diff --git a/.gitignore b/.gitignore
index 3aa22dc..377c527 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,5 @@ forge_cache
 __pycache__
 *.kdev4
 config_local.sh
+.venv
+problems.json
diff --git a/verify.py b/verify.py
new file mode 100644
index 0000000..70b28d6
--- /dev/null
+++ b/verify.py
@@ -0,0 +1,93 @@
+#!/usr/bin/python3
+
+import datetime
+import hashlib
+import json
+from pathlib import Path
+
+import requests
+
+from metautil import *
+
+print("collecting artifacts")
+artifacts = set()
+
+for json_file in sorted(Path(f"multimc").glob("**/*.json")):
+    if json_file.name in ("index.json", "package.json"):
+        continue
+
+    version_file = MultiMCVersionFile(json.loads(json_file.read_text()))
+    libraries = list()
+    for key, value in version_file.items():
+        if isinstance(value, MultiMCLibrary):
+            libraries.append(value)
+        elif isinstance(value, list):
+            for entry in value:
+                if isinstance(entry, MultiMCLibrary):
+                    libraries.append(entry)
+
+    for library in libraries:
+        if not library.downloads:
+            url = library.url or "https://libraries.minecraft.net/"
+            if not url.endswith("/"):
+                url += "/"
+            url += library.name.getPath()
+            artifact = MojangArtifactBase({"url": url})
+            artifacts.add(json.dumps(artifact.to_json()))
+        else:
+            classifiers = library.downloads.classifiers or {}
+            for artifact in [library.downloads.artifact, *classifiers.values()]:
+                if artifact:
+                    artifacts.add(json.dumps(artifact.to_json()))
+
+artifacts = [MojangArtifact(json.loads(artifact)) for artifact in artifacts]
+artifacts.sort(key=lambda artifact: artifact.url)
+
+print(f"checking {len(artifacts)} artifacts")
+problems = list()
+problems_json = Path("problems.json")
+
+session = requests.session()
+i_max = len(artifacts)
+start = datetime.datetime.now().replace(microsecond=0)
+for i, artifact in enumerate(artifacts, start=1):
+    i = str(i).rjust(len(str(i_max)), "0")
+    runtime = datetime.datetime.now().replace(microsecond=0) - start
+    print(f"{runtime} {i}/{i_max} {artifact.url}")
+
+    if artifact.sha1 or artifact.size:
+        r = session.get(artifact.url, allow_redirects=True)
+    else:
+        r = session.head(artifact.url, allow_redirects=True)
+
+    artifact_problems = dict()
+    
+    if not r.ok:
+        artifact_problems["status"] = r.status_code
+
+    else:
+        if artifact.sha1:
+            sha1 = hashlib.sha1(r.content).hexdigest()
+            if artifact.sha1 != sha1:
+                artifact_problems["sha1"] = sha1
+
+        if artifact.size:
+            size = len(r.content)
+            if artifact.size != size:
+                artifact_problems["size"] = size
+    
+    if artifact_problems:
+        artifact_problems = {
+            "artifact": artifact.to_json(),
+            "problems": artifact_problems,
+        }
+        print(json.dumps(artifact_problems, indent=2))
+        problems.append(artifact_problems)
+        problems_json.write_text(json.dumps(problems, indent=2))
+
+if problems:
+    print(f"found {len(problems)} problems, check {problems_json}")
+else:
+    print("no problems found 🥳")
+    if problems_json.exists():
+        problems_json.unlink()