diff --git a/index.json b/index.json
index ccf2fba6..293b49a7 100644
--- a/index.json
+++ b/index.json
@@ -130,6 +130,7 @@
     ]
   },
   "sidekiq-scheduler": {},
+  "simplecov": {},
   "state_machines": {},
   "stripe": {
     "skip_exported_rbis": true
diff --git a/rbi/annotations/simplecov.rbi b/rbi/annotations/simplecov.rbi
new file mode 100644
index 00000000..f51734c1
--- /dev/null
+++ b/rbi/annotations/simplecov.rbi
@@ -0,0 +1,46 @@
+# typed: true
+
+module SimpleCov
+  sig { returns(SimpleCov::FormatterInterface) }
+  attr_accesor :formatter
+
+  class << self
+    sig { params(profile: T.nilable(T.any(String, Symbol)), block: T.proc.bind(SimpleCov::Configuration).void).void }
+    def start(profile = nil, &block); end
+  end
+end
+
+# @shim: Not real at runtime, but describes the interface implemented by
+#   - https://github.com/simplecov-ruby/simplecov/blob/main/lib/simplecov/formatter/simple_formatter.rb
+#   - https://github.com/simplecov-ruby/simplecov/blob/main/lib/simplecov/formatter/multi_formatter.rb
+
+module SimpleCov::FormatterInterface
+  interface!
+
+  sig { abstract.params(result: SimpleCov::Result).returns(String) }
+  def format(result); end
+end
+
+class SimpleCov::Formatter::SimpleFormatter
+  include SimpleCov::FormatterInterface
+end
+
+class SimpleCov::Formatter::MultiFormatter
+  include SimpleCov::FormatterInterface
+end
+
+module SimpleCov::Configuration
+  # @shim: a String or Regexp that filters the file paths to be included in the coverage report
+  FilterSpec = T.type_alias { T.any(String, Regexp) }
+
+  sig do
+    params(
+      filter_argument: T.nilable(T.any(FilterSpec, T::Array[FilterSpec])),
+      filter_proc: T.nilable(T.proc.params(arg0: SimpleCov::SourceFile).returns(T::Boolean)),
+    ).void
+  end
+  def add_filter(filter_argument = nil, &filter_proc); end
+
+  sig { params(criterion: Symbol).void }
+  def enable_coverage(criterion); end
+end