdf7fbba913684899f6f"},
+]
+
+[package.dependencies]
+toml = "*"
+
 [[package]]
 name = "wcwidth"
 version = "0.2.9"
@@ -2705,4 +2720,4 @@ testing = ["coverage (>=5.0.3)", "zope.event", "zope.testing"]
 [metadata]
 lock-version = "2.0"
 python-versions = ">=3.9, <4"
-content-hash = "e80cb6effd4fa79e5fcec4dd180dd1cbd87e9d75f81a12ec7352666f0a24c9b2"
+content-hash = "68a93e757577e3c200d3602ee078e2daeaa10a3423a3dd44c5e56cdfc0e85fb5"
diff --git a/pyproject.toml b/pyproject.toml
index 847a328b..1b8e9d4d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -97,6 +97,10 @@ redis = "^3.5.3"
 [tool.poetry.group.docs.dependencies]
 sphinx-rtd-theme = "^1.3.0"
 
+
+[tool.poetry.group.dev.dependencies]
+vulture = "^2.10"
+
 [tool.black]
 line-length = 88
 include = '\.pyi?$'