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.. notice for github users


Certbot (previously, the Let's Encrypt client) is BETA SOFTWARE. It
contains plenty of bugs and rough edges, and should be tested thoroughly in
staging environments before use on production systems.

For more information regarding the status of the project, please see Be sure to checkout the
Frequently Asked Questions (FAQ) <>_.

About Certbot

Certbot is a fully-featured, extensible client for the Let's
Encrypt CA (or any other CA that speaks the ACME <>_
protocol) that can automate the tasks of obtaining certificates and
configuring webservers to use them. This client runs on Unix-based operating

Until May 2016, Certbot was named simply letsencrypt or letsencrypt-auto,
depending on install method. Instructions on the Internet, and some pieces of the
software, may still refer to this older name.


If you'd like to contribute to this project please read Developer Guide <>_.

.. _installation:


If certbot (or letsencrypt) is packaged for your Unix OS (visit
certbot.eff.org_ to find out), you can install it
from there, and run it by typing certbot (or letsencrypt). Because
not all operating systems have packages yet, we provide a temporary solution
via the certbot-auto wrapper script, which obtains some dependencies from
your OS and puts others in a python virtual environment::

user@webserver:~$ wget
user@webserver:~$ chmod a+x ./certbot-auto
user@webserver:~$ ./certbot-auto --help

.. hint:: The certbot-auto download is protected by HTTPS, which is pretty good, but if you'd like to
double check the integrity of the certbot-auto script, you can use these steps for verification before running it::

        user@server:~$ wget -N
        user@server:~$ gpg2 --recv-key A2CFB51FA275A7286234E7B24D17C995CD9775F2
        user@server:~$ gpg2 --trusted-key 4D17C995CD9775F2 --verify certbot-auto.asc certbot-auto

And for full command line help, you can type::

./certbot-auto --help all

certbot-auto updates to the latest client release automatically. And
since certbot-auto is a wrapper to certbot, it accepts exactly
the same command line flags and arguments. More details about this script and
other installation methods can be found in the User Guide <>_.

How to run the client

In many cases, you can just run certbot-auto or certbot, and the
client will guide you through the process of obtaining and installing certs

You can also tell it exactly what you want it to do from the command line.
For instance, if you want to obtain a cert for,, and, using the Apache plugin to both
obtain and install the certs, you could do this::

./certbot-auto --apache -d -d -d

(The first time you run the command, it will make an account, and ask for an
email and agreement to the Let's Encrypt Subscriber Agreement; you can
automate those with --email and --agree-tos)

If you want to use a webserver that doesn't have full plugin support yet, you
can still use "standalone" or "webroot" plugins to obtain a certificate::

./certbot-auto certonly --standalone --email -d -d -d

Understanding the client in more depth

To understand what the client is doing in detail, it's important to
understand the way it uses plugins. Please see the explanation of plugins <>_ in
the User Guide.



Software project:

Notes for developers:

Main Website:

IRC Channel: #letsencrypt on Freenode_ or #certbot on OFTC_


ACME spec:

ACME working area in github:

Mailing list: client-dev_ (to subscribe without a Google account, send an
email to

|build-status| |coverage| |docs| |container|

.. |build-status| image::
:alt: Travis CI status

.. |coverage| image::
:alt: Coverage status

.. |docs| image::
:alt: Documentation status

.. |container| image::
:alt: Docker Repository on

.. _installation instructions:

.. _watch demo video:

System Requirements

The Let's Encrypt Client presently only runs on Unix-ish OSes that include
Python 2.6 or 2.7; Python 3.x support will hopefully be added in the future. The
client requires root access in order to write to /etc/letsencrypt,
/var/log/letsencrypt, /var/lib/letsencrypt; to bind to ports 80 and 443
(if you use the standalone plugin) and to read and modify webserver
configurations (if you use the apache or nginx plugins). If none of
these apply to you, it is theoretically possible to run without root privileges,
but for most users who want to avoid running an ACME client as root, either
letsencrypt-nosudo <>_ or
simp_le <>_ are more appropriate choices.

The Apache plugin currently requires a Debian-based OS with augeas version
1.0; this includes Ubuntu 12.04+ and Debian 7+.

Current Features

  • Supports multiple web servers:

    • apache/2.x (working on Debian 8+ and Ubuntu 12.04+)
    • standalone (runs its own simple webserver to prove you control a domain)
    • webroot (adds files to webroot directories in order to prove control of
      domains and obtain certs)
    • nginx/0.8.48+ (highly experimental, not included in certbot-auto)
  • The private key is generated locally on your system.

  • Can talk to the Let's Encrypt CA or optionally to other ACME
    compliant services.
  • Can get domain-validated (DV) certificates.
  • Can revoke certificates.
  • Adjustable RSA key bit-length (2048 (default), 4096, ...).
  • Can optionally install a http -> https redirect, so your site effectively
    runs https only (Apache only)
  • Fully automated.
  • Configuration changes are logged and can be reverted.
  • Supports ncurses and text (-t) UI, or can be driven entirely from the
    command line.
  • Free and Open Source Software, made with Python.

.. _Freenode:
.. _OFTC:
.. _client-dev:!forum/client-dev

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