diff --git a/pyerrors/input/dobs.py b/pyerrors/input/dobs.py
index aea9b7a9..201bbff8 100644
--- a/pyerrors/input/dobs.py
+++ b/pyerrors/input/dobs.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 from collections import defaultdict
 import gzip
 import lxml.etree as et
@@ -11,10 +12,13 @@ from ..obs import Obs
 from ..obs import _merge_idx
 from ..covobs import Covobs
 from .. import version as pyerrorsversion
+from lxml.etree import _Element
+from numpy import ndarray
+from typing import Any, Dict, List, Optional, Tuple, Union
 
 
 # Based on https://stackoverflow.com/a/10076823
-def _etree_to_dict(t):
+def _etree_to_dict(t: _Element) -> Dict[str, Union[str, Dict[str, str], Dict[str, Union[str, Dict[str, str]]]]]:
     """ Convert the content of an XML file to a python dict"""
     d = {t.tag: {} if t.attrib else None}
     children = list(t)
@@ -38,7 +42,7 @@ def _etree_to_dict(t):
     return d
 
 
-def _dict_to_xmlstring(d):
+def _dict_to_xmlstring(d: Dict[str, Any]) -> str:
     if isinstance(d, dict):
         iters = ''
         for k in d:
@@ -66,7 +70,7 @@ def _dict_to_xmlstring(d):
     return iters
 
 
-def _dict_to_xmlstring_spaces(d, space='  '):
+def _dict_to_xmlstring_spaces(d: Dict[str, Dict[str, Dict[str, Union[str, Dict[str, str], List[Dict[str, str]]]]]], space: str='  ') -> str:
     s = _dict_to_xmlstring(d)
     o = ''
     c = 0
@@ -85,7 +89,7 @@ def _dict_to_xmlstring_spaces(d, space='  '):
     return o
 
 
-def create_pobs_string(obsl, name, spec='', origin='', symbol=[], enstag=None):
+def create_pobs_string(obsl: List[Obs], name: str, spec: str='', origin: str='', symbol: Optional[List[Union[str, Any]]]=None, enstag: None=None) -> str:
     """Export a list of Obs or structures containing Obs to an xml string
     according to the Zeuthen pobs format.
 
@@ -113,6 +117,8 @@ def create_pobs_string(obsl, name, spec='', origin='', symbol=[], enstag=None):
         XML formatted string of the input data
     """
 
+    if symbol is None:
+        symbol = []
     od = {}
     ename = obsl[0].e_names[0]
     names = list(obsl[0].deltas.keys())
@@ -176,7 +182,7 @@ def create_pobs_string(obsl, name, spec='', origin='', symbol=[], enstag=None):
     return rs
 
 
-def write_pobs(obsl, fname, name, spec='', origin='', symbol=[], enstag=None, gz=True):
+def write_pobs(obsl: List[Obs], fname: str, name: str, spec: str='', origin: str='', symbol: Optional[List[Union[str, Any]]]=None, enstag: None=None, gz: bool=True):
     """Export a list of Obs or structures containing Obs to a .xml.gz file
     according to the Zeuthen pobs format.
 
@@ -206,6 +212,8 @@ def write_pobs(obsl, fname, name, spec='', origin='', symbol=[], enstag=None, gz
     -------
     None
     """
+    if symbol is None:
+        symbol = []
     pobsstring = create_pobs_string(obsl, name, spec, origin, symbol, enstag)
 
     if not fname.endswith('.xml') and not fname.endswith('.gz'):
@@ -223,30 +231,30 @@ def write_pobs(obsl, fname, name, spec='', origin='', symbol=[], enstag=None, gz
     fp.close()
 
 
-def _import_data(string):
+def _import_data(string: str) -> List[Union[int, float]]:
     return json.loads("[" + ",".join(string.replace(' +', ' ').split()) + "]")
 
 
-def _check(condition):
+def _check(condition: bool):
     if not condition:
         raise Exception("XML file format not supported")
 
 
 class _NoTagInDataError(Exception):
     """Raised when tag is not in data"""
-    def __init__(self, tag):
+    def __init__(self, tag: str):
         self.tag = tag
         super().__init__('Tag %s not in data!' % (self.tag))
 
 
-def _find_tag(dat, tag):
+def _find_tag(dat: _Element, tag: str) -> int:
     for i in range(len(dat)):
         if dat[i].tag == tag:
             return i
     raise _NoTagInDataError(tag)
 
 
-def _import_array(arr):
+def _import_array(arr: _Element) -> Union[List[Union[str, List[int], List[ndarray]]], ndarray]:
     name = arr[_find_tag(arr, 'id')].text.strip()
     index = _find_tag(arr, 'layout')
     try:
@@ -284,12 +292,12 @@ def _import_array(arr):
         _check(False)
 
 
-def _import_rdata(rd):
+def _import_rdata(rd: _Element) -> Tuple[List[ndarray], str, List[int]]:
     name, idx, mask, deltas = _import_array(rd)
     return deltas, name, idx
 
 
-def _import_cdata(cd):
+def _import_cdata(cd: _Element) -> Tuple[str, ndarray, ndarray]:
     _check(cd[0].tag == "id")
     _check(cd[1][0].text.strip() == "cov")
     cov = _import_array(cd[1])
@@ -297,7 +305,7 @@ def _import_cdata(cd):
     return cd[0].text.strip(), cov, grad
 
 
-def read_pobs(fname, full_output=False, gz=True, separator_insertion=None):
+def read_pobs(fname: str, full_output: bool=False, gz: bool=True, separator_insertion: None=None) -> Union[Dict[str, Union[str, Dict[str, str], List[Obs]]], List[Obs]]:
     """Import a list of Obs from an xml.gz file in the Zeuthen pobs format.
 
     Tags are not written or recovered automatically.
@@ -309,7 +317,7 @@ def read_pobs(fname, full_output=False, gz=True, separator_insertion=None):
     full_output : bool
         If True, a dict containing auxiliary information and the data is returned.
         If False, only the data is returned as list.
-    separatior_insertion: str or int
+    separator_insertion: str or int
         str: replace all occurences of "separator_insertion" within the replica names
         by "|%s" % (separator_insertion) when constructing the names of the replica.
         int: Insert the separator "|" at the position given by separator_insertion.
@@ -397,7 +405,7 @@ def read_pobs(fname, full_output=False, gz=True, separator_insertion=None):
 
 
 # this is based on Mattia Bruno's implementation at https://github.com/mbruno46/pyobs/blob/master/pyobs/IO/xml.py
-def import_dobs_string(content, full_output=False, separator_insertion=True):
+def import_dobs_string(content: bytes, full_output: bool=False, separator_insertion: bool=True) -> Union[Dict[str, Union[str, Dict[str, str], List[Obs]]], List[Obs]]:
     """Import a list of Obs from a string in the Zeuthen dobs format.
 
     Tags are not written or recovered automatically.
@@ -409,7 +417,7 @@ def import_dobs_string(content, full_output=False, separator_insertion=True):
     full_output : bool
         If True, a dict containing auxiliary information and the data is returned.
         If False, only the data is returned as list.
-    separatior_insertion: str, int or bool
+    separator_insertion: str, int or bool
         str: replace all occurences of "separator_insertion" within the replica names
         by "|%s" % (separator_insertion) when constructing the names of the replica.
         int: Insert the separator "|" at the position given by separator_insertion.
@@ -571,7 +579,7 @@ def import_dobs_string(content, full_output=False, separator_insertion=True):
         return res
 
 
-def read_dobs(fname, full_output=False, gz=True, separator_insertion=True):
+def read_dobs(fname: str, full_output: bool=False, gz: bool=True, separator_insertion: bool=True) -> Union[Dict[str, Union[str, Dict[str, str], List[Obs]]], List[Obs]]:
     """Import a list of Obs from an xml.gz file in the Zeuthen dobs format.
 
     Tags are not written or recovered automatically.
@@ -618,7 +626,7 @@ def read_dobs(fname, full_output=False, gz=True, separator_insertion=True):
     return import_dobs_string(content, full_output, separator_insertion=separator_insertion)
 
 
-def _dobsdict_to_xmlstring(d):
+def _dobsdict_to_xmlstring(d: Dict[str, Any]) -> str:
     if isinstance(d, dict):
         iters = ''
         for k in d:
@@ -658,7 +666,7 @@ def _dobsdict_to_xmlstring(d):
     return iters
 
 
-def _dobsdict_to_xmlstring_spaces(d, space='  '):
+def _dobsdict_to_xmlstring_spaces(d: Dict[str, Union[Dict[str, Union[Dict[str, str], Dict[str, Union[str, Dict[str, str]]], Dict[str, Union[str, Dict[str, Union[str, List[str]]], List[Dict[str, Union[str, int, List[Dict[str, str]]]]]]]]], Dict[str, Union[Dict[str, str], Dict[str, Union[str, Dict[str, str]]], Dict[str, Union[str, Dict[str, Union[str, List[str]]], List[Dict[str, Union[str, int, List[Dict[str, str]]]]], List[Dict[str, Union[str, List[Dict[str, str]]]]]]]]]]], space: str='  ') -> str:
     s = _dobsdict_to_xmlstring(d)
     o = ''
     c = 0
@@ -677,7 +685,7 @@ def _dobsdict_to_xmlstring_spaces(d, space='  '):
     return o
 
 
-def create_dobs_string(obsl, name, spec='dobs v1.0', origin='', symbol=[], who=None, enstags=None):
+def create_dobs_string(obsl: List[Obs], name: str, spec: str='dobs v1.0', origin: str='', symbol: Optional[List[Union[str, Any]]]=None, who: None=None, enstags: Optional[Dict[Any, Any]]=None) -> str:
     """Generate the string for the export of a list of Obs or structures containing Obs
     to a .xml.gz file according to the Zeuthen dobs format.
 
@@ -708,6 +716,8 @@ def create_dobs_string(obsl, name, spec='dobs v1.0', origin='', symbol=[], who=N
     xml_str : str
         XML string generated from the data
     """
+    if symbol is None:
+        symbol = []
     if enstags is None:
         enstags = {}
     od = {}
@@ -866,7 +876,7 @@ def create_dobs_string(obsl, name, spec='dobs v1.0', origin='', symbol=[], who=N
     return rs
 
 
-def write_dobs(obsl, fname, name, spec='dobs v1.0', origin='', symbol=[], who=None, enstags=None, gz=True):
+def write_dobs(obsl: List[Obs], fname: str, name: str, spec: str='dobs v1.0', origin: str='', symbol: Optional[List[Union[str, Any]]]=None, who: None=None, enstags: None=None, gz: bool=True):
     """Export a list of Obs or structures containing Obs to a .xml.gz file
     according to the Zeuthen dobs format.
 
@@ -900,6 +910,8 @@ def write_dobs(obsl, fname, name, spec='dobs v1.0', origin='', symbol=[], who=No
     -------
     None
     """
+    if symbol is None:
+        symbol = []
     if enstags is None:
         enstags = {}
 
diff --git a/pyerrors/input/json.py b/pyerrors/input/json.py
index ca3fb0d2..2463959d 100644
--- a/pyerrors/input/json.py
+++ b/pyerrors/input/json.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 import rapidjson as json
 import gzip
 import getpass
@@ -12,9 +13,11 @@ from ..covobs import Covobs
 from ..correlators import Corr
 from ..misc import _assert_equal_properties
 from .. import version as pyerrorsversion
+from numpy import float32, float64, int64, ndarray
+from typing import Any, Dict, List, Optional, Tuple, Union
 
 
-def create_json_string(ol, description='', indent=1):
+def create_json_string(ol: Any, description: Union[str, Dict[str, Union[str, Dict[str, Union[Dict[str, Union[str, Dict[str, Union[int, str]]]], Dict[str, Optional[Union[str, List[str], float]]]]]]], Dict[str, Union[str, Dict[Optional[Union[int, bool]], str], float32]], Dict[str, Dict[str, Dict[str, str]]], Dict[str, Union[str, Dict[Optional[Union[int, bool]], str], Dict[int64, float64]]]]='', indent: int=1) -> str:
     """Generate the string for the export of a list of Obs or structures containing Obs
     to a .json(.gz) file
 
@@ -216,7 +219,7 @@ def create_json_string(ol, description='', indent=1):
         return json.dumps(d, indent=indent, ensure_ascii=False, default=_jsonifier, write_mode=json.WM_COMPACT)
 
 
-def dump_to_json(ol, fname, description='', indent=1, gz=True):
+def dump_to_json(ol: Union[Corr, List[Union[Obs, List[Obs], Corr, ndarray]], ndarray, List[Union[Obs, List[Obs], ndarray]], List[Obs]], fname: str, description: Union[str, Dict[str, Union[str, Dict[str, Union[Dict[str, Union[str, Dict[str, Union[int, str]]]], Dict[str, Optional[Union[str, List[str], float]]]]]]], Dict[str, Union[str, Dict[Optional[Union[int, bool]], str], float32]], Dict[str, Dict[str, Dict[str, str]]], Dict[str, Union[str, Dict[Optional[Union[int, bool]], str], Dict[int64, float64]]]]='', indent: int=1, gz: bool=True):
     """Export a list of Obs or structures containing Obs to a .json(.gz) file.
     Dict keys that are not JSON-serializable such as floats are converted to strings.
 
@@ -258,7 +261,7 @@ def dump_to_json(ol, fname, description='', indent=1, gz=True):
     fp.close()
 
 
-def _parse_json_dict(json_dict, verbose=True, full_output=False):
+def _parse_json_dict(json_dict: Dict[str, Any], verbose: bool=True, full_output: bool=False) -> Any:
     """Reconstruct a list of Obs or structures containing Obs from a dict that
     was built out of a json string.
 
@@ -470,7 +473,7 @@ def _parse_json_dict(json_dict, verbose=True, full_output=False):
         return ol
 
 
-def import_json_string(json_string, verbose=True, full_output=False):
+def import_json_string(json_string: str, verbose: bool=True, full_output: bool=False) -> Union[Obs, List[Obs], Corr]:
     """Reconstruct a list of Obs or structures containing Obs from a json string.
 
     The following structures are supported: Obs, list, numpy.ndarray, Corr
@@ -500,7 +503,7 @@ def import_json_string(json_string, verbose=True, full_output=False):
     return _parse_json_dict(json.loads(json_string), verbose, full_output)
 
 
-def load_json(fname, verbose=True, gz=True, full_output=False):
+def load_json(fname: str, verbose: bool=True, gz: bool=True, full_output: bool=False) -> Any:
     """Import a list of Obs or structures containing Obs from a .json(.gz) file.
 
     The following structures are supported: Obs, list, numpy.ndarray, Corr
@@ -545,7 +548,7 @@ def load_json(fname, verbose=True, gz=True, full_output=False):
     return _parse_json_dict(d, verbose, full_output)
 
 
-def _ol_from_dict(ind, reps='DICTOBS'):
+def _ol_from_dict(ind: Union[Dict[Optional[Union[int, bool]], str], Dict[str, Union[Dict[str, Union[Obs, List[Obs], Dict[str, Union[int, Obs, Corr, ndarray]]]], Dict[str, Optional[Union[str, List[str], Obs, float]]], str]], Dict[str, Union[Dict[str, Union[Obs, List[Obs], Dict[str, Union[int, Obs, Corr, ndarray]]]], Dict[str, Optional[Union[str, List[str], Obs, float]]], List[str]]], Dict[str, Union[Dict[str, Union[Obs, List[Obs], Dict[str, Union[int, Obs, Corr, ndarray]]]], Dict[str, Optional[Union[str, List[str], Obs, float]]]]]], reps: str='DICTOBS') -> Union[Tuple[List[Any], Dict[Optional[Union[int, bool]], str]], Tuple[List[Union[Obs, List[Obs], Corr, ndarray]], Dict[str, Union[Dict[str, Union[str, Dict[str, Union[int, str]]]], Dict[str, Optional[Union[str, List[str], float]]]]]]]:
     """Convert a dictionary of Obs objects to a list and a dictionary that contains
     placeholders instead of the Obs objects.
 
@@ -625,7 +628,7 @@ def _ol_from_dict(ind, reps='DICTOBS'):
     return ol, nd
 
 
-def dump_dict_to_json(od, fname, description='', indent=1, reps='DICTOBS', gz=True):
+def dump_dict_to_json(od: Union[Dict[str, Union[Dict[str, Union[Obs, List[Obs], Dict[str, Union[int, Obs, Corr, ndarray]]]], Dict[str, Optional[Union[str, List[str], Obs, float]]], str]], Dict[str, Union[Dict[str, Union[Obs, List[Obs], Dict[str, Union[int, Obs, Corr, ndarray]]]], Dict[str, Optional[Union[str, List[str], Obs, float]]], List[str]]], List[Union[Obs, List[Obs], Corr, ndarray]], Dict[Optional[Union[int, bool]], str], Dict[str, Union[Dict[str, Union[Obs, List[Obs], Dict[str, Union[int, Obs, Corr, ndarray]]]], Dict[str, Optional[Union[str, List[str], Obs, float]]]]]], fname: str, description: Union[str, float32, Dict[int64, float64]]='', indent: int=1, reps: str='DICTOBS', gz: bool=True):
     """Export a dict of Obs or structures containing Obs to a .json(.gz) file
 
     Parameters
@@ -665,7 +668,7 @@ def dump_dict_to_json(od, fname, description='', indent=1, reps='DICTOBS', gz=Tr
     dump_to_json(ol, fname, description=desc_dict, indent=indent, gz=gz)
 
 
-def _od_from_list_and_dict(ol, ind, reps='DICTOBS'):
+def _od_from_list_and_dict(ol: List[Union[Obs, List[Obs], Corr, ndarray]], ind: Dict[str, Dict[str, Optional[Union[str, Dict[str, Union[int, str]], List[str], float]]]], reps: str='DICTOBS') -> Dict[str, Dict[str, Any]]:
     """Parse a list of Obs or structures containing Obs and an accompanying
     dict, where the structures have been replaced by placeholders to a
     dict that contains the structures.
@@ -728,7 +731,7 @@ def _od_from_list_and_dict(ol, ind, reps='DICTOBS'):
     return nd
 
 
-def load_json_dict(fname, verbose=True, gz=True, full_output=False, reps='DICTOBS'):
+def load_json_dict(fname: str, verbose: bool=True, gz: bool=True, full_output: bool=False, reps: str='DICTOBS') -> Dict[str, Union[Dict[str, Union[Obs, List[Obs], Dict[str, Union[int, Obs, Corr, ndarray]]]], Dict[str, Optional[Union[str, List[str], Obs, float]]], str, Dict[str, Union[Dict[str, Union[Obs, List[Obs], Dict[str, Union[int, Obs, Corr, ndarray]]]], Dict[str, Optional[Union[str, List[str], Obs, float]]]]]]]:
     """Import a dict of Obs or structures containing Obs from a .json(.gz) file.
 
     The following structures are supported: Obs, list, numpy.ndarray, Corr
diff --git a/pyerrors/input/misc.py b/pyerrors/input/misc.py
index c62f502c..0c09b429 100644
--- a/pyerrors/input/misc.py
+++ b/pyerrors/input/misc.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 import os
 import fnmatch
 import re
@@ -8,9 +9,10 @@ import matplotlib.pyplot as plt
 from matplotlib import gridspec
 from ..obs import Obs
 from ..fits import fit_lin
+from typing import Dict, Optional
 
 
-def fit_t0(t2E_dict, fit_range, plot_fit=False, observable='t0'):
+def fit_t0(t2E_dict: Dict[float, Obs], fit_range: int, plot_fit: Optional[bool]=False, observable: str='t0') -> Obs:
     """Compute the root of (flow-based) data based on a dictionary that contains
     the necessary information in key-value pairs a la (flow time: observable at flow time).
 
diff --git a/pyerrors/input/openQCD.py b/pyerrors/input/openQCD.py
index 278977d2..6c23e3f2 100644
--- a/pyerrors/input/openQCD.py
+++ b/pyerrors/input/openQCD.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 import os
 import fnmatch
 import struct
@@ -8,9 +9,11 @@ from ..obs import CObs
 from ..correlators import Corr
 from .misc import fit_t0
 from .utils import sort_names
+from io import BufferedReader
+from typing import Dict, List, Optional, Tuple, Union
 
 
-def read_rwms(path, prefix, version='2.0', names=None, **kwargs):
+def read_rwms(path: str, prefix: str, version: str='2.0', names: Optional[List[str]]=None, **kwargs) -> List[Obs]:
     """Read rwms format from given folder structure. Returns a list of length nrw
 
     Parameters
@@ -229,7 +232,7 @@ def read_rwms(path, prefix, version='2.0', names=None, **kwargs):
     return result
 
 
-def _extract_flowed_energy_density(path, prefix, dtr_read, xmin, spatial_extent, postfix='ms', **kwargs):
+def _extract_flowed_energy_density(path: str, prefix: str, dtr_read: int, xmin: int, spatial_extent: int, postfix: str='ms', **kwargs) -> Dict[float, Obs]:
     """Extract a dictionary with the flowed Yang-Mills action density from given .ms.dat files.
     Returns a dictionary with Obs as values and flow times as keys.
 
@@ -422,7 +425,7 @@ def _extract_flowed_energy_density(path, prefix, dtr_read, xmin, spatial_extent,
     return E_dict
 
 
-def extract_t0(path, prefix, dtr_read, xmin, spatial_extent, fit_range=5, postfix='ms', c=0.3, **kwargs):
+def extract_t0(path: str, prefix: str, dtr_read: int, xmin: int, spatial_extent: int, fit_range: int=5, postfix: str='ms', c: Union[float, int]=0.3, **kwargs) -> Obs:
     """Extract t0/a^2 from given .ms.dat files. Returns t0 as Obs.
 
     It is assumed that all boundary effects have
@@ -495,7 +498,7 @@ def extract_t0(path, prefix, dtr_read, xmin, spatial_extent, fit_range=5, postfi
     return fit_t0(t2E_dict, fit_range, plot_fit=kwargs.get('plot_fit'))
 
 
-def extract_w0(path, prefix, dtr_read, xmin, spatial_extent, fit_range=5, postfix='ms', c=0.3, **kwargs):
+def extract_w0(path: str, prefix: str, dtr_read: int, xmin: int, spatial_extent: int, fit_range: int=5, postfix: str='ms', c: Union[float, int]=0.3, **kwargs) -> Obs:
     """Extract w0/a from given .ms.dat files. Returns w0 as Obs.
 
     It is assumed that all boundary effects have
@@ -577,7 +580,7 @@ def extract_w0(path, prefix, dtr_read, xmin, spatial_extent, fit_range=5, postfi
     return np.sqrt(fit_t0(tdtt2E_dict, fit_range, plot_fit=kwargs.get('plot_fit'), observable='w0'))
 
 
-def _parse_array_openQCD2(d, n, size, wa, quadrupel=False):
+def _parse_array_openQCD2(d: int, n: Tuple[int, int], size: int, wa: Union[Tuple[float, float, float, float, float, float, float, float], Tuple[float, float]], quadrupel: bool=False) -> List[List[float]]:
     arr = []
     if d == 2:
         for i in range(n[0]):
@@ -596,7 +599,7 @@ def _parse_array_openQCD2(d, n, size, wa, quadrupel=False):
     return arr
 
 
-def _find_files(path, prefix, postfix, ext, known_files=[]):
+def _find_files(path: str, prefix: str, postfix: str, ext: str, known_files: Union[str, List[str]]=[]) -> List[str]:
     found = []
     files = []
 
@@ -636,7 +639,7 @@ def _find_files(path, prefix, postfix, ext, known_files=[]):
     return files
 
 
-def _read_array_openQCD2(fp):
+def _read_array_openQCD2(fp: BufferedReader) -> Dict[str, Union[int, Tuple[int, int], List[List[float]]]]:
     t = fp.read(4)
     d = struct.unpack('i', t)[0]
     t = fp.read(4 * d)
@@ -662,7 +665,7 @@ def _read_array_openQCD2(fp):
     return {'d': d, 'n': n, 'size': size, 'arr': arr}
 
 
-def read_qtop(path, prefix, c, dtr_cnfg=1, version="openQCD", **kwargs):
+def read_qtop(path: str, prefix: str, c: float, dtr_cnfg: int=1, version: str="openQCD", **kwargs) -> Obs:
     """Read the topologial charge based on openQCD gradient flow measurements.
 
     Parameters
@@ -715,7 +718,7 @@ def read_qtop(path, prefix, c, dtr_cnfg=1, version="openQCD", **kwargs):
     return _read_flow_obs(path, prefix, c, dtr_cnfg=dtr_cnfg, version=version, obspos=0, **kwargs)
 
 
-def read_gf_coupling(path, prefix, c, dtr_cnfg=1, Zeuthen_flow=True, **kwargs):
+def read_gf_coupling(path: str, prefix: str, c: float, dtr_cnfg: int=1, Zeuthen_flow: bool=True, **kwargs) -> Obs:
     """Read the gradient flow coupling based on sfqcd gradient flow measurements. See 1607.06423 for details.
 
     Note: The current implementation only works for c=0.3 and T=L. The definition of the coupling in 1607.06423 requires projection to topological charge zero which is not done within this function but has to be performed in a separate step.
@@ -787,7 +790,7 @@ def read_gf_coupling(path, prefix, c, dtr_cnfg=1, Zeuthen_flow=True, **kwargs):
     return t * t * (5 / 3 * plaq - 1 / 12 * C2x1) / normdict[L]
 
 
-def _read_flow_obs(path, prefix, c, dtr_cnfg=1, version="openQCD", obspos=0, sum_t=True, **kwargs):
+def _read_flow_obs(path: str, prefix: str, c: float, dtr_cnfg: int=1, version: str="openQCD", obspos: int=0, sum_t: bool=True, **kwargs) -> Obs:
     """Read a flow observable based on openQCD gradient flow measurements.
 
     Parameters
@@ -1059,7 +1062,7 @@ def _read_flow_obs(path, prefix, c, dtr_cnfg=1, version="openQCD", obspos=0, sum
     return result
 
 
-def qtop_projection(qtop, target=0):
+def qtop_projection(qtop: Obs, target: int=0) -> Obs:
     """Returns the projection to the topological charge sector defined by target.
 
     Parameters
@@ -1085,7 +1088,7 @@ def qtop_projection(qtop, target=0):
     return reto
 
 
-def read_qtop_sector(path, prefix, c, target=0, **kwargs):
+def read_qtop_sector(path: str, prefix: str, c: float, target: int=0, **kwargs) -> Obs:
     """Constructs reweighting factors to a specified topological sector.
 
     Parameters
@@ -1143,7 +1146,7 @@ def read_qtop_sector(path, prefix, c, target=0, **kwargs):
     return qtop_projection(qtop, target=target)
 
 
-def read_ms5_xsf(path, prefix, qc, corr, sep="r", **kwargs):
+def read_ms5_xsf(path: str, prefix: str, qc: str, corr: str, sep: str="r", **kwargs) -> Corr:
     """
     Read data from files in the specified directory with the specified prefix and quark combination extension, and return a `Corr` object containing the data.
 
diff --git a/pyerrors/input/pandas.py b/pyerrors/input/pandas.py
index 13482983..f6cdb7bf 100644
--- a/pyerrors/input/pandas.py
+++ b/pyerrors/input/pandas.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 import warnings
 import gzip
 import sqlite3
@@ -6,9 +7,11 @@ from ..obs import Obs
 from ..correlators import Corr
 from .json import create_json_string, import_json_string
 import numpy as np
+from pandas.core.frame import DataFrame
+from pandas.core.series import Series
 
 
-def to_sql(df, table_name, db, if_exists='fail', gz=True, **kwargs):
+def to_sql(df: DataFrame, table_name: str, db: str, if_exists: str='fail', gz: bool=True, **kwargs):
     """Write DataFrame including Obs or Corr valued columns to sqlite database.
 
     Parameters
@@ -34,7 +37,7 @@ def to_sql(df, table_name, db, if_exists='fail', gz=True, **kwargs):
     con.close()
 
 
-def read_sql(sql, db, auto_gamma=False, **kwargs):
+def read_sql(sql: str, db: str, auto_gamma: bool=False, **kwargs) -> DataFrame:
     """Execute SQL query on sqlite database and obtain DataFrame including Obs or Corr valued columns.
 
     Parameters
@@ -58,7 +61,7 @@ def read_sql(sql, db, auto_gamma=False, **kwargs):
     return _deserialize_df(extract_df, auto_gamma=auto_gamma)
 
 
-def dump_df(df, fname, gz=True):
+def dump_df(df: DataFrame, fname: str, gz: bool=True):
     """Exports a pandas DataFrame containing Obs valued columns to a (gzipped) csv file.
 
     Before making use of pandas to_csv functionality Obs objects are serialized via the standardized
@@ -97,7 +100,7 @@ def dump_df(df, fname, gz=True):
         out.to_csv(fname, index=False)
 
 
-def load_df(fname, auto_gamma=False, gz=True):
+def load_df(fname: str, auto_gamma: bool=False, gz: bool=True) -> DataFrame:
     """Imports a pandas DataFrame from a csv.(gz) file in which Obs objects are serialized as json strings.
 
     Parameters
@@ -131,7 +134,7 @@ def load_df(fname, auto_gamma=False, gz=True):
     return _deserialize_df(re_import, auto_gamma=auto_gamma)
 
 
-def _serialize_df(df, gz=False):
+def _serialize_df(df: DataFrame, gz: bool=False) -> DataFrame:
     """Serializes all Obs or Corr valued columns into json strings according to the pyerrors json specification.
 
     Parameters
@@ -152,7 +155,7 @@ def _serialize_df(df, gz=False):
     return out
 
 
-def _deserialize_df(df, auto_gamma=False):
+def _deserialize_df(df: DataFrame, auto_gamma: bool=False) -> DataFrame:
     """Deserializes all pyerrors json strings into Obs or Corr objects according to the pyerrors json specification.
 
     Parameters
@@ -188,7 +191,7 @@ def _deserialize_df(df, auto_gamma=False):
     return df
 
 
-def _need_to_serialize(col):
+def _need_to_serialize(col: Series) -> bool:
     serialize = False
     i = 0
     while i < len(col) and col[i] is None:
diff --git a/pyerrors/input/sfcf.py b/pyerrors/input/sfcf.py
index e9f2837e..596a52e4 100644
--- a/pyerrors/input/sfcf.py
+++ b/pyerrors/input/sfcf.py
@@ -1,3 +1,4 @@
+from __future__ import annotations
 import os
 import fnmatch
 import re
@@ -5,12 +6,14 @@ import numpy as np  # Thinly-wrapped numpy
 from ..obs import Obs
 from .utils import sort_names, check_idl
 import itertools
+from numpy import ndarray
+from typing import Any, Dict, List, Tuple, Union
 
 
 sep = "/"
 
 
-def read_sfcf(path, prefix, name, quarks='.*', corr_type="bi", noffset=0, wf=0, wf2=0, version="1.0c", cfg_separator="n", silent=False, **kwargs):
+def read_sfcf(path: str, prefix: str, name: str, quarks: str='.*', corr_type: str="bi", noffset: int=0, wf: int=0, wf2: int=0, version: str="1.0c", cfg_separator: str="n", silent: bool=False, **kwargs) -> List[Obs]:
     """Read sfcf files from given folder structure.
 
     Parameters
@@ -75,7 +78,7 @@ def read_sfcf(path, prefix, name, quarks='.*', corr_type="bi", noffset=0, wf=0,
     return ret[name][quarks][str(noffset)][str(wf)][str(wf2)]
 
 
-def read_sfcf_multi(path, prefix, name_list, quarks_list=['.*'], corr_type_list=['bi'], noffset_list=[0], wf_list=[0], wf2_list=[0], version="1.0c", cfg_separator="n", silent=False, keyed_out=False, **kwargs):
+def read_sfcf_multi(path: str, prefix: str, name_list: List[str], quarks_list: List[str]=['.*'], corr_type_list: List[str]=['bi'], noffset_list: List[int]=[0], wf_list: List[int]=[0], wf2_list: List[int]=[0], version: str="1.0c", cfg_separator: str="n", silent: bool=False, keyed_out: bool=False, **kwargs) -> Dict[str, Dict[str, Dict[str, Dict[str, Dict[str, List[Obs]]]]]]:
     """Read sfcf files from given folder structure.
 
     Parameters
@@ -407,22 +410,22 @@ def read_sfcf_multi(path, prefix, name_list, quarks_list=['.*'], corr_type_list=
     return result_dict
 
 
-def _lists2key(*lists):
+def _lists2key(*lists) -> List[str]:
     keys = []
     for tup in itertools.product(*lists):
         keys.append(sep.join(tup))
     return keys
 
 
-def _key2specs(key):
+def _key2specs(key: str) -> List[str]:
     return key.split(sep)
 
 
-def _specs2key(*specs):
+def _specs2key(*specs) -> str:
     return sep.join(specs)
 
 
-def _read_o_file(cfg_path, name, needed_keys, intern, version, im):
+def _read_o_file(cfg_path: str, name: str, needed_keys: List[str], intern: Dict[str, Dict[str, Union[bool, Dict[str, Dict[str, Dict[str, Dict[str, Dict[str, Union[int, str]]]]]], int]]], version: str, im: int) -> Dict[str, List[float]]:
     return_vals = {}
     for key in needed_keys:
         file = cfg_path + '/' + name
@@ -447,7 +450,7 @@ def _read_o_file(cfg_path, name, needed_keys, intern, version, im):
     return return_vals
 
 
-def _extract_corr_type(corr_type):
+def _extract_corr_type(corr_type: str) -> Tuple[bool, bool]:
     if corr_type == 'bb':
         b2b = True
         single = True
@@ -460,7 +463,7 @@ def _extract_corr_type(corr_type):
     return b2b, single
 
 
-def _find_files(rep_path, prefix, compact, files=[]):
+def _find_files(rep_path: str, prefix: str, compact: bool, files: List[Union[range, str, Any]]=[]) -> List[str]:
     sub_ls = []
     if not files == []:
         files.sort(key=lambda x: int(re.findall(r'\d+', x)[-1]))
@@ -487,7 +490,7 @@ def _find_files(rep_path, prefix, compact, files=[]):
     return files
 
 
-def _make_pattern(version, name, noffset, wf, wf2, b2b, quarks):
+def _make_pattern(version: str, name: str, noffset: str, wf: str, wf2: Union[str, int], b2b: bool, quarks: str) -> str:
     if version == "0.0":
         pattern = "# " + name + " : offset " + str(noffset) + ", wf " + str(wf)
         if b2b:
@@ -501,7 +504,7 @@ def _make_pattern(version, name, noffset, wf, wf2, b2b, quarks):
     return pattern
 
 
-def _find_correlator(file_name, version, pattern, b2b, silent=False):
+def _find_correlator(file_name: str, version: str, pattern: str, b2b: bool, silent: bool=False) -> Tuple[int, int]:
     T = 0
 
     with open(file_name, "r") as my_file:
@@ -527,7 +530,7 @@ def _find_correlator(file_name, version, pattern, b2b, silent=False):
     return start_read, T
 
 
-def _read_compact_file(rep_path, cfg_file, intern, needed_keys, im):
+def _read_compact_file(rep_path: str, cfg_file: str, intern: Dict[str, Dict[str, Union[bool, Dict[str, Dict[str, Dict[str, Dict[str, Dict[str, Union[int, str]]]]]], int]]], needed_keys: List[str], im: int) -> Dict[str, List[float]]:
     return_vals = {}
     with open(rep_path + cfg_file) as fp:
         lines = fp.readlines()
@@ -558,7 +561,7 @@ def _read_compact_file(rep_path, cfg_file, intern, needed_keys, im):
     return return_vals
 
 
-def _read_compact_rep(path, rep, sub_ls, intern, needed_keys, im):
+def _read_compact_rep(path: str, rep: str, sub_ls: List[str], intern: Dict[str, Dict[str, Union[bool, Dict[str, Dict[str, Dict[str, Dict[str, Dict[str, Union[int, str]]]]]], int]]], needed_keys: List[str], im: int) -> Dict[str, List[ndarray]]:
     rep_path = path + '/' + rep + '/'
     no_cfg = len(sub_ls)
 
@@ -580,7 +583,7 @@ def _read_compact_rep(path, rep, sub_ls, intern, needed_keys, im):
     return return_vals
 
 
-def _read_chunk(chunk, gauge_line, cfg_sep, start_read, T, corr_line, b2b, pattern, im, single):
+def _read_chunk(chunk: List[str], gauge_line: int, cfg_sep: str, start_read: int, T: int, corr_line: int, b2b: bool, pattern: str, im: int, single: bool) -> Tuple[int, List[float]]:
     try:
         idl = int(chunk[gauge_line].split(cfg_sep)[-1])
     except Exception:
@@ -597,7 +600,7 @@ def _read_chunk(chunk, gauge_line, cfg_sep, start_read, T, corr_line, b2b, patte
     return idl, data
 
 
-def _read_append_rep(filename, pattern, b2b, cfg_separator, im, single):
+def _read_append_rep(filename: str, pattern: str, b2b: bool, cfg_separator: str, im: int, single: bool) -> Tuple[int, List[int], List[List[float]]]:
     with open(filename, 'r') as fp:
         content = fp.readlines()
         data_starts = []
@@ -646,7 +649,7 @@ def _read_append_rep(filename, pattern, b2b, cfg_separator, im, single):
         return T, rep_idl, data
 
 
-def _get_rep_names(ls, ens_name=None):
+def _get_rep_names(ls: List[str], ens_name: None=None) -> List[str]:
     new_names = []
     for entry in ls:
         try:
@@ -661,7 +664,7 @@ def _get_rep_names(ls, ens_name=None):
     return new_names
 
 
-def _get_appended_rep_names(ls, prefix, name, ens_name=None):
+def _get_appended_rep_names(ls: List[str], prefix: str, name: str, ens_name: None=None) -> List[str]:
     new_names = []
     for exc in ls:
         if not fnmatch.fnmatch(exc, prefix + '*.' + name):
diff --git a/pyerrors/input/utils.py b/pyerrors/input/utils.py
index eaf41f06..5ac00ba8 100644
--- a/pyerrors/input/utils.py
+++ b/pyerrors/input/utils.py
@@ -1,11 +1,13 @@
 """Utilities for the input"""
 
+from __future__ import annotations
 import re
 import fnmatch
 import os
+from typing import List
 
 
-def sort_names(ll):
+def sort_names(ll: List[str]) -> List[str]:
     """Sorts a list of names of replika with searches for `r` and `id` in the replikum string.
     If this search fails, a fallback method is used,
     where the strings are simply compared and the first diffeing numeral is used for differentiation.