diff --git a/README.md b/README.md
index 18c2bc25..0317eccd 100644
--- a/README.md
+++ b/README.md
@@ -361,9 +361,9 @@ for family, grp in itertools.groupby(collected.checks.items(), key=lambda x: x[1
 - [`GH211`](https://learn.scientific-python.org/development/guides/gha-basic#GH211): Do not pin core actions as major versions
 - [`GH212`](https://learn.scientific-python.org/development/guides/gha-basic#GH212): Require GHA update grouping
 
-### MyPy
+### Type checking
 
-- [`MY100`](https://learn.scientific-python.org/development/guides/style#MY100): Uses a type checker (pyproject config)
+- [`MY100`](https://learn.scientific-python.org/development/guides/style#MY100): Uses a type checker
 - [`MY101`](https://learn.scientific-python.org/development/guides/style#MY101): Type checker in strict mode
 - `MY102`: MyPy show_error_codes deprecated
 - [`MY103`](https://learn.scientific-python.org/development/guides/style#MY103): MyPy warn unreachable
diff --git a/docs/guides/index.md b/docs/guides/index.md
index 1a2727b9..89a5e420 100644
--- a/docs/guides/index.md
+++ b/docs/guides/index.md
@@ -9,7 +9,7 @@ for your `CONTRIBUTING.md`, and at least glance through other sections.
 
 Following that, there are recommendations for [style][], intended to promote
 good practices and to ensure continuity across the packages. There is a
-[dedicated page for static type checking with MyPy][mypy]. There are then
+[dedicated page for static type checking][typing]. There are then
 guides on [simple packaging][] and [compiled packaging][], which should help in
 ensuring a consistent developer and user experience when working with
 distribution.
@@ -38,7 +38,7 @@ WebAssembly! All checks point to a linked badge in the guide.
 
 [tutorials]:          /tutorials/index.md
 [style]:              /guides/style.md
-[mypy]:               /guides/typing.md
+[typing]:             /guides/typing.md
 [docs]:               /guides/docs.md
 [simple packaging]:   /guides/packaging_simple.md
 [compiled packaging]: /guides/packaging_compiled.md
diff --git a/docs/guides/style.md b/docs/guides/style.md
index 9ff4d0f1..f1b452a0 100644
--- a/docs/guides/style.md
+++ b/docs/guides/style.md
@@ -690,7 +690,9 @@ another.
 :::
 ::::
 
-These checkers read their configuration from `pyproject.toml`:
+These checkers read their configuration from `pyproject.toml`, shown below.
+Pyrefly and ty can also use a standalone `pyrefly.toml` or `ty.toml` file. In
+these files, drop the `tool.<name>` prefix from the table names.
 
 ::::{tab-set}
 :::{tab-item} MyPy
diff --git a/docs/guides/typing.md b/docs/guides/typing.md
index ead3d94a..b9a40d42 100644
--- a/docs/guides/typing.md
+++ b/docs/guides/typing.md
@@ -53,17 +53,53 @@ code also runs.
 
 ### Configuration
 
-By default, the type checker does as little as possible, so that you can add it
-iteratively to a code base. By default:
+The three main type checkers are [MyPy](https://mypy.readthedocs.io),
+[Pyrefly](https://pyrefly.org), and [ty](https://docs.astral.sh/ty/). They
+follow the same typing specification, but their defaults are different.
+
+Each checker reads configuration from `pyproject.toml`. Turn on as much
+checking as you can, and increase it over time. See the [style page][] for
+configuration suggestions for each checker.
+
+::::{tab-set}
+:::{tab-item} MyPy
+:sync: mypy
+MyPy does as little as possible by default, so that you can add it gradually
+to a code base:
 
 - All untyped variables and return values will be `Any`.
 - Code inside untyped functions is not checked _at all_.
 
-You can add configuration to `pyproject.toml` (and a little bit to the files
-themselves), or you can go all the way and pass `--strict`, which will turn on
-everything. Try to turn on as much as possible, and increase it until you can
-run with full `strict` checking. See the [style page][] for configuration
-suggestions.
+Set `strict = true` (or pass `--strict`) to turn on all checks. Disable MyPy on
+a line with `# type: ignore[error-code]`.
+:::
+:::{tab-item} Pyrefly
+:sync: pyrefly
+Pyrefly checks the bodies of all functions by default, including untyped ones.
+It also infers return types of unannotated functions, so it can find errors in
+code that has no annotations.
+
+Set `preset = "strict"` to turn on stricter checks. Configuration can also go
+in a `pyrefly.toml` file. Disable Pyrefly only on a line with `# pyrefly:
+ignore`. Note that pyrefly will try to read mypy's config if no pyrefly config
+is present.
+
+:::
+:::{tab-item} ty
+:sync: ty
+ty checks the bodies of all functions by default, including untyped ones. It
+also infers return types of unannotated functions, so it can find errors in
+code that has no annotations.
+
+There is no single strict switch. Set the severity of individual rules in
+`[tool.ty.rules]`. Configuration can also go in a `ty.toml` file. Disable ty
+only on a line with `# ty: ignore`.
+:::
+::::
+
+The checkers do not always agree, because each one implements the typing
+specification differently. If your library supports more than one checker, run
+each one in CI. All three support `# type: ignore`.
 
 [style page]: /guides/style.md
 
diff --git a/src/sp_repo_review/checks/mypy.py b/src/sp_repo_review/checks/mypy.py
index 4edcf315..14045515 100644
--- a/src/sp_repo_review/checks/mypy.py
+++ b/src/sp_repo_review/checks/mypy.py
@@ -1,30 +1,36 @@
 from __future__ import annotations
 
-__lazy_modules__ = ["typing"]
-
-from typing import Any
+from typing import TYPE_CHECKING, Any
 
 from . import mk_url
 
+if TYPE_CHECKING:
+    from importlib.resources.abc import Traversable
+
+MY100_CONFIG_FILES = ("ty.toml", "pyrefly.toml")
+
 
 class MyPy:
     family = "mypy"
 
 
 class MY100(MyPy):
-    "Uses a type checker (pyproject config)"
+    "Uses a type checker"
 
     requires = {"PY001"}
     url = mk_url("style")
 
     @staticmethod
-    def check(pyproject: dict[str, Any]) -> bool:
+    def check(pyproject: dict[str, Any], package: Traversable) -> bool:
         """
         Must have a `tool.mypy`, `tool.pyrefly`, or `tool.ty` section in
-        `pyproject.toml`. Other forms of configuration are not supported by
-        this check.
+        `pyproject.toml`, or a `ty.toml` or `pyrefly.toml` file. The other checks in this family only read
+        `pyproject.toml`.
         """
 
+        if any(package.joinpath(fn).is_file() for fn in MY100_CONFIG_FILES):
+            return True
+
         match pyproject:
             case {
                 "tool": {"mypy": object()} | {"pyrefly": object()} | {"ty": object()}
diff --git a/src/sp_repo_review/families.py b/src/sp_repo_review/families.py
index 2dbbf5c1..9e8011eb 100644
--- a/src/sp_repo_review/families.py
+++ b/src/sp_repo_review/families.py
@@ -122,7 +122,7 @@ def get_families(
             readme_note="Will not show up if using lefthook instead of pre-commit/prek.",
         ),
         "mypy": Family(
-            name="MyPy",
+            name="Type checking",
         ),
         "ruff": Family(
             name="Ruff",
diff --git a/src/sp_repo_review/files.py b/src/sp_repo_review/files.py
index fee824a5..a25f085f 100644
--- a/src/sp_repo_review/files.py
+++ b/src/sp_repo_review/files.py
@@ -26,6 +26,8 @@ def prefetch_package() -> set[str]:
         ".pre-commit-config.yaml",
         ".readthedocs.yml",
         "noxfile.py",
+        "ty.toml",
+        "pyrefly.toml",
         "ruff.toml",
         ".ruff.toml",
     }
diff --git a/tests/test_mypy.py b/tests/test_mypy.py
index 19994897..386c6c50 100644
--- a/tests/test_mypy.py
+++ b/tests/test_mypy.py
@@ -1,32 +1,35 @@
+from pathlib import Path
+
+import pytest
 from repo_review.testing import compute_check, toml_loads
 
 
-def test_my100_present():
+def test_my100_present(tmp_path: Path):
     toml = toml_loads("""
         [tool.mypy]
         strict = true
         """)
-    assert compute_check("MY100", pyproject=toml).result
+    assert compute_check("MY100", pyproject=toml, package=tmp_path).result
 
 
-def test_my100_pyrefly():
+def test_my100_pyrefly(tmp_path: Path):
     toml = toml_loads("""
         [tool.pyrefly]
         project-includes = ["src"]
         """)
-    assert compute_check("MY100", pyproject=toml).result
+    assert compute_check("MY100", pyproject=toml, package=tmp_path).result
 
 
-def test_my100_ty():
+def test_my100_ty(tmp_path: Path):
     toml = toml_loads("""
         [tool.ty.src]
         include = ["src"]
         """)
-    assert compute_check("MY100", pyproject=toml).result
+    assert compute_check("MY100", pyproject=toml, package=tmp_path).result
 
 
-def test_my100_missing():
-    assert not compute_check("MY100", pyproject={}).result
+def test_my100_missing(tmp_path: Path):
+    assert not compute_check("MY100", pyproject={}, package=tmp_path).result
 
 
 def test_my101_present_bool():
@@ -156,3 +159,9 @@ def test_my106_missing():
         enable_error_code = ["ignore-without-code", "redundant-expr"]
         """)
     assert not compute_check("MY106", pyproject=toml).result
+
+
+@pytest.mark.parametrize("name", ["ty.toml", "pyrefly.toml"])
+def test_my100_config_file(tmp_path: Path, name: str):
+    tmp_path.joinpath(name).touch()
+    assert compute_check("MY100", pyproject={}, package=tmp_path).result