diff --git a/plugins/plugins_module.cc b/plugins/plugins_module.cc
index 86aaa1b03..af78c2bf8 100644
--- a/plugins/plugins_module.cc
+++ b/plugins/plugins_module.cc
@@ -3,6 +3,7 @@
 // Distributed under the BSD License
 //
 
+#include <algorithm>
 #include <boost/algorithm/string.hpp>
 #include <boost/dll.hpp>
 #include <filesystem>
@@ -78,7 +79,7 @@ string PluginManager::plugin_name_of(fs::path plugin_file) {
   }
   // replace dash with underscore, for the plugin name is part of the module
   // initializer function name.
-  boost::replace_all(name, "-", "_");
+  std::replace(name.begin(), name.end(), '-', '_');
   return name;
 }
 
diff --git a/src/rime/algo/utilities.cc b/src/rime/algo/utilities.cc
index 8000eb1bf..5b032c18a 100644
--- a/src/rime/algo/utilities.cc
+++ b/src/rime/algo/utilities.cc
@@ -6,35 +6,25 @@
 //
 #include <fstream>
 #include <sstream>
-#include <boost/algorithm/string.hpp>
 #include <rime/algo/utilities.h>
 
 namespace rime {
 
 int CompareVersionString(const string& x, const string& y) {
-  if (x.empty() && y.empty())
-    return 0;
-  if (x.empty())
-    return -1;
-  if (y.empty())
-    return 1;
-  vector<string> xx, yy;
-  boost::split(xx, x, boost::is_any_of("."));
-  boost::split(yy, y, boost::is_any_of("."));
-  size_t i = 0;
-  for (; i < xx.size() && i < yy.size(); ++i) {
-    int dx = atoi(xx[i].c_str());
-    int dy = atoi(yy[i].c_str());
-    if (dx != dy)
-      return dx - dy;
-    int c = xx[i].compare(yy[i]);
-    if (c != 0)
-      return c;
+  size_t i = 0, j = 0, m = x.size(), n = y.size();
+  while (i < m || j < n) {
+    int v1 = 0, v2 = 0;
+    while (i < m && x[i] != '.')
+      v1 = v1 * 10 + (int)(x[i++] - '0');
+    ++i;
+    while (j < n && y[j] != '.')
+      v2 = v2 * 10 + (int)(y[j++] - '0');
+    ++j;
+    if (v1 > v2)
+      return 1;
+    if (v1 < v2)
+      return -1;
   }
-  if (i < xx.size())
-    return 1;
-  if (i < yy.size())
-    return -1;
   return 0;
 }
 
diff --git a/src/rime/config/config_data.cc b/src/rime/config/config_data.cc
index 995b76e31..7258a460e 100644
--- a/src/rime/config/config_data.cc
+++ b/src/rime/config/config_data.cc
@@ -5,9 +5,9 @@
 #include <cctype>
 #include <cstdlib>
 #include <fstream>
+#include <sstream>
 #include <boost/algorithm/string.hpp>
 #include <filesystem>
-#include <boost/format.hpp>
 #include <yaml-cpp/yaml.h>
 #include <rime/config/config_compiler.h>
 #include <rime/config/config_cow_ref.h>
@@ -96,7 +96,9 @@ bool ConfigData::IsListItemReference(const string& key) {
 }
 
 string ConfigData::FormatListIndex(size_t index) {
-  return boost::str(boost::format("@%u") % index);
+  std::ostringstream formatted;
+  formatted << "@" << index;
+  return formatted.str();
 }
 
 static const string kAfter("after");
@@ -286,9 +288,9 @@ an<ConfigItem> ConvertFromYaml(const YAML::Node& node,
 void EmitScalar(const string& str_value, YAML::Emitter* emitter) {
   if (str_value.find_first_of("\r\n") != string::npos) {
     *emitter << YAML::Literal;
-  } else if (!boost::algorithm::all(str_value,
-                                    boost::algorithm::is_alnum() ||
-                                        boost::algorithm::is_any_of("_."))) {
+  } else if (!std::all_of(str_value.cbegin(), str_value.cend(), [](auto ch) {
+               return std::isalnum(ch) || ch == '_' || ch == '.';
+             })) {
     *emitter << YAML::DoubleQuoted;
   }
   *emitter << str_value;
diff --git a/src/rime/dict/mapped_file.h b/src/rime/dict/mapped_file.h
index 03352f031..9257968c9 100644
--- a/src/rime/dict/mapped_file.h
+++ b/src/rime/dict/mapped_file.h
@@ -9,7 +9,6 @@
 
 #include <stdint.h>
 #include <cstring>
-#include <boost/utility.hpp>
 #include <rime_api.h>
 #include <rime/common.h>
 
@@ -81,7 +80,7 @@ struct List {
 
 class MappedFileImpl;
 
-class RIME_API MappedFile : boost::noncopyable {
+class RIME_API MappedFile {
  protected:
   explicit MappedFile(const string& file_name);
   virtual ~MappedFile();
@@ -106,6 +105,10 @@ class RIME_API MappedFile : boost::noncopyable {
   char* address() const;
 
  public:
+  // noncpyable
+  MappedFile(const MappedFile&) = delete;
+  MappedFile& operator=(const MappedFile&) = delete;
+
   bool Exists() const;
   bool IsOpen() const;
   void Close();
diff --git a/src/rime/dict/string_table.cc b/src/rime/dict/string_table.cc
index c3b68efed..d439a464d 100644
--- a/src/rime/dict/string_table.cc
+++ b/src/rime/dict/string_table.cc
@@ -5,15 +5,16 @@
 // 2014-07-04 GONG Chen <chen.sst@gmail.com>
 //
 
-#include <boost/iostreams/device/array.hpp>
-#include <boost/iostreams/stream.hpp>
+#include <sstream>
 #include <rime/common.h>
 #include <rime/dict/string_table.h>
 
 namespace rime {
 
 StringTable::StringTable(const char* ptr, size_t size) {
-  trie_.map(ptr, size);
+  std::stringstream stream;
+  stream.write(ptr, size);
+  stream >> trie_;
 }
 
 bool StringTable::HasKey(const string& key) {
@@ -106,10 +107,10 @@ void StringTableBuilder::Dump(char* ptr, size_t size) {
     LOG(ERROR) << "insufficient memory to dump string table.";
     return;
   }
-  namespace io = boost::iostreams;
-  io::basic_array_sink<char> sink(ptr, size);
-  io::stream<io::basic_array_sink<char>> stream(sink);
+
+  std::stringstream stream;
   stream << trie_;
+  stream.read(ptr, size);
 }
 
 }  // namespace rime
diff --git a/src/rime/dict/user_db.cc b/src/rime/dict/user_db.cc
index 5fe789588..e35019eea 100644
--- a/src/rime/dict/user_db.cc
+++ b/src/rime/dict/user_db.cc
@@ -5,8 +5,8 @@
 // 2011-11-02 GONG Chen <chen.sst@gmail.com>
 //
 #include <cstdlib>
+#include <sstream>
 #include <boost/algorithm/string.hpp>
-#include <boost/format.hpp>
 #include <rime/service.h>
 #include <rime/algo/dynamics.h>
 #include <rime/dict/text_db.h>
@@ -33,10 +33,12 @@ void UserDbValue::AppendElements(const DictEntry& entry) {
 }
 
 string UserDbValue::Pack() const {
-  return boost::str(elements.size() <= 1
-                        ? boost::format("c=%1% d=%2% t=%3%") % commits % dee % tick
-                        : boost::format("c=%1% d=%2% t=%3% e=%4%") %
-                              commits % dee % tick % boost::join(elements, "/"));
+  std::ostringstream packed;
+  packed << "c=" << commits << " d=" << dee << " t=" << tick;
+  if (elements.size() > 1) {
+	packed << " e=" << boost::join(elements, "/");
+  }
+  return packed.str();
 }
 
 bool UserDbValue::Unpack(const string& value) {
diff --git a/src/rime/gear/shape.cc b/src/rime/gear/shape.cc
index 37a078896..b6a16774e 100644
--- a/src/rime/gear/shape.cc
+++ b/src/rime/gear/shape.cc
@@ -5,7 +5,7 @@
 // 2013-07-02 GONG Chen <chen.sst@gmail.com>
 //
 #include <sstream>
-#include <boost/algorithm/string.hpp>
+#include <algorithm>
 #include <rime/context.h>
 #include <rime/engine.h>
 #include <rime/key_event.h>
@@ -17,7 +17,8 @@ void ShapeFormatter::Format(string* text) {
   if (!engine_->context()->get_option("full_shape")) {
     return;
   }
-  if (boost::all(*text, !boost::is_from_range('\x20', '\x7e'))) {
+  if (std::all_of(text->cbegin(), text->cend(),
+                  [](auto ch) { return (ch >= 0x20 && ch <= 0x7e); })) {
     return;
   }
   std::ostringstream oss;
diff --git a/src/rime/key_event.cc b/src/rime/key_event.cc
index ae1ecea70..bdfd9a114 100644
--- a/src/rime/key_event.cc
+++ b/src/rime/key_event.cc
@@ -5,7 +5,7 @@
 // 2011-04-20 GONG Chen <chen.sst@gmail.com>
 //
 #include <sstream>
-#include <boost/format.hpp>
+#include <iomanip>
 #include <rime/key_event.h>
 #include <rime/key_table.h>
 
@@ -36,15 +36,16 @@ string KeyEvent::repr() const {
     return modifiers.str() + name;
   }
   // no name :-| return its hex value
-  string value;
+  std::ostringstream value;
+  value << "0x" << std::setfill('0');
   if (keycode_ <= 0xffff) {
-    value = boost::str(boost::format("0x%4x") % keycode_);
+    value << std::setw(4) << std::hex << keycode_;
   } else if (keycode_ <= 0xffffff) {
-    value = boost::str(boost::format("0x%6x") % keycode_);
+    value << std::setw(6) << std::hex << keycode_;
   } else {
     return "(unknown)";  // invalid keycode
   }
-  return modifiers.str() + value;
+  return modifiers.str() + value.str();
 }
 
 bool KeyEvent::Parse(const string& repr) {
diff --git a/src/rime_api.cc b/src/rime_api.cc
index 23506f1d9..a7a8b260a 100644
--- a/src/rime_api.cc
+++ b/src/rime_api.cc
@@ -6,7 +6,6 @@
 //
 #include <cstring>
 #include <sstream>
-#include <boost/format.hpp>
 #include <rime/common.h>
 #include <rime/composition.h>
 #include <rime/config.h>
@@ -752,7 +751,9 @@ RIME_API Bool RimeConfigNext(RimeConfigIterator* iterator) {
       ++p->iter;
     if (p->iter == p->end)
       return False;
-    p->key = boost::str(boost::format("@%1%") % iterator->index);
+    std::ostringstream key;
+    key << "@" << iterator->index;
+    p->key = key.str();
     p->path = p->prefix + p->key;
     iterator->key = p->key.c_str();
     iterator->path = p->path.c_str();
diff --git a/test/config_compiler_test.cc b/test/config_compiler_test.cc
index 0c83c1fd7..330edd040 100644
--- a/test/config_compiler_test.cc
+++ b/test/config_compiler_test.cc
@@ -3,7 +3,7 @@
 // Distributed under the BSD License
 //
 
-#include <boost/format.hpp>
+#include <sstream>
 #include <gtest/gtest.h>
 #include <rime/component.h>
 #include <rime/config.h>
@@ -34,7 +34,9 @@ class RimeConfigCompilerTest : public RimeConfigCompilerTestBase {
 
 TEST_F(RimeConfigCompilerTest, IncludeLocalReference) {
   for (size_t i = 0; i < 4; ++i) {
-    auto prefix = boost::str(boost::format("include_local_reference/@%u/") % i);
+    std::ostringstream oss;
+    oss << "include_local_reference/@" << i << "/";
+    const auto& prefix(oss.str());
     EXPECT_TRUE(config_->IsNull(prefix + "__include"));
     string actual;
     EXPECT_TRUE(config_->GetString(prefix + "terrans/player", &actual));