diff --git a/packages/slack/slack.0.1/opam b/packages/slack/slack.0.1/opam
new file mode 100644
index 000000000000..08f161a4354d
--- /dev/null
+++ b/packages/slack/slack.0.1/opam
@@ -0,0 +1,51 @@
+opam-version: "2.0"
+license: "MIT"
+maintainer: "Ahrefs <github@ahrefs.com>"
+authors: "Ahrefs <github@ahrefs.com>"
+homepage: "https://github.com/ahrefs/slack"
+bug-reports: "https://github.com/ahrefs/slack/issues"
+dev-repo: "git+https://github.com/ahrefs/slack.git"
+
+synopsis: "Slack API implementation"
+description: "OCaml interface for accessing Slack APIs and receiving events."
+
+depends: [
+  "dune" {>= "3.4"}
+  "atdgen" {> "2.0.0"}
+  "atdgen-runtime" {> "2.0.0"}
+  "biniou"
+  "cstruct"
+  "cmarkit"
+  "cmdliner"
+  "devkit" {>= "1.20210517" }
+  "extlib" {>= "1.7.7"}
+  "hex"
+  "lwt" {>= "5.1.0"}
+  "lwt_ppx"
+  "nocrypto"
+  "ppx_deriving"
+  "re2"
+  "uri"
+  "yojson"
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@doc" {with-doc}
+    "@runtest" {with-test}
+  ]
+]
+url {
+  src: "https://github.com/ahrefs/slack/archive/refs/tags/0.1.tar.gz"
+  checksum: [
+    "md5=f3be3accbb3b77babbc9b672746c603b"
+    "sha512=e715aa318eee97c65d254e1a2b052fb08a8e113d11343272c03a13cccd2f74a480678e064bcb6c901624aadcb83d16eabadbd6caa9181465a920cb69aee8f644"
+  ]
+}