diff --git a/CMakeLists.txt b/CMakeLists.txt
index f3eacc8..5c6b139 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,6 +4,7 @@ option(ENABLE_ICONV "Use libiconv to convert encoding" ON)
 option(ENABLE_STANDALONE "Build utils standalone" OFF)
 option(ENABLE_CXX17 "Enable C++ 17" OFF)
 option(INSTALL_DEP_FILES "Install a file with dependences." OFF)
+option(ENABLE_SSL "Enable SSL" OFF)
 
 if (ENABLE_STANDALONE)
     project(utils)
@@ -23,6 +24,11 @@ if (ENABLE_ICONV)
     find_package(Iconv)
 endif()
 
+if (ENABLE_SSL)
+    find_package(OpenSSL 3.0.0 REQUIRED)
+    set(HAVE_OPENSSL 1)
+endif()
+
 if (Iconv_FOUND)
     set(HAVE_ICONV 1)
 endif()
@@ -82,6 +88,7 @@ set(SOURCE_FILE
     c_linked_list.cpp
     file_reader.c
     urlparse.cpp
+    http_client.cpp
 )
 set(SOURCE_FILE_HEADERS
     cfileop.h
@@ -101,6 +108,7 @@ set(SOURCE_FILE_HEADERS
     c_linked_list.h
     file_reader.h
     urlparse.h
+    http_client.h
 )
 
 add_library(utils STATIC ${SOURCE_FILE} ${SOURCE_FILE_HEADERS})
@@ -118,6 +126,12 @@ if (INSTALL_DEP_FILES)
         target_link_libraries(utils shell32)
     endif()
 endif()
+if (WIN32)
+    target_link_libraries(utils Ws2_32)
+endif()
+if (ENABLE_SSL)
+    target_link_libraries(utils OpenSSL::SSL OpenSSL::Crypto)
+endif()
 if (ENABLE_CXX17)
     target_compile_features(utils PRIVATE cxx_std_17)
 endif()
diff --git a/cstr_util.c b/cstr_util.c
index c007b49..7f2afb6 100644
--- a/cstr_util.c
+++ b/cstr_util.c
@@ -92,6 +92,21 @@ int cstr_tolowercase(const char* str, size_t input_len, char** output) {
     return 1;
 }
 
+int cstr_touppercase(const char* str, size_t input_len, char** output) {
+    if (!str || !output) return 0;
+    if (!input_len) input_len = strlen(str);
+    if (input_len == (size_t)-1) return 0;
+    char* tmp = malloc(input_len + 1);
+    if (!tmp) return 0;
+    size_t i = 0;
+    for (; i < input_len; i++) {
+        tmp[i] = toupper(str[i]);
+    }
+    tmp[input_len] = 0;
+    *output = tmp;
+    return 1;
+}
+
 uint32_t cstr_read_uint32(const uint8_t* bytes, int big) {
     if (!bytes) return 0;
     return big ? (bytes[0] << 24) + (bytes[1] << 16) + (bytes[2] << 8) + bytes[3] : bytes[0] + (bytes[1] << 8) + (bytes[2] << 16) + (bytes[3] << 24);
diff --git a/cstr_util.h b/cstr_util.h
index 4dfc52f..1b03e61 100644
--- a/cstr_util.h
+++ b/cstr_util.h
@@ -27,6 +27,14 @@ int cstr_is_integer(const char* str, int allow_sign);
  * @return 1 if successed otherwise 0.
 */
 int cstr_tolowercase(const char* str, size_t input_len, char** output);
+/**
+ * @brief Convert string to uppercase
+ * @param str Origin string
+ * @param input_len The length of origin string. If is 0, strlen will be called to calculate length.
+ * @param output Output string. Need free memory by calling free.
+ * @return 1 if successed otherwise 0.
+*/
+int cstr_touppercase(const char* str, size_t input_len, char** output);
 /**
  * @brief Convert bytes to uint32
  * @param bytes Bytes (at least 4 bytes)
diff --git a/http_client.cpp b/http_client.cpp
new file mode 100644
index 0000000..70ba1ee
--- /dev/null
+++ b/http_client.cpp
@@ -0,0 +1,423 @@
+#include "http_client.h"
+
+#ifndef _WIN32
+#include <unistd.h>
+#endif
+
+#include "err.h"
+#include "str_util.h"
+
+#include <stdexcept>
+#include <string>
+
+#if _WIN32
+static bool inited = false;
+static WSADATA wsaData = { 0 };
+#endif
+
+#if HAVE_OPENSSL
+static bool ssl_inited = false;
+#endif
+
+AIException::AIException(int code) {
+    this->code = code;
+}
+
+const char* AIException::what() {
+#if _WIN32
+    return gai_strerrorA(this->code);
+#else
+    return gai_strerror(this->code);
+#endif
+}
+
+std::string decodeURIComponent(std::string str) {
+    std::string re;
+    for (size_t i = 0; i < str.length(); i++) {
+        if (str[i] == '%') {
+            if (i + 2 >= str.length()) {
+                throw std::runtime_error("Invalid Percent-encoding");
+            }
+            char buf[3] = { str[i + 1], str[i + 2], 0 };
+            int c = strtol(buf, nullptr, 16);
+            re += (char)c;
+            i += 2;
+        } else {
+            re += str[i];
+        }
+    }
+    return re;
+}
+
+std::string encodeURIComponent(std::string str) {
+    std::string re;
+    for (size_t i = 0; i < str.length(); i++) {
+        if (str[i] == ' ') {
+            re += '+';
+        } else if (str[i] == '-' || str[i] == '_' || str[i] == '.' || str[i] == '~' ||
+            (str[i] >= 'a' && str[i] <= 'z') ||
+            (str[i] >= 'A' && str[i] <= 'Z') ||
+            (str[i] >= '0' && str[i] <= '9')) {
+            re += str[i];
+        } else {
+            char buf[4] = { '%', 0 };
+            snprintf(buf + 1, 3, "%02X", (unsigned char)str[i]);
+            re += buf;
+        }
+    }
+    return re;
+}
+
+SocketError::SocketError() {
+#if _WIN32
+    this->code = WSAGetLastError();
+#else
+    this->code = errno;
+#endif
+#if _WIN32
+    if (!err::get_winerror(this->message, this->code)) {
+#else
+    if (!err::get_errno_message(this->message, this->code)) {
+#endif
+        char buf[32];
+        snprintf(buf, 32, "Unknown error %d", this->code);
+        this->message = std::string(buf);
+    }
+}
+
+const char* SocketError::what() {
+    return this->message.c_str();
+}
+
+Socket::Socket(std::string host, std::string protocol) {
+    this->host = host;
+    this->protocol = protocol;
+#if HAVE_OPENSSL
+    if (protocol == "https") {
+        return;
+    }
+#endif
+    addrinfo hints = { 0 };
+    hints.ai_family = AF_UNSPEC;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_protocol = IPPROTO_TCP;
+    int re = getaddrinfo(host.c_str(), protocol.c_str(), &hints, &this->addr);
+    if (re) {
+        throw AIException(re);
+    }
+}
+
+Socket::~Socket() {
+#if HAVE_OPENSSL
+    if (this->ssl_ctx) {
+        SSL_CTX_free(this->ssl_ctx);
+        this->ssl_ctx = nullptr;
+    }
+    if (this->web) {
+        BIO_free_all(this->web);
+        this->web = nullptr;
+    }
+#endif
+    this->close();
+    if (this->addr) {
+        freeaddrinfo(this->addr);
+        this->addr = nullptr;
+    }
+}
+
+void Socket::connect() {
+#if HAVE_OPENSSL
+    if (this->protocol == "https") {
+        const SSL_METHOD* method = SSLv23_client_method();
+        if (!method) {
+            throw std::runtime_error("SSLv23_client_method failed");
+        }
+        this->ssl_ctx = SSL_CTX_new(method);
+        if (!this->ssl_ctx) {
+            throw std::runtime_error("SSL_CTX_new failed");
+        }
+        const long flags = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3 | SSL_OP_NO_COMPRESSION;
+        SSL_CTX_set_options(this->ssl_ctx, flags);
+        this->web = BIO_new_ssl_connect(this->ssl_ctx);
+        if (!this->web) {
+            throw std::runtime_error("BIO_new_ssl_connect failed");
+        }
+        int res =BIO_set_conn_hostname(this->web, this->host.c_str());
+        if (res == -1) {
+            throw std::runtime_error("BIO_set_conn_hostname failed");
+        }
+        BIO_get_ssl(this->web, &this->ssl);
+        if (!this->ssl) {
+            throw std::runtime_error("BIO_get_ssl failed");
+        }
+        res = SSL_set_tlsext_host_name(this->ssl, this->host.c_str());
+        if (res == -1) {
+            throw std::runtime_error("SSL_set_tlsext_host_name failed");
+        }
+        res = BIO_do_connect(this->web);
+        if (res != 1) {
+            throw std::runtime_error("BIO_do_connect failed");
+        }
+        res = BIO_do_handshake(this->web);
+        if (res != 1) {
+            throw std::runtime_error("BIO_do_handshake failed");
+        }
+        return;
+    }
+#endif
+    if (this->socket != -1 || !this->addr) {
+        return;
+    }
+    this->socket = ::socket(this->addr->ai_family, this->addr->ai_socktype, this->addr->ai_protocol);
+#if _WIN32
+    if (this->socket == INVALID_SOCKET) {
+#else
+    if (this->socket == -1) {
+#endif
+        throw SocketError();
+    }
+    int re = ::connect(this->socket, this->addr->ai_addr, this->addr->ai_addrlen);
+#if _WIN32
+    if (re == SOCKET_ERROR) {
+#else
+    if (re == -1) {
+#endif
+        throw SocketError();
+    }
+}
+
+size_t Socket::send(const char* data, size_t len, int flags) {
+#if HAVE_OPENSSL
+    if (this->protocol == "https") {
+        int sented = BIO_write(this->web, data, (int)len);
+        if (sented <= 0) {
+            throw std::runtime_error("BIO_write failed");
+        }
+        return sented;
+    }
+#endif
+    if (this->socket == -1) {
+        throw std::runtime_error("Socket not connected");
+    }
+#if _WIN32
+    int sented = ::send(this->socket, data, (int)len, flags);
+    if (sented == SOCKET_ERROR) {
+#else
+    ssize_t sented = ::send(this->socket, data, len, flags);
+    if (sented == -1) {
+#endif
+        throw SocketError();
+    }
+    return sented;
+}
+
+size_t Socket::send(std::string data, int flags) {
+    return this->send(data.c_str(), data.length(), flags);
+}
+
+size_t Socket::recv(char* data, size_t len, int flags) {
+#if HAVE_OPENSSL
+    if (this->protocol == "https") {
+        int recved = BIO_read(this->web, data, (int)len);
+        if (recved <= 0) {
+            throw std::runtime_error("BIO_read failed");
+        }
+        return recved;
+    }
+#endif
+    if (this->socket == -1) {
+        throw std::runtime_error("Socket not connected");
+    }
+#if _WIN32
+    int recved = ::recv(this->socket, data, (int)len, flags);
+    if (recved == SOCKET_ERROR) {
+#else
+    ssize_t recved = ::recv(this->socket, data, len, flags);
+    if (recved == -1) {
+#endif
+        throw SocketError();
+    }
+    return recved;
+}
+
+std::string Socket::recv(size_t len, int flags) {
+    char* buf = new char[len];
+    try {
+        size_t recved = this->recv(buf, len, flags);
+        std::string re(buf, recved);
+        delete[] buf;
+        return re;
+    } catch (std::exception& e) {
+        delete[] buf;
+        throw e;
+    }
+}
+
+void Socket::close() {
+    if (this->socket != -1 && !closed) {
+#if _WIN32
+        closesocket(this->socket);
+#else
+        ::close(this->socket);
+#endif
+        closed = true;
+    }
+}
+
+Request::Request(std::string host, std::string path, std::string method, HeaderMap headers, HttpClientOptions options) {
+    this->host = host;
+    this->path = path;
+    this->method = method;
+    this->headers = headers;
+    this->options = options;
+}
+
+void Request::send() {
+    std::string data;
+    data += this->method + " " + this->path + " HTTP/1.1\r\n";
+    auto hasBody = !this->body || !this->body->isFinished();
+    if (hasBody) {
+        auto type = this->body->contentType();
+        if (!type.empty()) {
+            this->headers["Content-Type"] = type;
+        }
+        if (this->body->hasLength()) {
+            this->headers["Content-Length"] = std::to_string(this->body->length());
+        }
+    }
+    for (auto& header : this->headers) {
+        data += header.first + ": " + header.second + "\r\n";
+    }
+    data += "\r\n";
+    printf("%s", data.c_str());
+#if HAVE_OPENSSL
+    Socket socket(this->host, this->options.https ? "https" : "http");
+#else
+    Socket socket(this->host, "http");
+#endif
+    socket.connect();
+    socket.send(data);
+    if (hasBody) {
+        while (!this->body->isFinished()) {
+            char buf[1024];
+            size_t len = this->body->pullData(buf, 1024);
+            socket.send(buf, len, 0);
+            printf("%s", std::string(buf, len).c_str());
+        }
+        socket.send("\r\n");
+    }
+    auto s = socket.recv(10240);
+    printf("%s\n", s.c_str());
+}
+
+HttpClient::HttpClient(std::string host) {
+    this->host = host;
+#if _WIN32
+    if (!inited) {
+        WSAStartup(MAKEWORD(2, 2), &wsaData);
+        inited = true;
+    }
+#endif
+#if HAVE_OPENSSL
+    if (!ssl_inited) {
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+        SSL_library_init();
+#else
+        SSL_load_error_strings();
+#endif
+        ssl_inited = true;
+    }
+#endif
+    this->headers["Host"] = host;
+    this->headers["User-Agent"] = "simple-http-client";
+    this->headers["Accept"] = "*/*";
+}
+
+Request HttpClient::request(std::string path, std::string method) {
+    return Request(this->host, path, method, this->headers, this->options);
+}
+
+void HttpFullBody::pull() {
+    if (!this->pulled) {
+        this->buff = this->body();
+        this->len = this->buff.length();
+        this->pulled = true;
+    }
+}
+
+size_t HttpFullBody::pullData(char* buf, size_t len) {
+    this->pull();
+    size_t rlen = std::min(this->buff.length(), len);
+    memcpy(buf, this->buff.c_str(), rlen);
+    this->buff = this->buff.substr(rlen);
+    return rlen;
+}
+
+bool HttpFullBody::isFinished() {
+    this->pull();
+    return this->buff.length() == 0;
+}
+
+bool HttpFullBody::hasLength() {
+    return true;
+}
+
+std::string HttpFullBody::contentType() {
+    return "";
+}
+
+size_t HttpFullBody::length() {
+    this->pull();
+    return this->len;
+}
+
+QueryData::QueryData() {}
+
+QueryData::QueryData(std::string data) {
+    auto list = str_util::str_split(data, "&");
+    for (auto& item : list) {
+        auto kv = str_util::str_splitv(item, "=", 2);
+        auto k = decodeURIComponent(kv[0]);
+        auto v = decodeURIComponent(kv[1]);
+        this->append(k, v);
+    }
+}
+
+std::string QueryData::contentType() {
+    return "application/x-www-form-urlencoded";
+}
+
+std::string QueryData::toQuery() {
+    std::string re;
+    for (auto& item : this->data) {
+        for (auto& v : item.second) {
+            if (re.length() > 0) {
+                re += "&";
+            }
+            re += encodeURIComponent(item.first) + "=" + encodeURIComponent(v);
+        }
+    }
+    return re;
+}
+
+void QueryData::append(std::string key, std::string value) {
+    if (this->data.find(key) != this->data.end()) {
+        this->data[key].push_back(value);
+    } else {
+        this->data[key] = std::vector<std::string>({ value });
+    }
+}
+
+void QueryData::set(std::string key, std::string value) {
+    this->data[key] = std::vector<std::string>({ value });
+}
+
+std::string QueryData::body() {
+    return this->toQuery();
+}
+
+Request::~Request() {
+    if (this->body) {
+        delete this->body;
+    }
+}
diff --git a/http_client.h b/http_client.h
new file mode 100644
index 0000000..781232e
--- /dev/null
+++ b/http_client.h
@@ -0,0 +1,162 @@
+#ifndef _UTIL_HTTP_CLIENT_H
+#define _UTIL_HTTP_CLIENT_H
+
+#include <stddef.h>
+#include <string>
+#include <map>
+#include <memory>
+#include <vector>
+#include "cstr_util.h"
+#include "utils_config.h"
+
+#if _WIN32
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#else
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#endif
+
+#if HAVE_OPENSSL
+#include "openssl/ssl.h"
+#endif
+
+struct HeaderNameCompare {
+    bool operator()(const std::string& a, const std::string& b) const {
+        return cstr_stricmp(a.c_str(), b.c_str()) < 0;
+    }
+};
+
+typedef std::map<std::string, std::string, HeaderNameCompare> HeaderMap;
+
+std::string decodeURIComponent(std::string str);
+
+class HttpClientOptions {
+public:
+    bool https = false;
+};
+
+class HttpBody {
+public:
+    virtual size_t pullData(char* buf, size_t len) = 0;
+    virtual bool isFinished() = 0;
+    virtual std::string contentType() = 0;
+    virtual bool hasLength() = 0;
+    virtual size_t length() = 0;
+};
+
+class HttpFullBody: public HttpBody {
+public:
+    virtual size_t pullData(char* buf, size_t len);
+    virtual bool isFinished();
+    virtual bool hasLength();
+    virtual std::string contentType();
+    virtual size_t length();
+protected:
+    virtual std::string body() = 0;
+private:
+    void pull();
+    std::string buff;
+    bool pulled;
+    size_t len;
+};
+
+class QueryData: public HttpFullBody {
+public:
+    QueryData();
+    QueryData(std::string data);
+    std::string contentType();
+    std::map<std::string, std::vector<std::string>> data;
+    std::string toQuery();
+    void append(std::string key, std::string value);
+    void set(std::string key, std::string value);
+protected:
+    std::string body();
+};
+
+class AIException: std::exception {
+public:
+    AIException(int code);
+    const char* what();
+private:
+    int code;
+};
+
+class SocketError: std::exception {
+public:
+    SocketError();
+    const char* what();
+private:
+    int code;
+    std::string message;
+};
+
+class Socket {
+public:
+    Socket(std::string host, std::string protocol);
+    ~Socket();
+    void connect();
+    size_t send(const char* data, size_t len, int flags = 0);
+    template<size_t T>
+    size_t send(const char(&data)[T], int flags = 0) {
+        return this->send(data, T, flags);
+    }
+    size_t send(std::string data, int flags = 0);
+    size_t recv(char* data, size_t len, int flags = 0);
+    template<size_t T>
+    size_t recv(char(&data)[T], int flags = 0) {
+        return this->recv(data, T, flags);
+    }
+    std::string recv(size_t len, int flags = 0);
+    void close();
+private:
+#if HAVE_OPENSSL
+    SSL_CTX* ssl_ctx = nullptr;
+    BIO* web = nullptr;
+    SSL* ssl = nullptr;
+#endif
+    std::string host;
+    std::string protocol;
+    int socket = -1;
+    bool closed = false;
+    addrinfo* addr = nullptr;
+};
+
+class Request {
+public:
+    Request(std::string host, std::string path, std::string method, HeaderMap headers, HttpClientOptions options);
+    ~Request();
+    void send();
+    HeaderMap headers;
+    HttpClientOptions options;
+    void setBody(HttpBody* body) {
+        if (this->body != nullptr) delete this->body;
+        this->body = body;
+    }
+private:
+    HttpBody* body = nullptr;
+    std::string host;
+    std::string path;
+    std::string method;
+};
+
+class Response {
+public:
+    Response(Request req, Socket socket);
+private:
+    Request req;
+    Socket socket;
+};
+
+class HttpClient {
+public:
+    HttpClient(std::string host);
+    Request request(std::string path, std::string method);
+    HttpClientOptions options;
+    HeaderMap headers;
+private:
+    std::string host;
+};
+
+#endif
diff --git a/str_util.cpp b/str_util.cpp
index daf79de..20edb4c 100644
--- a/str_util.cpp
+++ b/str_util.cpp
@@ -18,6 +18,18 @@ bool str_util::tolowercase(std::string ori, std::string& result) {
     }
 }
 
+bool str_util::touppercase(std::string ori, std::string& result) {
+    char* tmp = nullptr;
+    auto re = cstr_touppercase(ori.c_str(), ori.length(), &tmp);
+    if (re) {
+        result = std::string(tmp, ori.length());
+        free(tmp);
+        return true;
+    } else {
+        return false;
+    }
+}
+
 std::string str_util::str_replace(std::string input, std::string pattern, std::string new_content) {
     auto loc = input.find(pattern, 0);
     auto len = pattern.length();
diff --git a/str_util.h b/str_util.h
index 48529e2..156fa64 100644
--- a/str_util.h
+++ b/str_util.h
@@ -12,6 +12,13 @@ namespace str_util {
      * @return true if successed.
     */
     bool tolowercase(std::string ori, std::string& result);
+    /**
+     * @brief Convert string to uppercase
+     * @param ori Origin string
+     * @param result Output string.
+     * @return true if successed.
+    */
+    bool touppercase(std::string ori, std::string& result);
     /**
      * @brief Replace all pattern to new_content
      * @param input Input string
diff --git a/utils_config.h.in b/utils_config.h.in
index e9d3027..5181966 100644
--- a/utils_config.h.in
+++ b/utils_config.h.in
@@ -17,3 +17,4 @@
 #cmakedefine HAVE__STRNICMP @HAVE__STRNICMP@
 #cmakedefine HAVE_STRNCASECMP @HAVE_STRNCASECMP@
 #cmakedefine HAVE_FCLOSEALL @HAVE_FCLOSEALL@
+#cmakedefine HAVE_OPENSSL @HAVE_OPENSSL@