diff --git a/tools/sbom/sbom_data.py b/tools/sbom/sbom_data.py
new file mode 100644
index 0000000..0c380f6
--- /dev/null
+++ b/tools/sbom/sbom_data.py
@@ -0,0 +1,120 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2023 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Define data classes that model SBOMs defined by SPDX. The data classes could be
+written out to different formats (tagvalue, JSON, etc) of SPDX with corresponding
+writer utilities.
+
+Rrefer to SPDX 2.3 spec: https://spdx.github.io/spdx-spec/v2.3/ and go/android-spdx for details of
+fields in each data class.
+"""
+
+from dataclasses import dataclass, field
+from typing import List
+
+SPDXID_DOC = 'SPDXRef-DOCUMENT'
+SPDXID_PRODUCT = 'SPDXRef-PRODUCT'
+SPDXID_PLATFORM = 'SPDXRef-PLATFORM'
+
+PACKAGE_NAME_PRODUCT = 'PRODUCT'
+PACKAGE_NAME_PLATFORM = 'PLATFORM'
+
+
+class PackageExternalRefCategory:
+  SECURITY = 'SECURITY'
+  PACKAGE_MANAGER = 'PACKAGE-MANAGER'
+  PERSISTENT_ID = 'PERSISTENT-ID'
+  OTHER = 'OTHER'
+
+
+class PackageExternalRefType:
+  cpe22Type = 'cpe22Type'
+  cpe23Type = 'cpe23Type'
+
+
+@dataclass
+class PackageExternalRef:
+  category: PackageExternalRefCategory
+  type: PackageExternalRefType
+  locator: str
+
+
+@dataclass
+class Package:
+  name: str
+  id: str
+  version: str = None
+  supplier: str = None
+  download_location: str = None
+  files_analyzed: bool = False
+  verification_code: str = None
+  file_ids: List[str] = field(default_factory=list)
+  external_refs: List[PackageExternalRef] = field(default_factory=list)
+
+
+@dataclass
+class File:
+  id: str
+  name: str
+  checksum: str
+
+
+class RelationshipType:
+  DESCRIBES = 'DESCRIBES'
+  VARIANT_OF = 'VARIANT_OF'
+  GENERATED_FROM = 'GENERATED_FROM'
+
+
+@dataclass
+class Relationship:
+  id1: str
+  relationship: RelationshipType
+  id2: str
+
+
+@dataclass
+class DocumentExternalReference:
+  id: str
+  uri: str
+  checksum: str
+
+
+@dataclass
+class Document:
+  name: str
+  namespace: str
+  id: str = SPDXID_DOC
+  describes: str = SPDXID_PRODUCT
+  creators: List[str] = field(default_factory=list)
+  created: str = None
+  external_refs: List[DocumentExternalReference] = field(default_factory=list)
+  packages: List[Package] = field(default_factory=list)
+  files: List[File] = field(default_factory=list)
+  relationships: List[Relationship] = field(default_factory=list)
+
+  def add_external_ref(self, external_ref):
+    if not any(external_ref.uri == ref.uri for ref in self.external_refs):
+      self.external_refs.append(external_ref)
+
+  def add_package(self, package):
+    if not any(package.id == p.id for p in self.packages):
+      self.packages.append(package)
+
+  def add_relationship(self, rel):
+    if not any(rel.id1 == r.id1 and rel.id2 == r.id2 and rel.relationship == r.relationship
+               for r in self.relationships):
+      self.relationships.append(rel)