diff --git a/inc/myco.js b/inc/myco.js
index 4682315..8cd1f7c 100644
--- a/inc/myco.js
+++ b/inc/myco.js
@@ -133,12 +133,10 @@ view_home=function() {
 on_home_grp_cat_btn_click=function(e) {
   grp_id=$(e.target).parents('div.btn-group').data('grp');
   grp=groups[grp_id];
-  console.log(grp.getCategories());
   ul=$('#grp_cat_modal ul');
   html="";
-  cats=grp.getCategories();
-  for(cid in cats) {
-    html+="<li><span class='cat-color' style='background-color: "+cats[cid]['color']+"'></span> "+cats[cid]['name']+"</li>";
+  for(cid in grp.categories) {
+    html+="<li><span class='cat-color' style='background-color: "+grp.categories[cid]['color']+"'></span> "+grp.categories[cid]['name']+"</li>";
   }
   ul.html(html);
   $('#grp_cat_modal').modal('show');
@@ -191,9 +189,8 @@ show_contributions=function(group,contributor_email) {
     sum=0;
     for (idx in contributions) {
       var cat='';
-      console.log(contributions[idx].categorie);
-      if (contributions[idx].categorie && jQuery.type(group.categories[contributions[idx].categorie])) {
-		cat='<br/><span class="categorie"><span class="cat-color" style="background-color: '+group.categories[contributions[idx].categorie]['color']+'"></span> '+group.categories[contributions[idx].categorie]['name']+"</span>";
+      if (contributions[idx].category && jQuery.type(group.categories[contributions[idx].category])) {
+		cat='<br/><span class="category"><span class="cat-color" style="background-color: '+group.categories[contributions[idx].category]['color']+'"></span> '+group.categories[contributions[idx].category]['name']+"</span>";
 	  }
       col_actions='<td><div class="btn-group" data-uuid="'+contributions[idx].uuid+'"><button type="button" class="btn btn-default contribution_edit_btn"><span class="glyphicon glyphicon-edit"></span></button><button type="button" class="btn btn-default contribution_delete_btn"><span class="glyphicon glyphicon-trash"></span></button></div></td>';
       tbody.append('<tr><td>'+contributions[idx].getTitle()+cat+'</td><td>'+contributions[idx].cost.toFixed(2)+' €<br/><span class="date">'+moment(contributions[idx].date).format('DD/MM/YYYY')+'</span></td>'+col_actions+'</tr>');
@@ -399,7 +396,7 @@ on_show_add_contribution_modal=function(e) {
   for (u in group.categories) {
 	cats+="<option value='"+u+"'>"+group.categories[u]['name']+"</option>";
   }
-  $('#add_contribution_modal #add_contribution_categorie').html(cats);
+  $('#add_contribution_modal #add_contribution_category').html(cats);
   $('#add_contribution_modal #add_contribution_title').focus();
 }
 
@@ -458,9 +455,9 @@ on_valid_add_contribution_modal=function(e) {
     date=new Date();
   }
   
-  var cat=$('#add_contribution_categorie')[0].value;
+  var cat=$('#add_contribution_category')[0].value;
   if (cat != '' && !jQuery.type(group.categories[cat])) {
-	alert('Categorie incorrect');
+	alert('Category incorrect');
 	return;
   }
   
@@ -505,8 +502,8 @@ on_contribution_edit_btn_click=function(e) {
   $('#add_contribution_modal #add_contribution_title')[0].value=contribution.getTitle();
   $('#add_contribution_modal #add_contribution_cost')[0].value=contribution.cost;
   $('#add_contribution_modal #add_contribution_date')[0].value=moment(contribution.date).format('DD/MM/YYYY');
-  if (contribution.categorie) {
-	$('#add_contribution_modal #add_contribution_categorie')[0].value=contribution.categorie;
+  if (contribution.category) {
+	$('#add_contribution_modal #add_contribution_category')[0].value=contribution.category;
   }
   $('#add_contribution_modal #edit_uuid')[0].value=contribution_uuid;
   $('#add_contribution_modal').modal('show');
diff --git a/inc/myco_objects.js b/inc/myco_objects.js
index 159e6cb..598d38d 100644
--- a/inc/myco_objects.js
+++ b/inc/myco_objects.js
@@ -122,6 +122,7 @@ function Group(uuid,name,data) {
   this.contributions={};
   this.deletedContributions={};
   this.categories={};
+  this.deletedCategories={};
 
   this.isGroup=function() {
     return true;
@@ -136,6 +137,10 @@ function Group(uuid,name,data) {
     for (uuid in this.contributions) {
       contributions[uuid]=this.contributions[uuid].export();
     }
+    var categories={}
+    for (uuid in this.categories) {
+      categories[uuid]=this.categories[uuid].export();
+    }
     return {
       'uuid': this.uuid,
       'name': encodeURIComponent(this.name),
@@ -143,7 +148,8 @@ function Group(uuid,name,data) {
       'deletedContributors': this.deletedContributors,
       'contributions': contributions,
       'deletedContributions': this.deletedContributions,
-      'categories': this.categories
+      'categories': categories,
+      'deletedCategories': this.deletedCategories
     };
   }
 
@@ -206,6 +212,13 @@ function Group(uuid,name,data) {
     delete this.contributors[email];
     this.contributors[c.email]=c;
   }
+  
+  this.importContributor=function(data) {
+    return new Contributor(
+      decodeURIComponent(data.name),
+      data.email
+    );
+  }
 
   /*
    * Contributions
@@ -240,7 +253,7 @@ function Group(uuid,name,data) {
           this.deletedContributions[uuid].cost,
           decodeURIComponent(this.deletedContributions[uuid].title),
           this.deletedContributions[uuid].date,
-          this.deletedContributions[uuid].categorie,
+          this.deletedContributions[uuid].category,
           uuid,
           this.deletedContributions[uuid].lastChange
         ));
@@ -281,24 +294,50 @@ function Group(uuid,name,data) {
     delete this.deletedContributions[uuid];
   }
 
-  this.importContributor=function(data) {
-    return new Contributor(
-      decodeURIComponent(data.name),
-      data.email
-    );
-  }
-
   this.importContribution=function(data) {
     return new Contribution(
       this.contributorByEmail(data.contributor),
       data.cost,
       decodeURIComponent(data.title),
       data.date,
-      data.categorie,
+      data.category,
       data.uuid,
       data.lastChange
     );
   }
+  
+  /*
+   * Categories
+   */
+
+  this.addCategory=function(c) {
+    this.categories[c.uuid]=c;
+  }
+
+  this.updateCategory=function(uuid,c) {
+    c.uuid=uuid;
+    this.categories[uuid]=c;
+  }
+
+  this.deleteCategory=function(uuid,time) {
+    this.categories[uuid].lastChange=time || new Date().getTime();
+    this.deletedCategory[uuid]=this.categories[uuid].export();
+    delete this.categories[uuid];
+  }
+
+  this.restoreCategory=function(uuid) {
+    this.deletedCategory[uuid].lastChange=new Date().getTime();
+    this.categories[uuid]=this.importCategory(this.deletedCategory[uuid]);
+    delete this.deletedCategory[uuid];
+  }
+
+  this.importCategory=function(data) {
+    return new Category(
+      decodeURIComponent(data.name),
+      data.color,
+      data.lastChange
+    );
+  }
 
   /*
    * Balance
@@ -339,13 +378,6 @@ function Group(uuid,name,data) {
     };
   }
 
-  /*
-   * Categories
-   */
-  this.getCategories=function() {
-    return this.categories;
-  }
-
   /*
    * Contructor
    */
@@ -373,12 +405,10 @@ function Group(uuid,name,data) {
           this.deletedContributions[uuid]=data.deletedContributions[uuid];
         }
       }
+      console.log(data.categories);
       if (jQuery.type(data.categories) == 'object') {
-        for (cid in data.categories) {
-          if (jQuery.type(data.categories[cid]['color'])!='string') {
-            data.categories[cid]['color']='#'+(0x1000000+(Math.random())*0xffffff).toString(16).substr(1,6);
-          }
-          this.categories[cid]=data.categories[cid];
+        for (uuid in data.categories) {
+          this.categories[uuid]=this.importCategory(data.categories[uuid]);
         }
       }
       else {
@@ -393,14 +423,17 @@ function Group(uuid,name,data) {
           'Cadeau': '#a700fa'
         };
         for (c in categories) {
-		  this.categories[generate_uuid()]={
-	        'name': c,
-	        'color': categories[c]
-		  };	
+		  this.categories[generate_uuid()]=new Category(c,categories[c]);
 	    }
       }
+      if (jQuery.type(data.deletedCategories) == 'object') {
+        for (uuid in data.deletedCategories) {
+          this.deletedCategories[uuid]=data.deletedCategories[uuid];
+        }
+      }
     }
     catch (e) {
+	  console.log(e);
       alert('Une erreur est survenue en chargeant le groupe '+this.name+' depuis le cache');
     }
   }
@@ -417,6 +450,19 @@ function Contributor(name,email) {
   }
 }
 
+function Category(name,color,lastChange) {
+  this.name=name;
+  this.color=color || '#'+(0x1000000+(Math.random())*0xffffff).toString(16).substr(1,6);
+  this.lastChange=lastChange || new Date().getTime();
+  this.export=function() {
+    return {
+      'name': encodeURIComponent(this.name),
+      'color': this.color,
+      'lastChange': this.lastChange
+    };
+  }
+}
+
 function Contribution(contributor,cost,title,date,cat,uuid,lastChange) {
   this.contributor=contributor;
   this.cost=cost;
@@ -426,7 +472,7 @@ function Contribution(contributor,cost,title,date,cat,uuid,lastChange) {
   }
   this.date=date;
   this.uuid=uuid || generate_uuid();
-  this.categorie=cat;
+  this.category=cat;
   this.lastChange=lastChange || new Date().getTime();
   this.export=function() {
     return {
@@ -435,7 +481,7 @@ function Contribution(contributor,cost,title,date,cat,uuid,lastChange) {
       'cost': this.cost,
       'title': encodeURIComponent(this.title),
       'date': this.date.getTime(),
-      'categorie': this.categorie,
+      'category': this.category,
       'lastChange': this.lastChange,
     };
   }
diff --git a/index.html b/index.html
index 3defa93..75b4a0b 100644
--- a/index.html
+++ b/index.html
@@ -55,7 +55,7 @@ body{
   text-transform: capitalize;
 }
 
-#view-group span.date, #view-group span.categorie {
+#view-group span.date, #view-group span.category {
   color: #999;
   font-size: 0.8em;
   font-style: italic;
@@ -408,7 +408,7 @@ span.cat-color {
           <div class="form-group">
             <div class="input-group">
               <span class="input-group-addon">Catégorie </span>
-              <select id='add_contribution_categorie' class="form-control"></select>
+              <select id='add_contribution_category' class="form-control"></select>
             </div>
           </div>
           <div class="form-group">