diff --git a/services/api-server/pyproject.toml b/services/api-server/pyproject.toml
index cb4d1f2..44bae02 100644
--- a/services/api-server/pyproject.toml
+++ b/services/api-server/pyproject.toml
@@ -28,6 +28,7 @@ dependencies = [
   "sfera-ui-semantics",
   "smbprotocol>=1.15",
   "uvicorn>=0.30",
+  "python-multipart>=0.0.20",
 ]
 
 [tool.uv]
diff --git a/services/api-server/src/api_server/html5_forms.py b/services/api-server/src/api_server/html5_forms.py
index 138fe69..e49fc7b 100644
--- a/services/api-server/src/api_server/html5_forms.py
+++ b/services/api-server/src/api_server/html5_forms.py
@@ -6,6 +6,14 @@ from fastapi import Request
 
 
 async def html5_form_data(request: Request) -> dict[str, list[str]]:
+    content_type = request.headers.get("content-type", "")
+    if content_type.startswith("multipart/form-data"):
+        parsed = await request.form()
+        form: dict[str, list[str]] = {}
+        for key, value in parsed.multi_items():
+            text = getattr(value, "filename", None) if not isinstance(value, str) else value
+            form.setdefault(key, []).append(str(text or ""))
+        return form
     body = (await request.body()).decode("utf-8")
     return parse_qs(body, keep_blank_values=True)
 
diff --git a/services/api-server/tests/test_api.py b/services/api-server/tests/test_api.py
index ecce6b7..3215bac 100644
--- a/services/api-server/tests/test_api.py
+++ b/services/api-server/tests/test_api.py
@@ -484,6 +484,26 @@ def test_html5_project_index_creates_project_with_fragment():
     assert deleted_setup.json()["status"] == "NOT_CONFIGURED"
 
 
+def test_html5_project_create_accepts_multipart_browser_form():
+    client = TestClient(app)
+    project_id = f"html5-multipart-{uuid4()}"
+
+    created = client.post(
+        "/html5/projects",
+        files={
+            "project_id": (None, project_id),
+            "name": (None, "HTML5 Multipart"),
+        },
+    )
+
+    assert created.status_code == 200
+    assert_html5_response_contract(created, project_id, "HTML5 Multipart")
+
+    setup = client.get(f"/html5/projects/{project_id}/setup")
+    assert setup.status_code == 200
+    assert_html5_response_contract(setup, "data-html5-page=\"setup\"", "HTML5 Multipart", full_page=True)
+
+
 def test_html5_object_context_fragment(tmp_path: Path):
     project_id = f"html5-object-context-{uuid4()}"
     (tmp_path / "metadata.xml").write_text(
diff --git a/uv.lock b/uv.lock
index 4d4a075..709b949 100644
--- a/uv.lock
+++ b/uv.lock
@@ -505,6 +505,15 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/e5/35/f8b19922b6a25bc0880171a2f1a003eaeb93657475193ab516fd87cac9da/pytest_asyncio-1.3.0-py3-none-any.whl", hash = "sha256:611e26147c7f77640e6d0a92a38ed17c3e9848063698d5c93d5aa7aa11cebff5", size = 15075, upload-time = "2025-11-10T16:07:45.537Z" },
 ]
 
+[[package]]
+name = "python-multipart"
+version = "0.0.28"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/82/54/a85eb421fbdd5007bc5af39d0f4ed9fa609e0fedbfdc2adcf0b34526870e/python_multipart-0.0.28.tar.gz", hash = "sha256:8550da197eac0f7ab748961fc9509b999fa2662ea25cef857f05249f6893c0f8", size = 45314, upload-time = "2026-05-10T11:05:16.596Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/f3/a2/43bbc5860b5034e2af4ef99a0e04d726ff329c43e192ef3abaa8d7ecfce5/python_multipart-0.0.28-py3-none-any.whl", hash = "sha256:10faac07eb966c3f48dc415f9dee46c04cb10d58d30a35677db8027c825ed9b6", size = 29438, upload-time = "2026-05-10T11:05:15.052Z" },
+]
+
 [[package]]
 name = "pytz"
 version = "2026.2"
@@ -521,6 +530,7 @@ source = { editable = "services/api-server" }
 dependencies = [
     { name = "fastapi" },
     { name = "neo4j" },
+    { name = "python-multipart" },
     { name = "sfera-collaboration" },
     { name = "sfera-impact-engine" },
     { name = "sfera-incremental-indexer" },
@@ -550,6 +560,7 @@ dependencies = [
 requires-dist = [
     { name = "fastapi", specifier = ">=0.115" },
     { name = "neo4j", specifier = ">=5.0" },
+    { name = "python-multipart", specifier = ">=0.0.20" },
     { name = "sfera-collaboration", editable = "packages/collaboration" },
     { name = "sfera-impact-engine", editable = "packages/impact-engine" },
     { name = "sfera-incremental-indexer", editable = "packages/incremental-indexer" },