diff --git a/src/execnet/_dictimport.py b/src/execnet/_dictimport.py
new file mode 100644
index 00000000..89f16789
--- /dev/null
+++ b/src/execnet/_dictimport.py
@@ -0,0 +1,98 @@
+# incomplete, to be completed later
+# this will replace concat based bootstrap
+from __future__ import annotations
+
+import base64
+import json
+import sys
+import types
+import zlib
+from importlib import import_module
+from importlib.abc import Loader
+from importlib.metadata import Distribution
+from importlib.metadata import DistributionFinder
+from typing import Any
+from typing import IO
+from typing import Iterable
+from typing import Sequence
+
+
+class DictImporter(DistributionFinder, Loader):
+    def __init__(self, sources: dict[str, str]):
+        self.sources = sources
+
+    def find_distributions(
+        self, context: DistributionFinder.Context = DistributionFinder.Context()
+    ) -> Iterable[Distribution]:
+        return []
+
+    def find_module(
+        self, fullname: str, path: Sequence[str | bytes] | None = None
+    ) -> Loader | None:
+        if fullname in self.sources:
+            return self
+        if fullname + ".__init__" in self.sources:
+            return self
+        return None
+
+    def load_module(self, fullname):
+        # print "load_module:",  fullname
+        from types import ModuleType
+
+        try:
+            s = self.sources[fullname]
+            is_pkg = False
+        except KeyError:
+            s = self.sources[fullname + ".__init__"]
+            is_pkg = True
+
+        co = compile(s, fullname, "exec")
+        module = sys.modules.setdefault(fullname, ModuleType(fullname))
+        module.__loader__ = self
+        if is_pkg:
+            module.__path__ = [fullname]
+
+        exec(co, module.__dict__)
+        return sys.modules[fullname]
+
+    def get_source(self, name: str) -> str | None:
+        res = self.sources.get(name)
+        if res is None:
+            res = self.sources.get(name + ".__init__")
+        return res
+
+
+def bootstrap(
+    modules: dict[str, str],
+    entry: str,
+    args: dict[str, Any],
+    set_argv: list[str] | None,
+) -> None:
+    importer = DictImporter(modules)
+    sys.meta_path.append(importer)
+    module, attr = entry.split(":")
+    loaded_module = import_module(module)
+    entry_func = getattr(loaded_module, entry)
+    if set_argv is not None:
+        sys.argv[1:] = set_argv
+    entry_func(**args)
+
+
+def bootstrap_stdin(stream: IO) -> None:
+    bootstrap_args = decode_b85_zip_json(stream.readline())
+    bootstrap(**bootstrap_args)
+
+
+def decode_b85_zip_json(encoded: bytes | str):
+    packed = base64.b85decode(encoded)
+    unpacked = zlib.decompress(packed)
+    return json.loads(unpacked)
+
+
+def naive_pack_module(module: types.ModuleType, dist: Distribution):
+    assert module.__file__ is not None
+    assert module.__path__
+
+
+if __name__ == "__main__":
+    bootstrap_stdin(sys.stdin)