diff --git a/my/arbtt.py b/my/arbtt.py
index 5683515..941a05f 100644
--- a/my/arbtt.py
+++ b/my/arbtt.py
@@ -23,7 +23,7 @@ def inputs() -> Sequence[Path]:
 
 
 from .core import dataclass, Json, PathIsh, datetime_aware
-from .core.common import isoparse
+from .core.compat import fromisoformat
 
 
 @dataclass
@@ -39,6 +39,7 @@ class Entry:
     @property
     def dt(self) -> datetime_aware:
         # contains utc already
+        # TODO after python>=3.11, could just use fromisoformat
         ds = self.json['date']
         elen = 27
         lds = len(ds)
@@ -46,10 +47,10 @@ class Entry:
             # ugh. sometimes contains less that 6 decimal points
             ds = ds[:-1] + '0' * (elen - lds) + 'Z'
         elif lds > elen:
-            # ahd sometimes more...
+            # and sometimes more...
             ds = ds[:elen - 1] + 'Z'
 
-        return isoparse(ds)
+        return fromisoformat(ds)
 
     @property
     def active(self) -> Optional[str]:
diff --git a/my/core/common.py b/my/core/common.py
index 85b9386..f1441a9 100644
--- a/my/core/common.py
+++ b/my/core/common.py
@@ -313,20 +313,18 @@ class classproperty(Generic[_R]):
 #     def __get__(self) -> _R:
 #         return self.f()
 
-# TODO deprecate in favor of datetime_aware
-tzdatetime = datetime
+# for now just serves documentation purposes... but one day might make it statically verifiable where possible?
+# TODO e.g. maybe use opaque mypy alias?
+datetime_naive = datetime
+datetime_aware = datetime
 
 
-# TODO doctests?
-def isoparse(s: str) -> tzdatetime:
-    """
-    Parses timestamps formatted like 2020-05-01T10:32:02.925961Z
-    """
-    # TODO could use dateutil? but it's quite slow as far as I remember..
-    # TODO support non-utc.. somehow?
-    assert s.endswith('Z'), s
-    s = s[:-1] + '+00:00'
-    return datetime.fromisoformat(s)
+# TODO deprecate
+tzdatetime = datetime_aware
+
+
+# TODO deprecate (although could be used in modules)
+from .compat import fromisoformat as isoparse
 
 
 import re
@@ -590,12 +588,6 @@ def asdict(thing: Any) -> Json:
     raise TypeError(f'Could not convert object {thing} to dict')
 
 
-# for now just serves documentation purposes... but one day might make it statically verifiable where possible?
-# TODO e.g. maybe use opaque mypy alias?
-datetime_naive = datetime
-datetime_aware = datetime
-
-
 def assert_subpackage(name: str) -> None:
     # can lead to some unexpected issues if you 'import cachew' which being in my/core directory.. so let's protect against it
     # NOTE: if we use overlay, name can be smth like my.origg.my.core.cachew ...
diff --git a/my/core/compat.py b/my/core/compat.py
index 48e194b..9cdea27 100644
--- a/my/core/compat.py
+++ b/my/core/compat.py
@@ -76,3 +76,42 @@ if sys.version_info[:2] <= (3, 9):
         return lo
 else:
     from bisect import bisect_left
+
+
+from datetime import datetime
+if sys.version_info[:2] >= (3, 11):
+    fromisoformat = datetime.fromisoformat
+else:
+    def fromisoformat(date_string: str) -> datetime:
+        # didn't support Z as "utc" before 3.11
+        if date_string.endswith('Z'):
+            # NOTE: can be removed from 3.11?
+            # https://docs.python.org/3/library/datetime.html#datetime.datetime.fromisoformat
+            date_string = date_string[:-1] + '+00:00'
+        return datetime.fromisoformat(date_string)
+
+
+def test_fromisoformat() -> None:
+    from datetime import timezone
+
+    # feedbin has this format
+    assert fromisoformat('2020-05-01T10:32:02.925961Z') == datetime(
+        2020, 5, 1, 10, 32, 2, 925961, timezone.utc,
+    )
+
+    # polar has this format
+    assert fromisoformat('2018-11-28T22:04:01.304Z') == datetime(
+        2018, 11, 28, 22, 4, 1, 304000, timezone.utc,
+    )
+
+    # stackexchange, runnerup has this format
+    assert fromisoformat('2020-11-30T00:53:12Z') == datetime(
+        2020, 11, 30, 0, 53, 12, 0, timezone.utc,
+    )
+
+    # arbtt has this format (sometimes less/more than 6 digits in milliseconds)
+    # TODO doesn't work atm, not sure if really should be supported...
+    # maybe should have flags for weird formats?
+    # assert isoparse('2017-07-18T18:59:38.21731Z') == datetime(
+    #     2017, 7, 18, 18, 59, 38, 217310, timezone.utc,
+    # )
diff --git a/my/core/query_range.py b/my/core/query_range.py
index afde933..dfb9e55 100644
--- a/my/core/query_range.py
+++ b/my/core/query_range.py
@@ -24,7 +24,7 @@ from .query import (
     ET,
 )
 
-from .common import isoparse
+from .compat import fromisoformat
 
 
 timedelta_regex = re.compile(r"^((?P<weeks>[\.\d]+?)w)?((?P<days>[\.\d]+?)d)?((?P<hours>[\.\d]+?)h)?((?P<minutes>[\.\d]+?)m)?((?P<seconds>[\.\d]+?)s)?$")
@@ -78,7 +78,7 @@ def parse_datetime_float(date_str: str) -> float:
     except ValueError:
         pass
     try:
-        return isoparse(ds).timestamp()
+        return fromisoformat(ds).timestamp()
     except (AssertionError, ValueError):
         pass
 
diff --git a/my/polar.py b/my/polar.py
index fe59d00..cd2c719 100644
--- a/my/polar.py
+++ b/my/polar.py
@@ -42,7 +42,7 @@ from typing import List, Dict, Iterable, NamedTuple, Sequence, Optional
 import json
 
 from .core import LazyLogger, Json, Res
-from .core.common import isoparse
+from .core.compat import fromisoformat
 from .core.error import echain, sort_res_by
 from .core.konsume import wrap, Zoomable, Wdict
 
@@ -145,7 +145,7 @@ class Loader:
             cmap[hlid] = ccs
             ccs.append(Comment(
                 cid=cid.value,
-                created=isoparse(crt.value),
+                created=fromisoformat(crt.value),
                 text=html.value, # TODO perhaps coonvert from html to text or org?
             ))
             v.consume()
@@ -183,7 +183,7 @@ class Loader:
 
             yield Highlight(
                 hid=hid,
-                created=isoparse(crt),
+                created=fromisoformat(crt),
                 selection=text,
                 comments=tuple(comments),
                 tags=tuple(htags),
@@ -221,7 +221,7 @@ class Loader:
         path = Path(config.polar_dir) / 'stash' / filename
 
         yield Book(
-            created=isoparse(added),
+            created=fromisoformat(added),
             uid=self.uid,
             path=path,
             title=title,
diff --git a/my/rss/feedbin.py b/my/rss/feedbin.py
index 8ba25b8..6160abc 100644
--- a/my/rss/feedbin.py
+++ b/my/rss/feedbin.py
@@ -7,7 +7,8 @@ from my.config import feedbin as config
 from pathlib import Path
 from typing import Sequence
 
-from ..core.common import listify, get_files, isoparse
+from ..core.common import listify, get_files
+from ..core.compat import fromisoformat
 from .common import Subscription
 
 
@@ -22,7 +23,7 @@ def parse_file(f: Path):
     raw = json.loads(f.read_text())
     for r in raw:
         yield Subscription(
-            created_at=isoparse(r['created_at']),
+            created_at=fromisoformat(r['created_at']),
             title=r['title'],
             url=r['site_url'],
             id=r['id'],
diff --git a/my/runnerup.py b/my/runnerup.py
index f12d9b3..ca09466 100644
--- a/my/runnerup.py
+++ b/my/runnerup.py
@@ -11,7 +11,8 @@ from pathlib import Path
 from typing import Iterable
 
 from .core import Res, get_files
-from .core.common import isoparse, Json
+from .core.common import Json
+from .core.compat import fromisoformat
 
 import tcxparser  # type: ignore[import-untyped]
 
@@ -44,7 +45,7 @@ def _parse(f: Path) -> Workout:
 
     return {
         'id'            : f.name, # not sure?
-        'start_time'    : isoparse(tcx.started_at),
+        'start_time'    : fromisoformat(tcx.started_at),
         'duration'      : timedelta(seconds=tcx.duration),
         'sport'         : sport,
         'heart_rate_avg': tcx.hr_avg,
@@ -58,7 +59,7 @@ def _parse(f: Path) -> Workout:
     #         tcx.hr_values(),
     #         # todo cadence?
     # ):
-    #     t = isoparse(ts)
+    #     t = fromisoformat(ts)
 
 
 def workouts() -> Iterable[Res[Workout]]:
diff --git a/my/stackexchange/gdpr.py b/my/stackexchange/gdpr.py
index 18b2b4d..2f3b98d 100644
--- a/my/stackexchange/gdpr.py
+++ b/my/stackexchange/gdpr.py
@@ -16,7 +16,8 @@ config = make_config(stackexchange)
 
 # TODO just merge all of them and then filter?.. not sure
 
-from ..core.common import Json, isoparse
+from ..core.common import Json
+from ..core.compat import fromisoformat
 from typing import NamedTuple, Iterable
 from datetime import datetime
 class Vote(NamedTuple):
@@ -25,7 +26,7 @@ class Vote(NamedTuple):
 
     @property
     def when(self) -> datetime:
-        return isoparse(self.j['eventTime'])
+        return fromisoformat(self.j['eventTime'])
 
     # todo Url return type?
     @property