diff --git a/packages/lwt/lwt.4.3.0/opam b/packages/lwt/lwt.4.3.0/opam
new file mode 100644
index 00000000000..0d4e756e502
--- /dev/null
+++ b/packages/lwt/lwt.4.3.0/opam
@@ -0,0 +1,64 @@
+opam-version: "2.0"
+
+synopsis: "Promises and event-driven I/O"
+
+version: "4.3.0"
+license: "MIT"
+homepage: "https://github.com/ocsigen/lwt"
+doc: "https://ocsigen.org/lwt/manual/"
+bug-reports: "https://github.com/ocsigen/lwt/issues"
+
+authors: [
+  "Jérôme Vouillon"
+  "Jérémie Dimino"
+]
+maintainer: [
+  "Anton Bachin <antonbachin@yahoo.com>"
+]
+dev-repo: "git+https://github.com/ocsigen/lwt.git"
+
+depends: [
+  "cppo" {build & >= "1.1.0"}
+  "dune" {>= "1.7.0"}
+  "mmap" {>= "1.1.0"} # mmap is needed as long as Lwt supports OCaml < 4.06.0.
+  "ocaml" {>= "4.02.0"}
+  "ocplib-endian"
+  "result" # result is needed as long as Lwt supports OCaml 4.02.
+  "seq" # seq is needed as long as Lwt supports OCaml < 4.07.0.
+
+  "bisect_ppx" {dev & >= "1.3.0"}
+  "ocamlfind" {dev & >= "1.7.3-1"}
+]
+
+depopts: [
+  "base-threads"
+  "base-unix"
+  "conf-libev"
+]
+
+conflicts: [
+  "ocaml-variants" {= "4.02.1+BER"}
+]
+
+post-messages: [
+  "Lwt 5.0.0 will make some breaking changes in November 2019. See
+  https://github.com/ocsigen/lwt/issues/584"
+]
+
+build: [
+  ["dune" "build" "-p" name "-j" jobs]
+]
+
+description: "A promise is a value that may become determined in the future.
+
+Lwt provides typed, composable promises. Promises that are resolved by I/O are
+resolved by Lwt in parallel.
+
+Meanwhile, OCaml code, including code creating and waiting on promises, runs in
+a single thread by default. This reduces the need for locks or other
+synchronization primitives. Code can be run in parallel on an opt-in basis."
+
+url {
+  src: "https://github.com/ocsigen/lwt/archive/4.3.0.tar.gz"
+  checksum: "md5=1a72b5ae4245707c12656632a25fc18c"
+}
diff --git a/packages/lwt_ppx/lwt_ppx.1.2.3/opam b/packages/lwt_ppx/lwt_ppx.1.2.3/opam
new file mode 100644
index 00000000000..73f9b2c2a0a
--- /dev/null
+++ b/packages/lwt_ppx/lwt_ppx.1.2.3/opam
@@ -0,0 +1,34 @@
+opam-version: "2.0"
+
+synopsis: "PPX syntax for Lwt, providing something similar to async/await from JavaScript"
+
+version: "1.2.3"
+license: "MIT"
+homepage: "https://github.com/ocsigen/lwt"
+doc: "https://ocsigen.org/lwt/api/Ppx_lwt"
+bug-reports: "https://github.com/ocsigen/lwt/issues"
+
+authors: [
+  "Gabriel Radanne"
+]
+maintainer: [
+  "Anton Bachin <antonbachin@yahoo.com>"
+]
+dev-repo: "git+https://github.com/ocsigen/lwt.git"
+
+depends: [
+  "dune"
+  "lwt"
+  "ocaml" {>= "4.02.0"}
+  "ocaml-migrate-parsetree" {>= "1.3.0"}
+  "ppx_tools_versioned" {>= "5.2.3"}
+]
+
+build: [
+  ["dune" "build" "-p" name "-j" jobs]
+]
+
+url {
+  src: "https://github.com/ocsigen/lwt/archive/4.3.0.tar.gz"
+  checksum: "md5=1a72b5ae4245707c12656632a25fc18c"
+}
diff --git a/packages/lwt_react/lwt_react.1.1.3/opam b/packages/lwt_react/lwt_react.1.1.3/opam
new file mode 100644
index 00000000000..a2636879ef2
--- /dev/null
+++ b/packages/lwt_react/lwt_react.1.1.3/opam
@@ -0,0 +1,33 @@
+opam-version: "2.0"
+
+synopsis: "Helpers for using React with Lwt"
+
+version: "1.1.3"
+license: "MIT"
+homepage: "https://github.com/ocsigen/lwt"
+doc: "https://ocsigen.org/lwt/api/Lwt_react"
+bug-reports: "https://github.com/ocsigen/lwt/issues"
+
+authors: [
+  "Jérémie Dimino"
+]
+maintainer: [
+  "Anton Bachin <antonbachin@yahoo.com>"
+]
+dev-repo: "git+https://github.com/ocsigen/lwt.git"
+
+depends: [
+  "dune"
+  "lwt" {>= "3.0.0"}
+  "ocaml"
+  "react" {>= "1.0.0"}
+]
+
+build: [
+  ["dune" "build" "-p" name "-j" jobs]
+]
+
+url {
+  src: "https://github.com/ocsigen/lwt/archive/4.3.0.tar.gz"
+  checksum: "md5=1a72b5ae4245707c12656632a25fc18c"
+}
diff --git a/packages/ocurl/ocurl.0.7.10/opam b/packages/ocurl/ocurl.0.7.10/opam
index 72f49f4400d..1e4d7710a16 100644
--- a/packages/ocurl/ocurl.0.7.10/opam
+++ b/packages/ocurl/ocurl.0.7.10/opam
@@ -20,9 +20,13 @@ depends: [
   "ocaml"
   "ocamlfind" {build}
   "base-unix"
+  "base-unsafe-string"
   "conf-libcurl"
 ]
 depopts: ["lwt"]
+conflicts: [
+  "lwt" {>= "4.0.0"}
+]
 synopsis: "Bindings to libcurl"
 description: """
 Client-side URL transfer library, supporting HTTP and a multitude of
diff --git a/packages/ocurl/ocurl.0.8.0/opam b/packages/ocurl/ocurl.0.8.0/opam
index 451b15a1127..8ed64bc6b94 100644
--- a/packages/ocurl/ocurl.0.8.0/opam
+++ b/packages/ocurl/ocurl.0.8.0/opam
@@ -24,6 +24,9 @@ depends: [
   "conf-libcurl"
 ]
 depopts: ["lwt"]
+conflicts: [
+  "lwt" {>= "4.0.0"}
+]
 synopsis: "Bindings to libcurl"
 description: """
 Client-side URL transfer library, supporting HTTP and a multitude of