diff --git a/docs/data.md b/docs/data.md
index e74d810cee9..06c4eca585c 100644
--- a/docs/data.md
+++ b/docs/data.md
@@ -58,6 +58,8 @@ The following ecosystems have vulnerabilities encoded in this format:
     ([CC0 1.0](https://github.com/haskell/security-advisories/blob/main/LICENSE.txt))
 -   [Ubuntu](https://github.com/canonical/ubuntu-security-notices)
     ([CC-BY-SA 4.0](https://github.com/canonical/ubuntu-security-notices/blob/main/LICENSE))
+-   [opam (OCaml package manager)](https://github.com/ocaml/security-advisories)
+    ([CC0 1.0](https://github.com/ocaml/security-advisories/blob/main/LICENSE.txt))
 
 ## Converted data
 
@@ -91,6 +93,7 @@ Between the data served in OSV and the data converted to OSV the following ecosy
 -   Maven
 -   npm
 -   NuGet
+-   opam (OCaml package manager)
 -   OSS-Fuzz
 -   Packagist
 -   Pub
diff --git a/osv/ecosystems/_ecosystems.py b/osv/ecosystems/_ecosystems.py
index f7cd436eca4..84dccdacc8f 100644
--- a/osv/ecosystems/_ecosystems.py
+++ b/osv/ecosystems/_ecosystems.py
@@ -24,6 +24,7 @@
 from .hex import Hex
 from .maven import Maven
 from .nuget import NuGet
+from .opam import Opam
 from .packagist import Packagist
 from .pub import Pub
 from .pypi import PyPI
@@ -55,6 +56,7 @@
     'MinimOS': APK,
     'npm': SemverEcosystem,
     'NuGet': NuGet,
+    'opam': Opam,
     'openEuler': RPM,
     'openSUSE': RPM,
     'Packagist': Packagist,
diff --git a/osv/ecosystems/opam.py b/osv/ecosystems/opam.py
new file mode 100644
index 00000000000..4adf27e6f12
--- /dev/null
+++ b/osv/ecosystems/opam.py
@@ -0,0 +1,50 @@
+"""OPAM ecosystem helper."""
+import requests
+import json
+
+from ..third_party.univers.debian import Version as DebianVersion
+from . import config
+from .ecosystems_base import EnumerableEcosystem, EnumerateError
+
+class Opam(EnumerableEcosystem):
+    """OPAM packages ecosystem"""
+    def _sort_key(self, version):
+        # OPAM uses debian versioning
+        if not DebianVersion.is_valid(version):
+            # If debian version is not valid, it is most likely an invalid fixed
+            # version then sort it to the last/largest element
+            return DebianVersion(9999999999, '9999999999')
+        return DebianVersion.from_string(version)
+
+    _REPO = 'https://api.github.com/repos/ocaml/opam-repository/contents/packages/'
+    _REPO_ARCHIVE = 'https://api.github.com/repos/ocaml/opam-repository-archive/contents/packages/'
+
+    def enumerate_versions(self,
+                           package,
+                           introduced,
+                           fixed=None,
+                           last_affected=None,
+                           limits=None):
+        """Enumerate versions."""
+        response = requests.get(
+            self._REPO + package, timeout=config.timeout)
+        archive_response = requests.get(
+            self._REPO_ARCHIVE + package, timeout=config.timeout)
+        if response.status_code == 404 and archive_response.status_code == 404:
+            raise EnumerateError(f'Package {package} not found')
+        if response.status_code != 200 and archive_response.status_code != 200:
+            raise RuntimeError(
+                f'Failed to get OPAM versions for {package} with: {response.text}')
+
+        responses = {}
+
+        if response.status_code == 200:
+            responses.extend(response.json())
+        if archive_response.status_code == 200:
+            responses.extend(archive_response.json())
+
+        versions = [x["name"] for x in responses]
+
+        self.sort_versions(versions)
+        return self._get_affected_versions(versions, introduced, fixed,
+                                           last_affected, limits)
diff --git a/osv/purl_helpers.py b/osv/purl_helpers.py
index a44be1b8bb0..02a53a60d6f 100644
--- a/osv/purl_helpers.py
+++ b/osv/purl_helpers.py
@@ -70,6 +70,8 @@
         EcosystemPURL('npm', None),
     'NuGet':
         EcosystemPURL('nuget', None),
+    'opam':
+        EcosystemPURL('opam', None),
     'openEuler':
         EcosystemPURL('rpm', 'openeuler'),
     'openSUSE':