diff --git a/gnu/packages/web.scm b/gnu/packages/web.scm
index 8e22997957..82923786f2 100644
--- a/gnu/packages/web.scm
+++ b/gnu/packages/web.scm
@@ -95,6 +95,7 @@ (define-module (gnu packages web)
   #:use-module (guix build-system cargo)
   #:use-module (guix build-system cmake)
   #:use-module (guix build-system copy)
+  #:use-module (guix build-system dune)
   #:use-module (guix build-system glib-or-gtk)
   #:use-module (guix build-system gnu)
   #:use-module (guix build-system go)
@@ -172,6 +173,7 @@ (define-module (gnu packages web)
   #:use-module (gnu packages node)
   #:use-module (gnu packages node-xyz)
   #:use-module (gnu packages nss)
+  #:use-module (gnu packages ocaml)
   #:use-module (gnu packages openldap)
   #:use-module (gnu packages openstack)
   #:use-module (gnu packages package-management)
@@ -1937,6 +1939,99 @@ (define-public esbuild
 and other data, for distribution on the web.")
     (license license:expat)))
 
+(define-public ocaml-flow-parser
+  (package
+    (name "ocaml-flow-parser")
+    (version "0.159.0")
+    (outputs '("out" "js"))
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/facebook/flow")
+             (commit (string-append "v" version))))
+       (sha256
+        (base32 "1i9svf641s24nj4w6y9vvglzg29h0lr4n9a6mvwrn9psy9x1lril"))
+       (file-name (git-file-name "flow" version))))
+    (build-system dune-build-system)
+    (propagated-inputs (list ocaml-base
+                             ocaml-core-kernel
+                             ocaml-dtoa
+                             ocaml-sedlex
+                             ocaml-wtf8))
+    (native-inputs (list js-of-ocaml
+                         ocamlbuild
+                         ocaml-findlib
+                         ocaml-ounit2
+                         ocaml-ppx-deriving
+                         ocaml-ppx-gen-rec
+                         ocaml-visitors))
+    (arguments
+     (list
+      #:tests? #f ; tests need lwt_ppx
+      #:package "flow_parser"
+      #:phases
+      #~(modify-phases %standard-phases
+          (add-before 'build 'chdir
+            (lambda args
+              (chdir "src/parser")))
+          (add-before 'build 'patch-source
+            (lambda args
+              ;; Avoid errors with newer OCaml:
+              ;; "Error (warning 16 [unerasable-optional-argument]):"
+              ;;   " this optional argument cannot be erased."
+              ;; "Error (warning 69 [unused-field]):"
+              ;;   " mutable record field buf is never mutated."
+              ;; "Error (warning 70 [missing-mli]): Cannot find interface file."
+              (substitute* "_tags"
+                (("<\\*\\.ml\\*>: warn[(]-39[)]")
+                 "<*.ml*>: warn(-16-39-70)"))
+              (substitute* "../../_tags"
+                (("<\\*\\*/\\*.ml\\*>: ")
+                 "<**/*.ml*>: warn(-69), "))
+              ;; Deprecation of Js.Unsafe.variable, Js.Error, Js.raise_js_error
+              (substitute* "flow_parser_js.ml"
+                (("Js\\.Unsafe\\.variable")
+                 "Js.Unsafe.pure_js_expr"))
+              (substitute* "flow_parser_dot_js.ml"
+                (("Js\\.Error")
+                 "Js_of_ocaml.Js_error.Exn")
+                (("Js\\.raise_js_error")
+                 "Js_of_ocaml.Js_error.raise_"))))
+          (replace 'build
+            (lambda args
+              (invoke "make"
+                      (string-append "CC=" #$(cc-for-target))
+                      "build-parser")))
+          (add-after 'build 'build-js
+            (lambda args
+              (invoke "make"
+                      (string-append "CC=" #$(cc-for-target))
+                      "js")))
+          (replace 'check
+            (lambda* (#:key tests? #:allow-other-keys)
+              (when tests?
+                (invoke "make"
+                        (string-append "CC=" #$(cc-for-target))
+                        "test-ocaml"))))
+          (replace 'install
+            (lambda args
+              (invoke "make"
+                      (string-append "CC=" #$(cc-for-target))
+                      "ocamlfind-install")))
+          (add-after 'install 'install-js
+            (lambda args
+              (install-file "flow_parser.js"
+                            (string-append #$output:js
+                                           "/share/javascript/flow")))))))
+    (properties `((upstream-name . "flow_parser")))
+    (home-page "https://flow.org")
+    (synopsis "Parser for the Flow JavaScript type system")
+    (description "Flow is a gradual type system for JavaScript.  This package
+provides the Flow parser, which is an OCaml library that can also be compiled
+to JavaScript.")
+    (license license:expat)))
+
 (define-public tinyproxy
   (package
     (name "tinyproxy")
