diff --git a/README.md b/README.md
index e8ff6115..3c5b6dbd 100644
--- a/README.md
+++ b/README.md
@@ -68,7 +68,7 @@ The following source and target combinations can be used:
 
 ### Validate
 
-This command runs a validation against a metadata csv file. It generates a STAC object on the fly for each metadata and run a JSON schema validation. It outputs the errors and their recurrences grouped by JSON schemas as:
+This command runs a validation against a metadata csv file. It generates the corresponding STAC objects on the fly for each metadata and run a JSON schema validation (using [jsonschema-rs](https://github.com/Stranger6667/jsonschema-rs)) for the `Items` and `Collections`. It outputs the errors and their recurrences grouped by JSON schemas as:
 ```json
 "errors": {"https://linz.github.io/stac/v0.0.7/aerial-photo/schema.json": {"'aerial-photo:run' is a required property": 4, "'aerial-photo:sequence_number' is a required property": 10}
 ```
@@ -78,6 +78,16 @@ This command runs a validation against a metadata csv file. It generates a STAC
 ./validate --source metadata_file.csv
 ```
 
+```shell
+# Run against the `Items` only:
+./validate --source metadata_file.csv --item
+```
+
+```shell
+# Run against the `Collections` only:
+./validate --source metadata_file.csv --collection
+```
+
 ```shell
 # For help:
 ./validate --help
diff --git a/topo_processor/cli/tests/main_test.py b/topo_processor/cli/tests/upload_test.py
similarity index 100%
rename from topo_processor/cli/tests/main_test.py
rename to topo_processor/cli/tests/upload_test.py
diff --git a/topo_processor/cli/main.py b/topo_processor/cli/upload.py
similarity index 100%
rename from topo_processor/cli/main.py
rename to topo_processor/cli/upload.py
diff --git a/topo_processor/cli/validate.py b/topo_processor/cli/validate.py
index 8498daf9..edac0b67 100644
--- a/topo_processor/cli/validate.py
+++ b/topo_processor/cli/validate.py
@@ -4,7 +4,7 @@
 from linz_logger import LogLevel, get_log, set_level
 
 from topo_processor.file_system.get_fs import is_s3_path
-from topo_processor.stac.item_factory import process_metadata
+from topo_processor.stac.validation import validate_stac
 from topo_processor.util import time_in_ms
 
 
@@ -19,9 +19,21 @@
     "-v",
     "--verbose",
     is_flag=True,
-    help="Use verbose to display trace logs",
+    help="Use verbose to display trace logs (it might be slower)",
 )
-def main(source, verbose):
+@click.option(
+    "-i",
+    "--item",
+    is_flag=True,
+    help="Use item to validate items only",
+)
+@click.option(
+    "-c",
+    "--collection",
+    is_flag=True,
+    help="Use collection to validate collections only",
+)
+def main(source, verbose, item, collection):
     if verbose:
         set_level(LogLevel.trace)
     else:
@@ -32,7 +44,11 @@ def main(source, verbose):
     if not is_s3_path(source):
         source = os.path.abspath(source)
 
-    process_metadata(source)
+    if item == collection:
+        validate_stac(source)
+    else:
+        validate_stac(source, item, collection)
+
     get_log().debug(
         "validate completed",
         file=source,
diff --git a/topo_processor/metadata/metadata_validators/metadata_validator_stac.py b/topo_processor/metadata/metadata_validators/metadata_validator_stac.py
index f5fce31f..cb0ff67d 100644
--- a/topo_processor/metadata/metadata_validators/metadata_validator_stac.py
+++ b/topo_processor/metadata/metadata_validators/metadata_validator_stac.py
@@ -2,16 +2,15 @@
 
 import json
 import urllib
-from typing import TYPE_CHECKING, Any, Dict
+from typing import TYPE_CHECKING, Any, Dict, Union
 
 import jsonschema_rs
 from linz_logger import get_log
 from pystac.errors import STACValidationError
 
-from .metadata_validator import MetadataValidator
+from topo_processor.stac import Collection, Item
 
-if TYPE_CHECKING:
-    from topo_processor.stac import Item
+from .metadata_validator import MetadataValidator
 
 
 class MetadataValidatorStac(MetadataValidator):
@@ -28,7 +27,7 @@ def get_validator_from_uri(self, schema_uri: str) -> Any:
 
         return validator
 
-    def is_applicable(self, item: Item) -> bool:
+    def is_applicable(self, stac_object: Union[Item, Collection]) -> bool:
         return True
 
     def validate_metadata(self, item: Item) -> None:
@@ -38,23 +37,27 @@ def validate_metadata(self, item: Item) -> None:
         except STACValidationError as e:
             raise STACValidationError(message=f"Not valid STAC: {e}")
 
-    def validate_metadata_with_report(self, item: Item) -> Dict[str, list[str]]:
+    def validate_metadata_with_report(self, stac_object: Union[Item, Collection]) -> Dict[str, list[str]]:
+        """Validate the STAC object (Item or Collection) against the core json schema and its extensions.
+        Return an error report [{schemaURI, [errors]}]
+        """
         errors_report: Dict[str, list[str]] = {}
-        stac_item = item.create_stac().to_dict(include_self_link=False)
-        schema_uris: list[str] = [item.schema] + stac_item["stac_extensions"]
+        stac_dict = stac_object.create_stac().to_dict(include_self_link=False)
+        # FIXME: Work around pystac `to_dict` serialization issue with links (https://github.com/stac-utils/pystac/issues/652)
+        if stac_dict["type"] == "Collection":
+            stac_dict["links"] = json.loads(json.dumps(stac_dict["links"]))
 
-        get_log().debug(f"{self.name}:validate_metadata_with_report", itemId=stac_item["id"])
+        schema_uris: list[str] = [stac_object.schema] + stac_dict["stac_extensions"]
 
         for schema_uri in schema_uris:
-            get_log().trace(f"{self.name}:validate_metadata_with_report", schema=schema_uri)
+            get_log().trace(f"{self.name}:validate_metadata_with_report", stacId=stac_dict["id"], schema=schema_uri)
             current_errors = []
             v = self.get_validator_from_uri(schema_uri)
-
-            errors = v.iter_errors(stac_item)
+            errors = v.iter_errors(stac_dict)
 
             for error in errors:
                 current_errors.append(error.message)
-                get_log().warn(f"{self.name}:validate_metadata_with_report", itemId=stac_item["id"], error=error.message)
+                get_log().warn(f"{self.name}:validate_metadata_with_report", stacId=stac_dict["id"], error=error.message)
 
             if current_errors:
                 errors_report[schema_uri] = current_errors
diff --git a/topo_processor/metadata/metadata_validators/tests/metadata_validator_stac_test.py b/topo_processor/metadata/metadata_validators/tests/metadata_validator_stac_test.py
index 01acc44f..ff745e00 100644
--- a/topo_processor/metadata/metadata_validators/tests/metadata_validator_stac_test.py
+++ b/topo_processor/metadata/metadata_validators/tests/metadata_validator_stac_test.py
@@ -7,6 +7,7 @@
 
 import topo_processor.stac as stac
 from topo_processor.metadata.metadata_validators.metadata_validator_stac import MetadataValidatorStac
+from topo_processor.stac.validate_report import ValidateReport
 
 
 def test_check_validity_camera_extension():
@@ -89,9 +90,9 @@ def test_check_validity_scanning_extension():
         validator.validate_metadata(item)
 
 
-def test_validate_metadata_with_report():
-    """check that the method return a report of the errors"""
-    errors_report: Dict[str, list] = {}
+def test_validate_metadata_with_report_item():
+    """check that the method return a report of the errors for an item validation"""
+    validate_report: ValidateReport = ValidateReport()
     source_path = os.path.join(os.getcwd(), "test_data", "tiffs", "SURVEY_1", "CONTROL.tiff")
     asset = stac.Asset(source_path)
     item = stac.Item("item_id")
@@ -107,6 +108,23 @@ def test_validate_metadata_with_report():
     item.add_extension(stac.StacExtensions.aerial_photo.value)
     validator = MetadataValidatorStac()
     assert validator.is_applicable(item)
-    errors_report = validator.validate_metadata_with_report(item)
-    assert '"string" is not of type "integer"' in errors_report[stac.StacExtensions.film.value]
-    assert '"aerial-photo:run" is a required property' in errors_report[stac.StacExtensions.aerial_photo.value]
+    validate_report.add_errors(validator.validate_metadata_with_report(item))
+    assert '"string" is not of type "integer"' in validate_report.report_per_error_type[stac.StacExtensions.film.value]
+    assert (
+        '"aerial-photo:run" is a required property'
+        in validate_report.report_per_error_type[stac.StacExtensions.aerial_photo.value]
+    )
+
+
+def test_validate_metadata_with_report_collection():
+    """check that the method return a report of the errors for a collection validation"""
+    """check that the method return a report of the errors for an item validation"""
+    validate_report: ValidateReport = ValidateReport()
+    collection = stac.Collection("title_col")
+    collection.description = "desc"
+    collection.license = "lic"
+    validator = MetadataValidatorStac()
+    assert validator.is_applicable(collection)
+    validate_report.add_errors(validator.validate_metadata_with_report(collection))
+    assert validate_report.total == 1
+    assert not validate_report.report_per_error_type
diff --git a/topo_processor/stac/__init__.py b/topo_processor/stac/__init__.py
index 81dcba53..946de642 100644
--- a/topo_processor/stac/__init__.py
+++ b/topo_processor/stac/__init__.py
@@ -5,3 +5,5 @@
 from .item_factory import process_directory
 from .stac_extensions import StacExtensions
 from .store import collection_store
+from .validate_report import ValidateReport
+from .validation import validate_stac
diff --git a/topo_processor/stac/collection.py b/topo_processor/stac/collection.py
index 5dab9d10..f3293f1f 100644
--- a/topo_processor/stac/collection.py
+++ b/topo_processor/stac/collection.py
@@ -6,9 +6,10 @@
 from tempfile import mkdtemp
 from typing import TYPE_CHECKING, Dict, List
 
-import pystac
 import ulid
 from linz_logger import get_log
+from pystac import pystac
+from pystac.validation.schema_uri_map import DefaultSchemaUriMap
 from shapely.ops import unary_union
 
 from topo_processor.util import Validity
@@ -21,17 +22,22 @@
 
 
 class Collection(Validity):
+    id: str
     title: str
     description: str
     license: str
     items: Dict[str, "Item"]
     providers: List[pystac.Provider]
+    schema: str
     stac_extensions: set
 
     def __init__(self, title: str):
         super().__init__()
+        # FIXME: Do we want to generate this id like this?
+        self.id = str(ulid.ULID())
         self.title = title
         self.items = {}
+        self.schema = DefaultSchemaUriMap().get_object_schema_uri(pystac.STACObjectType.COLLECTION, pystac.get_stac_version())
         self.stac_extensions = set([])
 
     def add_item(self, item: Item):
@@ -95,7 +101,7 @@ def delete_temp_dir(self):
 
     def create_stac(self) -> pystac.Collection:
         stac = pystac.Collection(
-            id=str(ulid.ULID()),
+            id=self.id,
             description=self.description,
             extent=pystac.Extent(
                 pystac.SpatialExtent(bboxes=self.get_bounding_boxes()),
diff --git a/topo_processor/stac/item_factory.py b/topo_processor/stac/item_factory.py
index b95a55a3..b03b0152 100644
--- a/topo_processor/stac/item_factory.py
+++ b/topo_processor/stac/item_factory.py
@@ -1,12 +1,10 @@
-from typing import Dict
-
 from linz_logger import get_log
 
 from topo_processor.data.data_transformers import data_transformer_repo
 from topo_processor.file_system.get_fs import get_fs
 from topo_processor.file_system.get_path_with_protocol import get_path_with_protocol
-from topo_processor.metadata.metadata_loaders import metadata_loader_imagery_historic, metadata_loader_repo
-from topo_processor.metadata.metadata_validators import metadata_validator_repo, metadata_validator_stac
+from topo_processor.metadata.metadata_loaders import metadata_loader_repo
+from topo_processor.metadata.metadata_validators import metadata_validator_repo
 from topo_processor.stac.store import get_asset, item_store
 from topo_processor.util import time_in_ms
 
@@ -19,42 +17,6 @@ def process_directory(source_dir: str) -> None:
     get_log().debug("Items Created", source_dir=source_dir, duration=time_in_ms() - start_time)
 
 
-def process_metadata(metadata_file: str) -> None:
-    start_time = time_in_ms()
-    errors_per_item: Dict[str, Dict[str, list]] = {}
-    errors_per_type: Dict[str, Dict[str, int]] = {}
-    total_items_processed = 0
-
-    # Load metadata from metadata csv file
-    metadata_loader_imagery_historic.load_all_metadata(metadata_file)
-    get_log().debug("Metadata Loaded", metadata_file=metadata_file, duration=time_in_ms() - start_time)
-
-    # Validate item against schema
-    for item in item_store.values():
-        if item.is_valid():
-            errors_per_item[item.id] = metadata_validator_stac.validate_metadata_with_report(item)
-            total_items_processed = total_items_processed + 1
-
-    # Build errors report
-    for errors_item in errors_per_item.values():
-        for schema_uri in errors_item:
-            if schema_uri not in errors_per_type:
-                errors_per_type[schema_uri] = {}
-            for error in errors_item[schema_uri]:
-                if error in errors_per_type[schema_uri]:
-                    errors_per_type[schema_uri][error] = errors_per_type[schema_uri][error] + 1
-                else:
-                    errors_per_type[schema_uri][error] = 1
-
-    get_log().info(
-        "Metadata Validated",
-        metadata_file=metadata_file,
-        nbItemsProcessed=total_items_processed,
-        duration=time_in_ms() - start_time,
-        errors=errors_per_type,
-    )
-
-
 def _create_assets(source_dir: str) -> None:
     fs = get_fs(source_dir)
     for (path, _, files) in fs.walk(source_dir):
diff --git a/topo_processor/stac/tests/validate_report_test.py b/topo_processor/stac/tests/validate_report_test.py
new file mode 100644
index 00000000..0ec6f77c
--- /dev/null
+++ b/topo_processor/stac/tests/validate_report_test.py
@@ -0,0 +1,19 @@
+import os
+from logging import error
+
+import pytest
+
+from topo_processor.stac.validate_report import ValidateReport
+
+
+def test_increment_error():
+    """"""
+    error_report: ValidateReport = ValidateReport()
+    error_report.increment_error("schema_a", "error_1")
+    assert error_report.report_per_error_type["schema_a"]["error_1"] == 1
+    error_report.increment_error("schema_a", "error_1")
+    assert error_report.report_per_error_type["schema_a"]["error_1"] == 2
+    error_report.increment_error("schema_b", "error_1")
+    assert error_report.report_per_error_type["schema_b"]["error_1"] == 1
+    error_report.increment_error("schema_a", "error_2")
+    assert error_report.report_per_error_type["schema_a"]["error_2"] == 1
diff --git a/topo_processor/stac/validate_report.py b/topo_processor/stac/validate_report.py
new file mode 100644
index 00000000..3371280e
--- /dev/null
+++ b/topo_processor/stac/validate_report.py
@@ -0,0 +1,22 @@
+from typing import Dict, List
+
+
+class ValidateReport:
+    total: int
+    report_per_error_type: Dict[str, Dict[str, int]]
+
+    def __init__(self):
+        self.total = 0
+        self.report_per_error_type = {}
+
+    def add_errors(self, errors_per_schema: Dict[str, List[str]]) -> None:
+        for schema_uri in errors_per_schema:
+            for error in errors_per_schema[schema_uri]:
+                self.increment_error(schema_uri, error)
+        self.total = self.total + 1
+
+    def increment_error(self, schema: str, error: str) -> None:
+        existing = self.report_per_error_type.get(schema)
+        if existing is None:
+            self.report_per_error_type[schema] = existing = {}
+        existing[error] = existing.get(error, 0) + 1
diff --git a/topo_processor/stac/validation.py b/topo_processor/stac/validation.py
new file mode 100644
index 00000000..fd7f4d2a
--- /dev/null
+++ b/topo_processor/stac/validation.py
@@ -0,0 +1,49 @@
+from typing import Any, Dict, List, Tuple, Union
+
+from linz_logger import get_log
+
+from topo_processor.metadata.metadata_loaders import metadata_loader_imagery_historic
+from topo_processor.metadata.metadata_validators import metadata_validator_stac
+from topo_processor.stac.validate_report import ValidateReport
+from topo_processor.util import time_in_ms
+
+from .collection import Collection
+from .item import Item
+from .store import collection_store, item_store
+
+
+def validate_stac(metadata_file: str, validate_item: bool = True, validate_collection: bool = True) -> None:
+    start_time = time_in_ms()
+    item_report: ValidateReport = ValidateReport()
+    collection_report: ValidateReport = ValidateReport()
+
+    # Load metadata from metadata csv file
+    metadata_loader_imagery_historic.load_all_metadata(metadata_file)
+    get_log().debug("Metadata Loaded", metadata_file=metadata_file, duration=time_in_ms() - start_time)
+
+    # Validate metadata from stored STAC objects
+    if validate_item:
+        item_report = validate_store(item_store)
+    if validate_collection:
+        collection_report = validate_store(collection_store)
+
+    # Print report
+    get_log().info(
+        "Metadata Validated",
+        metadata_file=metadata_file,
+        nbItemsValidated=item_report.total,
+        nbCollectionsValidated=collection_report.total,
+        duration=time_in_ms() - start_time,
+        itemErrors=item_report.report_per_error_type,
+        collectionErrors=collection_report.report_per_error_type,
+    )
+
+
+def validate_store(store: List[Union[Item, Collection]]) -> ValidateReport:
+    validate_report: ValidateReport = ValidateReport()
+
+    for stac_object in store.values():
+        if stac_object.is_valid():
+            validate_report.add_errors(metadata_validator_stac.validate_metadata_with_report(stac_object))
+
+    return validate_report
diff --git a/upload b/upload
index 852ed632..5bcda4c8 100755
--- a/upload
+++ b/upload
@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
 
-from topo_processor.cli import main
+from topo_processor.cli import upload
 
-main.main()
+upload.main()