diff --git a/.gitmodules b/.gitmodules
index a8f29950..82ceaa66 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -68,3 +68,6 @@
 [submodule "fmt"]
 	path = fmt
 	url = https://github.com/fmtlib/fmt.git
+[submodule "nlohmann_json"]
+	path = nlohmann_json
+	url = https://github.com/nlohmann/json.git
diff --git a/README.md b/README.md
index 59eaa9a8..7892c849 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,7 @@ both can be installed with `sdkmanager` command line tool.
 * `python`: build dep of `opencc`
 * `opencc`: for `opencc_dict`
 * `gperf`: build dep of `libiconv`
+* `rustup`: build dep of `libchewing`
 
 ## Libraries
 
@@ -40,6 +41,7 @@ both can be installed with `sdkmanager` command line tool.
 * yaml-cpp: [jbeder/yaml-cpp](https://github.com/jbeder/yaml-cpp)
 * leveldb: [google/leveldb](https://github.com/google/leveldb)
 * marisa-trie: [s-yata/marisa-trie](https://github.com/s-yata/marisa-trie)
+* nlohmann_json: [nlohmann/json](https://github.com/nlohmann/json)
 * librime: [rime/librime](https://github.com/rime/librime)
 * librime-lua: [rime/librime-lua](https://github.com/hchunhui/librime-lua)
 * librime-octagram: [rime/librime-octagram](https://github.com/lotem/librime-octagram)
diff --git a/nlohmann_json b/nlohmann_json
new file mode 160000
index 00000000..55f93686
--- /dev/null
+++ b/nlohmann_json
@@ -0,0 +1 @@
+Subproject commit 55f93686c01528224f448c19128836e7df245f72
diff --git a/src/Main.hs b/src/Main.hs
index 57f5db64..5d3440a2 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -29,6 +29,7 @@ import Rules.LibThai
 import Rules.LibUV
 import Rules.Lua
 import Rules.Marisa
+import Rules.NlohmannJSON
 import Rules.OpenCC
 import Rules.RustToolchain
 import Rules.YAMLCpp
@@ -68,6 +69,7 @@ main = do
       marisaSourceRule
       hostMarisaRule
       marisaRule
+      nlohmannJSONRule
       librimeRule
       libhangulRule
       libchewingRule
@@ -94,6 +96,7 @@ main = do
                 "yaml-cpp",
                 "leveldb",
                 "marisa",
+                "nlohmann_json",
                 "librime",
                 "libhangul",
                 "chewing-dict",
diff --git a/src/Rules/NlohmannJSON.hs b/src/Rules/NlohmannJSON.hs
new file mode 100644
index 00000000..723e5afe
--- /dev/null
+++ b/src/Rules/NlohmannJSON.hs
@@ -0,0 +1,36 @@
+{-# LANGUAGE DeriveAnyClass #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE TypeFamilies #-}
+
+module Rules.NlohmannJSON (nlohmannJSONRule) where
+
+import Base
+import CMakeBuilder
+
+data NlohmannJSON = NlohmannJSON
+  deriving stock (Eq, Show, Typeable, Generic)
+  deriving anyclass (Hashable, Binary, NFData)
+
+type instance RuleResult NlohmannJSON = ()
+
+nlohmannJSONRule :: Rules ()
+nlohmannJSONRule = do
+  buildNlohmannJSON <-
+    useCMake
+      (cmakeBuilder "nlohmann_json")
+        { cmakeFlags =
+            const
+              [ "-DBUILD_TESTING=OFF",
+                "-DJSON_BuildTests=OFF",
+                -- install boost headers to parent directory, symlink it afterwards
+                "-DCMAKE_INSTALL_INCLUDEDIR=" <> "../include"
+              ],
+          -- symlink headers for each abi to reduce size
+          postBuildEachABI = BuildActionABI $ \_ env ->
+            liftIO $ do
+              let includePath = buildEnvOutPrefix env </> "include"
+              whenM (doesPathExist includePath) $ removePathForcibly includePath
+              createDirectoryLink (".." </> "include") includePath
+        }
+  "nlohmann_json" ~> buildWithAndroidEnv buildNlohmannJSON NlohmannJSON