diff --git a/content/pages/a_page.md b/content/pages/a_page.md
index 2c4339f..f37368f 100644
--- a/content/pages/a_page.md
+++ b/content/pages/a_page.md
@@ -11,4 +11,4 @@ template_engine jinja2
 
 <h2>Page 1</h2>
 
-<p>Go to <a href="{{ url_slug('page2') }}">page 2</a> </p>
\ No newline at end of file
+<p>Go to <a href="{{ url_for_slug('page2') }}">page 2</a> </p>
\ No newline at end of file
diff --git a/content/pages/another_page.md b/content/pages/another_page.md
index 281fd93..17f11b8 100644
--- a/content/pages/another_page.md
+++ b/content/pages/another_page.md
@@ -11,4 +11,4 @@ template_engine jinja2
 
 <h2> Page 2 </h2>
 
-<p>Go to <a href="{{ url_slug('page1') }}">page 1</a> </p>
+<p>Go to <a href="{{ url_for_slug('page1') }}">page 1</a> </p>
diff --git a/content/templates/jinja2/blocks/en/navbar.html b/content/templates/jinja2/blocks/en/navbar.html
index d2ddb7b..80f83a1 100644
--- a/content/templates/jinja2/blocks/en/navbar.html
+++ b/content/templates/jinja2/blocks/en/navbar.html
@@ -4,7 +4,7 @@
     CTA_LABEL="See pricing",
     CTA_TARGET="",
     CTA_URL="#pricing",
-    CHANGE_LANG_URL="fr-index",
+    CHANGE_LANG_URL="/fr-index.html",
     CHANGE_LANG_FLAG_URL="assets/img/lang-fr.svg",
     CHANGE_LANG_ALT="Version française" 
   ) }}
\ No newline at end of file
diff --git a/content/templates/jinja2/blocks/fr/navbar.html b/content/templates/jinja2/blocks/fr/navbar.html
index 29345f5..7f48327 100644
--- a/content/templates/jinja2/blocks/fr/navbar.html
+++ b/content/templates/jinja2/blocks/fr/navbar.html
@@ -4,7 +4,7 @@
     CTA_LABEL="Découvrir les tarifs",
     CTA_TARGET="",
     CTA_URL="#pricing",
-    CHANGE_LANG_URL="en-index",
+    CHANGE_LANG_URL="/en-index.html",
     CHANGE_LANG_FLAG_URL="assets/img/lang-gb.svg",
     CHANGE_LANG_ALT="English version" 
   ) }}
\ No newline at end of file
diff --git a/content/templates/jinja2/widgets/navbar.html b/content/templates/jinja2/widgets/navbar.html
index 445d1dc..dada97a 100644
--- a/content/templates/jinja2/widgets/navbar.html
+++ b/content/templates/jinja2/widgets/navbar.html
@@ -19,7 +19,7 @@
     <div class="navbar__container__right">
       <a class="btn btn-sm btn-primary" href="{{ CTA_URL }}"
          target="{{ CTA_TARGET }}">{{ CTA_LABEL }}</a>
-      <a href="{{ url_abs(CHANGE_LANG_URL) }}">
+      <a href="{{ url_for_slug_path(CHANGE_LANG_URL) }}">
         <img class="languageFlag" src="{{ static(CHANGE_LANG_FLAG_URL)}}" alt="{{ CHANGE_LANG_ALT }}"/>
       </a>
     </div>
diff --git a/jssg/jinja2.py b/jssg/jinja2.py
index 3589a9b..f8ad0ca 100644
--- a/jssg/jinja2.py
+++ b/jssg/jinja2.py
@@ -5,38 +5,84 @@
 
 from jssg.templatetags.filter_opengraph_metadata import filter_opengraph_metadata
 
-
 from jssg.models import Page
 
-def url_from_slug(slug) :
+import re
+
+def url_for_slug(slug) :
+    """
+    @param slug: the slug of the page to search
+    @return: the string of the url corresponding to the page
+    @error: raise an exception if the slug does not exist or it is not unique (eg same slug found in several folders)
+
+    >>> url_for_slug('index') # the slug exists and is unique
+    /en/index.html
+
+    >>> url_for_slug('index-duplicated') # the slug exists in several pages
+    Traceback (most recent call last):
+      ...
+    Exception: slug 'index-duplicated' is not unique, found in : [pages/fr-index.md, pages/en-index.md] ; use url_for_slug_path()
+
+    >>> url_for_slug('index-removed') # the slug does not exists
+    Traceback (most recent call last):
+      ...
+    Exception: slug 'index-removed' not found
+
+    """
+
     url = ""
-    pages_with_slug = ""
+    pages_with_slug = []
 
     for page in Page.load_glob(all=True) :
-        if page.slug == slug :
-            if pages_with_slug == "" :
-                url = "/" + page.dir + "/" + page.slug + ".html"
-            else :
+        if page.slug == slug : # the page exists
+            if pages_with_slug == [] : # the slug has not been found yet
+                if page.rel_folder_path != '' :
+                    url = "/" + page.rel_folder_path + "/" + page.slug + ".html"
+                else :
+                    url = "/" + page.slug + ".html"
+            else : # the slug already exists
                 url = ""
-            pages_with_slug += str(page.path.relative_to(page.page_dir.parent)) + ", "
+            pages_with_slug.append(str(page.path.relative_to(page.content_page_dir.parent)))
 
-    if url == "" and pages_with_slug != "" :
-        raise Exception("url_slug() : slug '%s' is not unique, found in : [%s] ; use url_abs()" % (slug, pages_with_slug[:-2]))
+    if url == "" and pages_with_slug != [] :
+        raise Exception("slug '%s' is not unique, found in : [%s] ; use url_for_slug_path()" % (slug, ", ".join(pages_with_slug)))
     elif url == "" :
-        raise Exception("url_slug() : slug '%s' not found" % slug)
+        raise Exception("slug '%s' not found" % slug)
     return url
 
-def url_absolute(url_path) :
-    dir = '/'.join(url_path.split('/')[:-1])
-    slug = ''.join((''.join(url_path.split('/')[-1])).split('.')[0])
+def url_for_slug_path(url_path) :
+    """
+    @param url_path: the url of the page to search (absolute path)
+    @return: the string of the url corresponding to the page
+    @error: raise an exception if the url is a dead link
+
+    >>> url_for_slug_path('/en/index.html') # the page exists
+    /en/index.html
+
+    >>> url_for_slug_path('/en/index-removed.html') # the page does not exist
+    Traceback (most recent call last):
+    ...
+    Exception: page for '/en/index-removed.html' url not found (dead link)
 
-    for page in Page.get_pages() :
-        if page["slug"] == slug and dir == "" :
-            return "/" + slug + ".html"
-        elif page["slug"] == slug and "dir" in page.keys() and page["dir"] == dir :
-            return "/" + dir + "/" + slug + ".html"
+    >>> url_for_slug_path('folder/index')
+    Traceback (most recent call last):
+      ...
+    Exception: url 'folder/index' is not valid ; correct urls are /<dir>/<slug>.html or /<slug.html>
+
+    """
+    # Valid url are /<dir>/<slug>.html or /<slug>.html
+    # Example: if url_path is "/tmp/folder/subfolder/thefile.html", then slug will be "thefile" and the dir will be "tmp/folder/subfolder"
+    try :
+        _, dir, slug = re.findall(r"(^|^/([a-zA-Z0-9-/]+))/([a-zA-Z0-9-]+)\.html", url_path)[0]
+    except :
+        raise Exception("url '%s' is not valid ; correct urls are /<dir>/<slug>.html or /<slug>.html" % url_path)
+
+    # Verify that the page exists
+    for page in Page.load_glob(all=True) :
+        if page.slug == slug and page.rel_folder_path == dir :
+            return url_path
 
-    raise Exception("url_abs() : page for %s url not found" % url_path)
+    raise Exception("page for '%s' url not found (dead link)" % url_path)
 
 def environment(**options):
     env = Environment(**options)
@@ -44,8 +90,8 @@ def environment(**options):
         {
             "static": static,
             "url": reverse,
-            "url_slug": url_from_slug,
-            "url_abs" : url_absolute
+            "url_for_slug": url_for_slug,
+            "url_for_slug_path" : url_for_slug_path
         }
     )
     env.filters.update(
diff --git a/jssg/models.py b/jssg/models.py
index 4439424..de227f4 100644
--- a/jssg/models.py
+++ b/jssg/models.py
@@ -238,13 +238,14 @@ def __init__(self, content: str, **metadata) -> None:
         except KeyError:
             self.slug = slugify(self.title)
 
-        self.page_dir = self.path
-        while (self.page_dir not in self.BASE_DIR) :
-            self.page_dir = self.page_dir.parent
+        self.content_page_dir = self.path
+        while (self.content_page_dir not in self.BASE_DIR) :
+            self.content_page_dir = self.content_page_dir.parent
 
-        self.dir = str(self.path.relative_to(self.page_dir).parent)
-        if self.dir == '.' :
-            self.dir = ''
+        # page folder path relative to its content_page_dir
+        self.rel_folder_path = str(self.path.relative_to(self.content_page_dir).parent)
+        if self.rel_folder_path == '.' :
+            self.rel_folder_path = ''
 
     @classmethod
     def load_page_with_slug(cls, slug: str, dir : str) -> "Page":
@@ -259,7 +260,7 @@ def load_glob(
     
     @classmethod
     def get_pages(cls) :
-        return ({"slug": p.slug} if p.dir == '' else {"dir": p.dir, "slug" : p.slug} for p in Page.load_glob(all = True))
+        return ({"slug": p.slug} if p.rel_folder_path == '' else {"dir": p.rel_folder_path, "slug" : p.slug} for p in Page.load_glob(all = True))
 
 
 class Post(Page):
@@ -285,7 +286,7 @@ def load_glob(
     
     @classmethod
     def get_posts(cls) :
-        return ({"slug": p.slug} if p.dir == '' else {"dir": p.dir, "slug" : p.slug} for p in Post.load_glob(all = True))
+        return ({"slug": p.slug} if p.rel_folder_path == '' else {"dir": p.rel_folder_path, "slug" : p.slug} for p in Post.load_glob(all = True))
 
 class Sitemap :
     BASE_DIR = settings.JFME_PAGES_DIRS + settings.JFME_POSTS_DIRS