diff --git a/TODO b/TODO
index e69de29..a759652 100644
--- a/TODO
+++ b/TODO
@@ -0,0 +1,7 @@
+* use flask.instance_path to get/store configuration. See http://flask.pocoo.org/docs/config/#instance-folders
+* Attach the current projec to g and modify the url_for to use it. http://flask.pocoo.org/docs/patterns/urlprocessors/
+* Use class based views to factorize the code if there is some code to factorize, see http://flask.pocoo.org/docs/views/
+* Use request.args.get('next') to redirect when authenticating
+* Move the flask app to __init__.py (http://flask.pocoo.org/docs/patterns/packages/)
+* Eventually move the url definition into a specific section
+* Render templates automatically using a decorator. see http://stackoverflow.com/questions/7054099/using-flask-blueprint-for-some-static-pages/7056374#7056374
diff --git a/budget/templates/add_bill.html b/budget/templates/add_bill.html
index d844b6a..5b3a768 100644
--- a/budget/templates/add_bill.html
+++ b/budget/templates/add_bill.html
@@ -1,14 +1,14 @@
 {% extends "layout.html" %}
 
 {% block top_menu %}
-<a href="{{ url_for('list_bills', project_id=project.id) }}">Back to the list</a>
+<a href="{{ url_for('list_bills') }}">Back to the list</a>
 {% endblock %}
 
 {% block content %}
 <h2>Add a new bill</h2>
 
 <div class="container span-24 add-bill uniForm" style="width: 400px">
-    <form action="{{ url_for('add_bill', project_id=project.id) }}" method="post" class=uniForm">
+    <form action="{{ url_for('add_bill') }}" method="post" class=uniForm">
         {{ forms.add_bill(form) }}
     </form>
 </div>
diff --git a/budget/templates/add_member.html b/budget/templates/add_member.html
index 8d24aee..5739791 100644
--- a/budget/templates/add_member.html
+++ b/budget/templates/add_member.html
@@ -1,6 +1,6 @@
 {% extends "layout.html" %}
 {% block content %}
-    <form action="{{ url_for("add_member", project_id=project.id) }}" method="post">
+    <form action="{{ url_for("add_member") }}" method="post">
         {{ forms.add_member(form) }}
     </form>
 {% endblock %}
diff --git a/budget/templates/edit_bill.html b/budget/templates/edit_bill.html
index c78eb09..03a1a26 100644
--- a/budget/templates/edit_bill.html
+++ b/budget/templates/edit_bill.html
@@ -1,14 +1,14 @@
 {% extends "layout.html" %}
 
 {% block top_menu %}
-<a href="{{ url_for('list_bills', project_id=project.id) }}">Back to the list</a>
+<a href="{{ url_for('list_bills') }}">Back to the list</a>
 {% endblock %}
 
 {% block content %}
 <h2>Edit a bill</h2>
 
 <div class="container span-24 add-bill uniForm" style="width: 400px">
-    <form action="{{ url_for('edit_bill', project_id=project.id, bill_id=bill_id) }}" method="post" class=uniForm">
+    <form action="{{ url_for('edit_bill', bill_id=bill_id) }}" method="post" class=uniForm">
         {{ forms.add_bill(form) }}
     </form>
 </div>
diff --git a/budget/templates/invitation_mail b/budget/templates/invitation_mail
index 53991ed..83a7840 100644
--- a/budget/templates/invitation_mail
+++ b/budget/templates/invitation_mail
@@ -1,10 +1,10 @@
 Hi, 
 
-Someone using the email adress {{ email }} invited you to share your expenses for {{ project.name }} on our application.
+Someone using the email adress {{ g.project.contact_email }} invited you to share your expenses for {{ g.project.name }} on our application.
 
 It's as simple as saying what did you paid for, for who, and how much did it cost you, we are caring about the rest.
 
-You can access it here: {{ SITE_URL }}{{ url_for("list_bills", project_id=project.id) }}, the password is "{{ project.password }}".
+You can access it here: {{ SITE_URL }}{{ url_for("list_bills") }}, the password is "{{ g.project.password }}".
 
 Enjoy,
 Some weird guys
diff --git a/budget/templates/list_bills.html b/budget/templates/list_bills.html
index fe564e1..94b0f8f 100644
--- a/budget/templates/list_bills.html
+++ b/budget/templates/list_bills.html
@@ -42,24 +42,24 @@ $('.members li').hover(function(){
 {% block content %}
 <div id="leftmenu" class="span-6">
     <ul class="members">
-    {% set balance = project.get_balance() %}
-    {% for member in project.active_members %}
+    {% set balance = g.project.get_balance() %}
+    {% for member in g.project.active_members %}
     <li class="{{ loop.cycle("even", "odd") }}">
     <span class="balance {% if balance[member] > 0 %}positive{% elif balance[member] < 0 %}negative{% endif %}">{{ balance[member] }}</span>
     {{ member.name }}
-    <a class="remove" href="{{ url_for("remove_member", project_id=project.id, member_id=member.id) }}">delete</a></li>
+    <a class="remove" href="{{ url_for("remove_member", member_id=member.id) }}">delete</a></li>
     {% endfor %}
     </ul>
-    <form action="{{ url_for("add_member", project_id=project.id) }}" method="post">
+    <form action="{{ url_for("add_member") }}" method="post">
         {{ forms.add_member(member_form) }}
     </form>
 </div>
 <div id="content" class="uniForm span-18 last">
-    <a id="add_bill_button" class="awesome large green button fright" href="{{ url_for('add_bill', project_id=project.id) }}">Add a bill</a>
+    <a id="add_bill_button" class="awesome large green button fright" href="{{ url_for('add_bill') }}">Add a bill</a>
 
     <a id="hide_bill_form" class="awesome button fright" style="display: none;" href="#">Hide form</a>
 
-<form id="add_bill" action="{{ url_for('add_bill', project_id=project.id) }}" method="post" style="width: 400px; display: none">{{ forms.add_bill(bill_form) }}</form>
+<form id="add_bill" action="{{ url_for('add_bill') }}" method="post" style="width: 400px; display: none">{{ forms.add_bill(bill_form) }}</form>
 
     {% if bills.count() > 0 %}
     <table class="list_bills">
@@ -72,15 +72,15 @@ $('.members li').hover(function(){
             <td>{{ bill.what }}</td>
             <td>{% for ower in bill.owers %}{{ ower.name }} {% endfor %}</td>
             <td>{{ bill.amount }} ({{ bill.pay_each() }} each)</td>
-            <td><a href="{{ url_for("edit_bill", bill_id=bill.id, project_id=project.id) }}">edit</a>
-                <a href="{{ url_for("delete_bill", bill_id=bill.id, project_id=project.id) }}">delete</a></td>
+            <td><a href="{{ url_for("edit_bill", bill_id=bill.id) }}">edit</a>
+                <a href="{{ url_for("delete_bill", bill_id=bill.id) }}">delete</a></td>
     </tr>
     {% endfor %}
     </tbody>
     </table>
 
     {% else %}
-    <p>Nothing to list yet. You probably want to <a href="{{ url_for("add_bill", project_id=project.id) }}">add a bill</a> ?</p>
+    <p>Nothing to list yet. You probably want to <a href="{{ url_for("add_bill") }}">add a bill</a> ?</p>
     {% endif %}
 </div>
 {% endblock %}
diff --git a/budget/templates/send_invites.html b/budget/templates/send_invites.html
index f618803..fa46c81 100644
--- a/budget/templates/send_invites.html
+++ b/budget/templates/send_invites.html
@@ -3,12 +3,12 @@
 <h2>Invite people to join this project</h2>
 <p>Specify a (coma separated) list of email adresses you want to notify about the 
 creation of this budget management project and we will send them an email for you.</p>
-<p>If you prefer, you can <a href="{{ url_for("list_bills", project_id=project.id) }}">skip this step</a> and notify them yourself</p>
+<p>If you prefer, you can <a href="{{ url_for("list_bills") }}">skip this step</a> and notify them yourself</p>
 
 {% include "display_errors.html" %}
 <form method="post" accept-charset="utf-8">
     {{ form.hidden_tag() }}
     <p>{{ form.emails.label }}<br /> {{ form.emails }}</p>
-    <p>{{ form.submit }} <a href="{{ url_for("list_bills", project_id=project.id) }}">No, thanks</a></p>
+    <p>{{ form.submit }} <a href="{{ url_for("list_bills") }}">No, thanks</a></p>
 </form>
 {% endblock %}
diff --git a/budget/web.py b/budget/web.py
index e952109..14e058c 100644
--- a/budget/web.py
+++ b/budget/web.py
@@ -1,8 +1,8 @@
 from collections import defaultdict
 
-from flask import (Flask, session, request, redirect, url_for, render_template, 
-        flash)
+from flask import *
 from flaskext.mail import Mail, Message
+from werkzeug.routing import RequestRedirect
 
 # local modules
 from models import db, Project, Person, Bill
@@ -35,8 +35,6 @@ def authenticate(redirect_url=None):
     form = AuthenticationForm()
     
     project_id = form.id.data
-
-    redirect_url = redirect_url or url_for("list_bills", project_id=project_id)
     project = Project.query.get(project_id)
     create_project = False # We don't want to create the project by default
     if not project:
@@ -47,6 +45,7 @@ def authenticate(redirect_url=None):
     else:
         # if credentials are already in session, redirect
         if project_id in session and project.password == session[project_id]:
+            redirect_url = redirect_url or url_for("list_bills")
             return redirect(redirect_url)
 
         # else process the form
@@ -62,6 +61,8 @@ def authenticate(redirect_url=None):
                     session["projects"].insert(0, (project_id, project.name))
                     session[project_id] = form.password.data
                     session.update()
+                    setattr(g, 'project', project)
+                    redirect_url = redirect_url or url_for("list_bills")
                     return redirect(redirect_url)
 
     return render_template("authenticate.html", form=form, 
@@ -95,9 +96,32 @@ def exit():
     session.clear()
     return redirect(url_for("home"))
 
-@app.route("/<string:project_id>/invite", methods=["GET", "POST"])
-@requires_auth
-def invite(project):
+@app.url_defaults
+def add_project_id(endpoint, values):
+    if 'project_id' in values or not hasattr(g, 'project'):
+        return
+    if app.url_map.is_endpoint_expecting(endpoint, 'project_id'):
+        values['project_id'] = g.project.id
+
+@app.url_value_preprocessor
+def pull_project(endpoint, values):
+    if not values:
+        values = {}
+    project_id = values.pop('project_id', None)
+    if project_id:
+        project = Project.query.get(project_id)
+        if not project:
+            raise RequestRedirect(url_for("create_project"))
+        if project.id in session and session[project.id] == project.password:
+            # add project into kwargs and call the original function
+            g.project = project
+        else:
+            # redirect to authentication page
+            raise RequestRedirect(
+                    url_for("authenticate", redirect_url=request.url))
+
+@app.route("/<project_id>/invite", methods=["GET", "POST"])
+def invite():
 
     form = InviteForm()
 
@@ -105,51 +129,46 @@ def invite(project):
         if form.validate():
             # send the email
 
-            message_body = render_template("invitation_mail", 
-                    email=project.contact_email, project=project)
+            message_body = render_template("invitation_mail")
 
             message_title = "You have been invited to share your"\
-                    + " expenses for %s" % project.name
+                    + " expenses for %s" % g.project.name
             msg = Message(message_title, 
                 body=message_body, 
                 recipients=[email.strip() 
                     for email in form.emails.data.split(",")])
             mail.send(msg)
-            return redirect(url_for("list_bills", project_id=project.id))
+            return redirect(url_for("list_bills"))
 
-    return render_template("send_invites.html", form=form, project=project)
+    return render_template("send_invites.html", form=form)
 
-@app.route("/<string:project_id>/")
-@requires_auth
-def list_bills(project):
+@app.route("/<project_id>/")
+def list_bills():
     bills = Bill.query.join(Person, Project)\
         .filter(Bill.payer_id == Person.id)\
         .filter(Person.project_id == Project.id)\
-        .filter(Project.id == project.id)\
+        .filter(Project.id == g.project.id)\
         .order_by(Bill.date.desc())
     return render_template("list_bills.html", 
-            bills=bills, project=project, 
-            member_form=MemberForm(project),
-            bill_form=get_billform_for(project)
+            bills=bills, member_form=MemberForm(g.project),
+            bill_form=get_billform_for(g.project)
     )
 
-@app.route("/<string:project_id>/members/add", methods=["GET", "POST"])
-@requires_auth
-def add_member(project):
+@app.route("/<project_id>/members/add", methods=["GET", "POST"])
+def add_member():
     # FIXME manage form errors on the list_bills page
-    form = MemberForm(project)
+    form = MemberForm(g.project)
     if request.method == "POST":
         if form.validate():
-            db.session.add(Person(name=form.name.data, project=project))
+            db.session.add(Person(name=form.name.data, project=g.project))
             db.session.commit()
-            return redirect(url_for("list_bills", project_id=project.id))
-    return render_template("add_member.html", form=form, project=project)
+            return redirect(url_for("list_bills"))
+    return render_template("add_member.html", form=form)
 
-@app.route("/<string:project_id>/members/<int:member_id>/delete", methods=["GET", "POST"])
-@requires_auth
-def remove_member(project, member_id):
+@app.route("/<project_id>/members/<member_id>/delete", methods=["GET", "POST"])
+def remove_member(member_id):
     person = Person.query.get_or_404(member_id)
-    if person.project == project:
+    if person.project == g.project:
         if not person.has_bills():
             db.session.delete(person)
             db.session.commit()
@@ -158,12 +177,11 @@ def remove_member(project, member_id):
             person.activated = False
             db.session.commit()
             flash("User '%s' has been desactivated" % person.name)
-    return redirect(url_for("list_bills", project_id=project.id))
+    return redirect(url_for("list_bills"))
 
-@app.route("/<string:project_id>/add", methods=["GET", "POST"])
-@requires_auth
-def add_bill(project):
-    form = get_billform_for(project)
+@app.route("/<project_id>/add", methods=["GET", "POST"])
+def add_bill():
+    form = get_billform_for(g.project)
     if request.method == 'POST':
         if form.validate():
             bill = Bill()
@@ -171,47 +189,43 @@ def add_bill(project):
             db.session.commit()
 
             flash("The bill has been added")
-            return redirect(url_for('list_bills', project_id=project.id))
+            return redirect(url_for('list_bills'))
 
-    return render_template("add_bill.html", form=form, project=project)
+    return render_template("add_bill.html", form=form)
 
 
-@app.route("/<string:project_id>/delete/<int:bill_id>")
-@requires_auth
-def delete_bill(project, bill_id):
+@app.route("/<project_id>/delete/<int:bill_id>")
+def delete_bill(bill_id):
     bill = Bill.query.get_or_404(bill_id)
     db.session.delete(bill)
     db.session.commit()
     flash("The bill has been deleted")
 
-    return redirect(url_for('list_bills', project_id=project.id))
+    return redirect(url_for('list_bills'))
 
 
-@app.route("/<string:project_id>/edit/<int:bill_id>", methods=["GET", "POST"])
-@requires_auth
-def edit_bill(project, bill_id):
+@app.route("/<project_id>/edit/<int:bill_id>", methods=["GET", "POST"])
+def edit_bill(bill_id):
     bill = Bill.query.get_or_404(bill_id)
-    form = get_billform_for(project, set_default=False)
+    form = get_billform_for(g.project, set_default=False)
     if request.method == 'POST' and form.validate():
         form.save(bill)
         db.session.commit()
 
         flash("The bill has been modified")
-        return redirect(url_for('list_bills', project_id=project.id))
+        return redirect(url_for('list_bills'))
 
     form.fill(bill)
-    return render_template("edit_bill.html", form=form, project=project, bill_id=bill_id)
+    return render_template("edit_bill.html", form=form, bill_id=bill_id)
 
-@app.route("/<string:project_id>/compute")
-@requires_auth
-def compute_bills(project):
+@app.route("/<project_id>/compute")
+def compute_bills():
     """Compute the sum each one have to pay to each other and display it"""
-    return render_template("compute_bills.html", project=project)
+    return render_template("compute_bills.html")
 
 
-@app.route("/<string:project_id>/reset")
-@requires_auth
-def reset_bills(project):
+@app.route("/<project_id>/reset")
+def reset_bills():
     """Reset the list of bills"""
     # FIXME replace with the archive feature
     # get all the bills which are not processed