diff --git a/aws-s3-eio.opam b/aws-s3-eio.opam
new file mode 100644
index 0000000..ab4ff20
--- /dev/null
+++ b/aws-s3-eio.opam
@@ -0,0 +1,32 @@
+opam-version: "2.0"
+maintainer: "Anders Fugmann <anders@fugmann.net>"
+authors: "Anders Fugmann"
+license: "BSD-3-Clause"
+homepage: "https://github.com/andersfugmann/aws-s3"
+dev-repo: "git+https://github.com/andersfugmann/aws-s3"
+bug-reports: "https://github.com/andersfugmann/aws-s3/issues"
+doc: "https://andersfugmann.github.io/aws-s3/"
+build: [
+  ["dune" "subst"] {dev}
+  ["dune" "build" "-p" name "-j" jobs]
+]
+depends: [
+  "ocaml" {>= "4.14.0"}
+  "dune" {>= "2.0.0"}
+  "aws-s3" {= version}
+  "cohttp-eio"
+  "eio" {>= "1.2" }
+]
+synopsis: "Ocaml library for accessing Amazon S3 - Eio version"
+description: """
+This library provides access to Amazon Simple Storage Solution (S3).
+The library supports:
+* Copying file to and from s3
+* List files in S3 (from root)
+* Delete single/multi object in S3
+* HEAD operation on single objects
+* Streaming transfer to and from aws.
+* Multi part upload (including s3 -> s3 copy)
+* Fetching machine role/credentials (though IAM)
+
+This library uses eio for concurrency"""
diff --git a/aws-s3-eio/.#io.ml b/aws-s3-eio/.#io.ml
new file mode 120000
index 0000000..529b732
--- /dev/null
+++ b/aws-s3-eio/.#io.ml
@@ -0,0 +1 @@
+afu@slartibartfast.1073069:1729245178
\ No newline at end of file
diff --git a/aws-s3-eio/bin/aws_cli_async.ml b/aws-s3-eio/bin/aws_cli_async.ml
new file mode 100644
index 0000000..cb852f3
--- /dev/null
+++ b/aws-s3-eio/bin/aws_cli_async.ml
@@ -0,0 +1,7 @@
+module Aws = Aws_cli.Aws.Make(Aws_s3_async.Io)
+
+let exec cmd =
+  Async.Thread_safe.block_on_async_exn (fun () -> Aws.exec cmd)
+
+let () =
+  Aws_cli.Cli.parse exec
diff --git a/aws-s3-eio/bin/dune b/aws-s3-eio/bin/dune
new file mode 100644
index 0000000..69b37f8
--- /dev/null
+++ b/aws-s3-eio/bin/dune
@@ -0,0 +1,6 @@
+(executable
+ (name        aws_cli_eio)
+ (public_name aws-cli-eio)
+ (libraries aws_cli aws-s3-eio)
+ (package aws-s3-eio)
+)
diff --git a/aws-s3-eio/credentials.ml b/aws-s3-eio/credentials.ml
new file mode 100644
index 0000000..8be1fe3
--- /dev/null
+++ b/aws-s3-eio/credentials.ml
@@ -0,0 +1,6 @@
+(** Async aware Credentials.
+    For API documentation
+    @see <../../../aws-s3/Aws_s3/Credentials/Make/index.html>({!module:Aws_s3.Credentials.Make})
+*)
+include Aws_s3.Credentials.Make(Io)
+type t = Aws_s3.Credentials.t
diff --git a/aws-s3-eio/dune b/aws-s3-eio/dune
new file mode 100644
index 0000000..daafbbd
--- /dev/null
+++ b/aws-s3-eio/dune
@@ -0,0 +1,6 @@
+(library
+ (name aws_s3_eio)
+  (public_name aws-s3-eio)
+  (synopsis  "Eio backed for aws-s3")
+  (libraries aws-s3 eio ipaddr.unix cohttp-eio)
+)
diff --git a/aws-s3-eio/io.ml b/aws-s3-eio/io.ml
new file mode 100644
index 0000000..e7c7208
--- /dev/null
+++ b/aws-s3-eio/io.ml
@@ -0,0 +1,113 @@
+module Deferred = struct
+  type 'a t = 'a
+  module Or_error = struct
+    type nonrec 'a t = ('a, exn) result t
+    let return v = Ok v
+    let fail exn = Error exn
+    let catch f =
+      match f () with
+      | v -> v
+      | exception exn -> Error exn
+
+    let (>>=) : 'a t -> ('a -> 'b t) -> 'b t = fun v f ->
+      match v with
+      | Ok v -> f v
+      | err -> err
+  end
+
+  let (>>=) v f = f v
+  let (>>|) v f = f v
+  let (>>=?) v f =
+    match v with
+    | Ok v -> f v
+    | err -> err
+
+  let return v = v
+  let after delay =
+    (* Need some Eio function to delay:
+       Eio.Time.Sleep time_state (float delay)
+    *)
+    failwith "Not implemented"
+  let catch f = match f () with
+    | v -> Ok v
+    | exception exn -> Error exn
+
+  (* Need some state to be able to spawn a new fiber *)
+  let async = (* Eio spawn a new fiber *) failwith "Not implemented"
+end
+
+module Ivar = struct
+  type 'a t = ('a Eio.Promise.t * 'a Eio.Promise.u)
+  let create () = Eio.Promise.create ()
+  let fill (_t, u) v = Eio.Promise.resolve u v
+  let wait (t, _u) = Eio.Promise.await t
+end
+
+module Pipe = struct
+  (* Create an infinite pipe that can be closed.
+     Then the reader is closed any new writes will fail
+     When the writer is closed the read can read new message until last element is read
+     The pipe uses callbacks????
+  *)
+
+  type ('a, 'b) pipe = ('a, 'b) Pipe.pipe
+  type 'a writer = 'a Pipe.Writer.t
+  type 'a reader = 'a Pipe.Reader.t
+
+  let flush writer = Pipe.downstream_flushed writer >>= fun _ -> return ()
+  let read reader = Pipe.read reader >>= function
+    | `Eof -> return None
+    | `Ok v -> return (Some v)
+  let write writer data =
+    (* Pipe.write writer data *)
+    Pipe.write_without_pushback writer data;
+    return ()
+  let close writer = Pipe.close writer
+  let close_reader reader = Pipe.close_read reader
+  let create_reader ~f = Pipe.create_reader ~close_on_exception:true f
+  let create_writer ~f = Pipe.create_writer f
+  let transfer reader writer = Pipe.transfer_id reader writer
+  let create () = Pipe.create ()
+  let is_closed pipe = Pipe.is_closed pipe
+  let closed pipe = Pipe.closed pipe
+end
+
+module Net = struct
+  let connect ?connect_timeout_ms ~inet ~host ~port ~scheme () =
+    let uri =
+      let scheme = match scheme with
+        | `Http -> "http"
+        | `Https -> "https"
+      in
+      Uri.make ~scheme ~host:host ~port ()
+    in
+    let options =
+      let domain : Async_unix.Unix.socket_domain =
+        match inet with
+          | `V4 -> PF_INET
+          | `V6 -> PF_INET6
+      in
+      Core_unix.[AI_FAMILY domain]
+    in
+    let close_socket_no_error = function
+      | Conduit_async.V3.Inet_sock socket -> try Socket.shutdown socket `Both; with _ -> ()
+    in
+    let interrupt = match connect_timeout_ms with
+      | None -> None
+      | Some ms -> Some (Async.after (Time_float_unix.Span.of_int_ms ms))
+    in
+    Async.try_with (fun () -> Conduit_async.V3.connect_uri ?interrupt ~options uri) >>=? fun (socket, ic, oc) ->
+    let reader = Reader.pipe ic in
+    don't_wait_for (
+      Async_kernel.Pipe.closed reader >>= fun () ->
+      Monitor.try_with ~name:"Io.Net.connect connection-cleanup" (fun () ->
+        Writer.close oc >>= fun () ->
+        Reader.close ic >>= fun () ->
+        return ()
+      ) >>= fun _ ->
+      close_socket_no_error socket;
+      return ()
+    );
+    let writer = Writer.pipe oc in
+    Deferred.Or_error.return (reader, writer)
+end
diff --git a/aws-s3-eio/io.mli b/aws-s3-eio/io.mli
new file mode 100644
index 0000000..bf76ce8
--- /dev/null
+++ b/aws-s3-eio/io.mli
@@ -0,0 +1,2 @@
+include Aws_s3.Types.Io
+  with type 'a Deferred.t = 'a
diff --git a/aws-s3-eio/s3.ml b/aws-s3-eio/s3.ml
new file mode 100644
index 0000000..bf424b5
--- /dev/null
+++ b/aws-s3-eio/s3.ml
@@ -0,0 +1,5 @@
+(** Async aware S3 commands.
+    For API documentation
+    @see <../../../aws-s3/Aws_s3/S3/Make/index.html>({!module:Aws_s3.S3.Make})
+*)
+include Aws_s3.S3.Make(Io)