diff --git a/README.md b/README.md
index 5200a3e..15a31ee 100644
--- a/README.md
+++ b/README.md
@@ -11,10 +11,12 @@ As this is still a WIP, here is a short list of what works and what still needs
 - [x] metadata parsing
 - [x] basic tests
 - [x] parsing markdown
-- [ ] generating html documents
+- [x] generating html documents
 - [ ] some nicer css styles
 - [ ] more sensible templates
 - [x] change yaml style metadata to toml
+- [ ] cli
+- [ ] perhaps someday gui?
 
 # What is this? 
 This is a small blog app. Basically a static site generator.
diff --git a/src/builder/builder.cpp b/src/builder/builder.cpp
new file mode 100644
index 0000000..8216505
--- /dev/null
+++ b/src/builder/builder.cpp
@@ -0,0 +1,43 @@
+#include "builder/builder.hpp"
+#include "config/config.hpp"
+#include "format/format.hpp"
+
+std::string build_index(const std::string &TEMPLATE, const Page &PAGE,
+                        const Information &INFORMATION) {
+  std::string result = TEMPLATE;
+  result = format_file(result, "{{lang}}", INFORMATION.config.general.lang);
+  result = format_file(result, "{{head}}", PAGE.head);
+  result = format_file(result, "{{header}}", PAGE.header);
+  result = format_file(result, "{{main}}", PAGE.main);
+  result = format_file(result, "{{footer}}", PAGE.footer);
+  return result;
+}
+
+std::string build_header(const std::string &TEMPLATE,
+                         const Information &INFORMATION) {
+  std::string result =
+      format_file(TEMPLATE, "{{title}}", INFORMATION.metadata.title);
+  ;
+
+  return result;
+}
+
+std::string build_head(const std::string &TEMPLATE,
+                       const Information &INFORMATION) {
+  std::string result =
+      format_file(TEMPLATE, "{{title}}", INFORMATION.metadata.title);
+  return result;
+}
+
+std::string build_footer(const std::string &TEMPLATE,
+                         const Information &INFORMATION) {
+  std::string result = TEMPLATE;
+  result =
+      format_file_conditionally(result, "{{if email}}", "{{endif}}",
+                                "{{email}}", INFORMATION.config.contact.email);
+
+  result = format_file_conditionally(result, "{{if signal}}", "{{endif}}",
+                                     "{{signal}}",
+                                     INFORMATION.config.contact.signal);
+  return result;
+}
diff --git a/src/builder/builder.hpp b/src/builder/builder.hpp
new file mode 100644
index 0000000..08c2373
--- /dev/null
+++ b/src/builder/builder.hpp
@@ -0,0 +1,22 @@
+#include "config/config.hpp"
+#include "markdown/markdown.hpp"
+
+struct Page {
+  std::string head;
+  std::string header;
+  std::string main;
+  std::string footer;
+};
+
+struct Information {
+  Config config;
+  Metadata metadata;
+};
+
+// @brief Function that builds index.html. It takes all the information from
+// `Page` struct that should be built before calling it.
+// @param TEMPLATE Template file that will be used to build index
+// @param PAGE Page struct with information on html tags
+// @return Built index.html in string
+std::string build_index(const std::string &TEMPLATE, const Page &PAGE,
+                        const Information &INFORMATION);
diff --git a/src/makefile b/src/makefile
index 0d73592..5d76770 100644
--- a/src/makefile
+++ b/src/makefile
@@ -9,7 +9,8 @@ SOURCES = main.cpp \
           config/config.cpp \
           format/format.cpp \
           markdown/markdown.cpp \
-		  io/io.cpp
+		  io/io.cpp \
+		  builder/builder.cpp
 
 OBJECTS = $(SOURCES:%.cpp=$(BUILD_DIR)/%.o)
 
@@ -17,7 +18,8 @@ TEST_SOURCES = tests.cpp \
                config/config.cpp \
                format/format.cpp \
                markdown/markdown.cpp \
-			   io/io.cpp
+			   io/io.cpp \
+			   builder/builder.cpp
 
 TEST_OBJECTS = $(TEST_SOURCES:%.cpp=$(BUILD_DIR)/%.o)
 
@@ -33,6 +35,7 @@ directories:
 	@mkdir -p $(BUILD_DIR)/format
 	@mkdir -p $(BUILD_DIR)/io
 	@mkdir -p $(BUILD_DIR)/markdown
+	@mkdir -p $(BUILD_DIR)/builder
 
 $(TARGET): $(OBJECTS)
 	$(CXX) $(CXXFLAGS) -o $@ $^ $(LIBS)
diff --git a/src/markdown/markdown.hpp b/src/markdown/markdown.hpp
index cff04b1..d55cbe1 100644
--- a/src/markdown/markdown.hpp
+++ b/src/markdown/markdown.hpp
@@ -1,3 +1,4 @@
+#pragma once
 #include <ctime>
 #include <optional>
 #include <string>
diff --git a/src/tests.cpp b/src/tests.cpp
index c2bc76d..4d61b81 100644
--- a/src/tests.cpp
+++ b/src/tests.cpp
@@ -1,3 +1,4 @@
+#include "builder/builder.hpp"
 #include "config/config.hpp"
 #include "format/format.hpp"
 #include "io/io.hpp"
@@ -128,6 +129,21 @@ This [should be clickable](https://example.com)
 - nine
 - six
 - nine)";
+
+constexpr const char *template_index = R"(<!DOCTYPE html>
+<html lang="{{lang}}">
+<head>
+    {{head}}
+</head>
+<body>
+    <header>{{header}}</header>
+    <main>
+        {{main}}
+    </main>
+    {{footer}}
+</body>
+</html>)";
+
 } // namespace TestFiles
 
 // IO tests
@@ -158,7 +174,7 @@ TEST_CASE("get_metadata function data correctness test") {
   Metadata result = get_metadata(TestFiles::post_md).value();
 
   std::string expected_author = "joseph";
-  struct tm datetime = {0};
+  struct tm datetime = {};
   datetime.tm_year = 2026 - 1900;
   datetime.tm_mon = 1 - 1;
   datetime.tm_mday = 1;
@@ -241,3 +257,37 @@ TEST_CASE("Test format_file_conditionally with empty tag") {
           format_file_conditionally(TestFiles::formatter_html_conditionally,
                                     "{{if tag}}", "{{endif}}", "{{tag}}", ""));
 }
+
+// Builder tests
+TEST_CASE("build_index correctly assembles the page", "[builder]") {
+  Config config;
+  config.general.lang = "pl";
+  Metadata metadata;
+
+  Information info;
+  info.config = config;
+  info.metadata = metadata;
+
+  Page page;
+  page.head = "<meta charset='utf-8'><title>Test</title>";
+  page.header = "<nav>Menu</nav>";
+  page.main = "<article>Treść wpisu</article>";
+  page.footer = "<footer>Stopka</footer>";
+
+  std::string expected_output = R"(<!DOCTYPE html>
+<html lang="pl">
+<head>
+    <meta charset='utf-8'><title>Test</title>
+</head>
+<body>
+    <header><nav>Menu</nav></header>
+    <main>
+        <article>Treść wpisu</article>
+    </main>
+    <footer>Stopka</footer>
+</body>
+</html>)";
+
+  std::string result = build_index(TestFiles::template_index, page, info);
+  REQUIRE(result == expected_output);
+}
diff --git a/templates/index.html b/templates/index.html
index aed8988..ae4a9bd 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -1,13 +1,18 @@
 <!DOCTYPE html>
 <html lang="{{lang}}">
+<head>
 {{head}}
+</head>
 <body>
+    <header>
     {{header}}
-
+    </header>
     <main>
-        <ol id="posts">
-            {{posts}}
-        </ol>
+        {{main}}
     </main>
+
+    <footer>
+        {{footer}}
+    </footer>
 </body>
 </html>