diff --git a/page/Fcitx5.d.ts b/page/Fcitx5.d.ts
index 79863d1..fe5d91d 100644
--- a/page/Fcitx5.d.ts
+++ b/page/Fcitx5.d.ts
@@ -8,6 +8,8 @@ export interface FCITX {
   getAllInputMethods: () => { name: string, displayName: string, languageCode: string }[]
   setStatusAreaCallback: (callback: () => void) => void
   updateStatusArea: () => void
+  getConfig: (uri: string) => string
+  setConfig: (uri: string, json: object) => void
 }
 
 export const fcitxReady: Promise<null>
diff --git a/page/config.ts b/page/config.ts
new file mode 100644
index 0000000..0c4332e
--- /dev/null
+++ b/page/config.ts
@@ -0,0 +1,9 @@
+import Module from './module'
+
+export function getConfig(uri: string) {
+  return Module.ccall('get_config', 'string', ['string'], [uri])
+}
+
+export function setConfig(uri: string, json: object) {
+  return Module.ccall('set_config', 'void', ['string', 'string'], [uri, JSON.stringify(json)])
+}
diff --git a/page/index.ts b/page/index.ts
index 8abadaa..fa15d80 100644
--- a/page/index.ts
+++ b/page/index.ts
@@ -3,6 +3,7 @@ import { blur, clickPanel, focus } from './focus'
 import { keyEvent } from './keycode'
 import { commit, hidePanel, placePanel, setPreedit } from './client'
 import { currentInputMethod, getAllInputMethods, getInputMethods, setCurrentInputMethod, setInputMethods } from './input-method'
+import { getConfig, setConfig } from './config'
 
 let res: (value: any) => void
 
@@ -40,6 +41,8 @@ window.fcitx = {
   getInputMethods,
   setInputMethods,
   getAllInputMethods,
+  getConfig,
+  setConfig,
   enable() {
     document.addEventListener('focus', focus, true)
     document.addEventListener('blur', blur, true)
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 6568ed1..a745851 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -2,6 +2,7 @@ add_executable(Fcitx5
     fcitx.cpp
     keycode.cpp
     input_method.cpp
+    config.cpp
 )
 
 target_include_directories(Fcitx5 PRIVATE
diff --git a/src/config.cpp b/src/config.cpp
new file mode 100644
index 0000000..2ebd0d3
--- /dev/null
+++ b/src/config.cpp
@@ -0,0 +1,267 @@
+#include <emscripten.h>
+#include <fcitx-config/configuration.h>
+#include <fcitx-config/rawconfig.h>
+#include <fcitx-utils/stringutils.h>
+#include <fcitx/addonmanager.h>
+#include <fcitx/inputmethodengine.h>
+#include <fcitx/inputmethodentry.h>
+#include <fcitx/inputmethodmanager.h>
+#include <fcitx/instance.h>
+#include <nlohmann/json.hpp>
+#include <string>
+
+namespace fcitx {
+extern std::unique_ptr<Instance> instance;
+
+constexpr char globalConfigPath[] = "fcitx://config/global";
+constexpr char addonConfigPrefix[] = "fcitx://config/addon/";
+constexpr char imConfigPrefix[] = "fcitx://config/inputmethod/";
+
+/// Convert configuration into a json object.
+nlohmann::json configToJson(const Configuration &config);
+
+nlohmann::json configValueToJson(const Configuration &config);
+
+using namespace std::literals::string_literals;
+
+static nlohmann::json &jsonLocate(nlohmann::json &j, const std::string &group,
+                                  const std::string &option);
+static nlohmann::json configValueToJson(const RawConfig &config);
+static nlohmann::json configSpecToJson(const RawConfig &config);
+static nlohmann::json configSpecToJson(const Configuration &config);
+static void mergeSpecAndValue(nlohmann::json &specJson,
+                              const nlohmann::json &valueJson);
+static RawConfig jsonToRawConfig(const nlohmann::json &);
+static std::tuple<std::string, std::string>
+parseAddonUri(const std::string &uri);
+
+nlohmann::json getConfig(const std::string &uri) {
+    FCITX_DEBUG() << "getConfig " << uri;
+    if (uri == globalConfigPath) {
+        auto &config = instance->globalConfig().config();
+        return configToJson(config);
+    } else if (stringutils::startsWith(uri, addonConfigPrefix)) {
+        auto [addonName, subPath] = parseAddonUri(uri);
+        auto *addonInfo = instance->addonManager().addonInfo(addonName);
+        if (!addonInfo) {
+            return {{"ERROR", "Addon \""s + addonName + "\" does not exist"}};
+        } else if (!addonInfo->isConfigurable()) {
+            return {
+                {"ERROR", "Addon \""s + addonName + "\" is not configurable"}};
+        }
+        auto *addon = instance->addonManager().addon(addonName, true);
+        if (!addon) {
+            return {{"ERROR",
+                     "Failed to get config for addon \""s + addonName + "\""}};
+        }
+        auto *config =
+            subPath.empty() ? addon->getConfig() : addon->getSubConfig(subPath);
+        if (!config) {
+            return {{"ERROR",
+                     "Failed to get config for addon \""s + addonName + "\""}};
+        }
+        return configToJson(*config);
+    } else if (stringutils::startsWith(uri, imConfigPrefix)) {
+        auto imName = uri.substr(sizeof(imConfigPrefix) - 1);
+        auto *entry = instance->inputMethodManager().entry(imName);
+        if (!entry) {
+            return {
+                {"ERROR", "Input method \""s + imName + "\" doesn't exist"}};
+        }
+        if (!entry->isConfigurable()) {
+            return {{"ERROR",
+                     "Input method \""s + imName + "\" is not configurable"}};
+        }
+        auto *engine = instance->inputMethodEngine(imName);
+        if (!engine) {
+            return {{"ERROR", "Failed to get engine for input method \""s +
+                                  imName + "\""}};
+        }
+        auto *config = engine->getConfigForInputMethod(*entry);
+        if (!config) {
+            return {{"ERROR", "Failed to get config for input method \""s +
+                                  imName + "\""}};
+        }
+        return configToJson(*config);
+    } else {
+        return {{"ERROR", "Bad config URI \""s + uri + "\""}};
+    }
+}
+
+extern "C" {
+EMSCRIPTEN_KEEPALIVE const char *get_config(const char *uri) {
+    static std::string ret;
+    ret = getConfig(std::string(uri)).dump();
+    return ret.c_str();
+}
+
+EMSCRIPTEN_KEEPALIVE bool set_config(const char *uri_, const char *json_) {
+    FCITX_DEBUG() << "setConfig " << uri_;
+    auto config = jsonToRawConfig(nlohmann::json::parse(json_));
+    auto uri = std::string(uri_);
+    if (uri == globalConfigPath) {
+        auto &gc = instance->globalConfig();
+        gc.load(config, true);
+        if (gc.safeSave()) {
+            instance->reloadConfig();
+            return true;
+        } else {
+            return false;
+        }
+    } else if (stringutils::startsWith(uri, addonConfigPrefix)) {
+        auto [addonName, subPath] = parseAddonUri(uri);
+        auto *addon = instance->addonManager().addon(addonName, true);
+        if (addon) {
+            FCITX_DEBUG() << "Saving addon config to: " << uri;
+            if (subPath.empty()) {
+                addon->setConfig(config);
+            } else {
+                addon->setSubConfig(subPath, config);
+            }
+            return true;
+        } else {
+            FCITX_ERROR() << "Failed to get addon";
+            return false;
+        }
+    } else if (stringutils::startsWith(uri, imConfigPrefix)) {
+        auto im = uri.substr(sizeof(imConfigPrefix) - 1);
+        const auto *entry = instance->inputMethodManager().entry(im);
+        auto *engine = instance->inputMethodEngine(im);
+        if (entry && engine) {
+            FCITX_DEBUG() << "Saving input method config to: " << uri;
+            engine->setConfigForInputMethod(*entry, config);
+            return true;
+        } else {
+            FCITX_ERROR() << "Failed to get input method";
+            return false;
+        }
+    } else {
+        return false;
+    }
+}
+}
+
+void jsonFillRawConfigValues(const nlohmann::json &j, RawConfig &config) {
+    if (j.is_string()) {
+        config = j.get<std::string>();
+        return;
+    }
+    if (j.is_object()) {
+        for (const auto [key, subJson] : j.items()) {
+            auto subConfig = config.get(key, true);
+            jsonFillRawConfigValues(subJson, *subConfig);
+        }
+        return;
+    }
+    FCITX_FATAL() << "Unknown value json: " << j.dump();
+}
+
+RawConfig jsonToRawConfig(const nlohmann::json &j) {
+    RawConfig config;
+    jsonFillRawConfigValues(j, config);
+    return config;
+}
+
+nlohmann::json &jsonLocate(nlohmann::json &j, const std::string &groupPath,
+                           const std::string &option) {
+    auto paths = stringutils::split(groupPath, "$");
+    paths.pop_back(); // remove type
+    paths.push_back(option);
+    nlohmann::json *cur = &j;
+    for (const auto &part : paths) {
+        auto &children =
+            *cur->emplace("Children", nlohmann::json::array()).first;
+        bool exist = false;
+        for (auto &child : children) {
+            if (child["Option"] == part) {
+                exist = true;
+                cur = &child;
+                break;
+            }
+        }
+        if (!exist) {
+            cur = &children.emplace_back(nlohmann::json::object());
+        }
+    }
+    return *cur;
+}
+
+nlohmann::json configValueToJson(const RawConfig &config) {
+    if (!config.hasSubItems()) {
+        return nlohmann::json(config.value());
+    }
+    nlohmann::json j;
+    for (auto &subItem : config.subItems()) {
+        auto subConfig = config.get(subItem);
+        j[subItem] = configValueToJson(*subConfig);
+    }
+    return j;
+}
+
+nlohmann::json configValueToJson(const Configuration &config) {
+    RawConfig raw;
+    config.save(raw);
+    return configValueToJson(raw);
+}
+
+nlohmann::json configSpecToJson(const RawConfig &config) {
+    // first level  -> Path1$Path2$...$Path_n$ConfigType
+    // second level -> OptionName
+    nlohmann::json spec;
+    auto groups = config.subItems();
+    for (const auto &group : groups) {
+        auto groupConfig = config.get(group);
+        auto options = groupConfig->subItems();
+        for (const auto &option : options) {
+            auto optionConfig = groupConfig->get(option);
+            nlohmann::json &optSpec = jsonLocate(spec, group, option);
+            optSpec["Option"] = option;
+            optionConfig->visitSubItems(
+                [&](const RawConfig &config, const std::string &path) {
+                    optSpec[path] = configValueToJson(config);
+                    return true;
+                });
+        }
+    }
+    return spec;
+}
+
+void mergeSpecAndValue(nlohmann::json &specJson,
+                       const nlohmann::json &valueJson) {
+    if (specJson.find("Type") != specJson.end()) {
+        specJson["Value"] = valueJson;
+    }
+    for (auto &child : specJson["Children"]) {
+        const auto iter = valueJson.find(child["Option"]);
+        if (iter != valueJson.end()) {
+            mergeSpecAndValue(child, *iter);
+        }
+    }
+}
+
+nlohmann::json configSpecToJson(const Configuration &config) {
+    RawConfig rawDesc;
+    config.dumpDescription(rawDesc);
+    return configSpecToJson(rawDesc);
+}
+
+nlohmann::json configToJson(const Configuration &config) {
+    // specJson contains config definitions
+    auto specJson = configSpecToJson(config);
+    // valueJson contains actual values that user could change
+    auto valueJson = configValueToJson(config);
+    mergeSpecAndValue(specJson, valueJson);
+    return specJson;
+}
+
+static std::tuple<std::string, std::string>
+parseAddonUri(const std::string &uri) {
+    auto addon = uri.substr(sizeof(addonConfigPrefix) - 1);
+    auto pos = addon.find('/');
+    if (pos == std::string::npos) {
+        return {addon, ""};
+    } else {
+        return {addon.substr(0, pos), addon.substr(pos + 1)};
+    }
+}
+} // namespace fcitx