diff --git a/docs/index.rst b/docs/index.rst
index eeee06e..9e35a07 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -20,6 +20,7 @@ User's Guide
    usage
    configuration
    twtxtfile
+   registry
 
 
 API Reference
diff --git a/docs/registry.rst b/docs/registry.rst
new file mode 100644
index 0000000..8149bcf
--- /dev/null
+++ b/docs/registry.rst
@@ -0,0 +1,119 @@
+.. registry:
+
+Registry
+========
+
+Since twtxt is decentralized by design, features like the timeline are limited to the twtxt users followed by you. To
+provide a global search for mentions or hash tags, the client will be able to query so called registries.
+
+A reference implementation is available at `twtxt-registry (source)`_ in nodejs and
+a demo instance is running at `twtxt-registry (demo)`_.
+
+The client will support multiple registries at the same time, to circumvent possible single point of failures. The
+registries should sync each others user list by using the `users` endpoint.
+
+Format specification
+----------------------------
+
+**Writing to the registry**
+
+The responses return proper status code (200 OK) and the description of the status code or a
+detailed error message.
+
+**Reading from the registry**
+
+The responses contain one status per line, each of which is equipped with reference to the
+poster followed by a TAB and an ISO 8601 date/time string followed by a TAB character (\\t) to separate it from the actual
+text.
+
+**General rules**
+
+1. All lists are sorted by timestamp in descending order (most recent one first)
+2. All lists support the `page` query parameter to get the next page of the result set.
+3. The response must be encoded with UTF-8 and must use LF (\\n) as line separators.
+
+Api Endpoints
+-------------
+
+The url to the registry consists of its basepath (e.g. `https://registry.twtxt.org/api/`). The format (e.g. `plain`) is
+appended, because we might support json or xml format sooner or later.
+
+The following parameters:
+
+* basePath: `https://registry.twtxt.org/api/`
+* format: `plain`
+* endpoint: `tags/twtxt`
+
+will call this url: `https://registry.twtxt.org/api/plain/tags/twtxt`.
+
+Add new User
+------------
+
+Add a new Twtxt User to the Registry (Status Code is 200):
+
+.. code::
+
+	$ curl -X POST https://registry.twtxt.org/api/plain/users?url=https://example.org/twtxt.txt&nickname=example
+	OK
+
+If it fails to add a new Twtxt User to the Registry (Status Code is 400):
+
+.. code::
+
+	$ curl -X POST https://registry.twtxt.org/api/plain/users?url=https://example.org/twtxt.txt
+	Bad Request: `nickname` is missing
+
+See latest tweets in the Registry (e.g. <https://registry.twtxt.org/api/plain/tweets>):
+
+.. code::
+
+	$ curl https://registry.twtxt.org/api/plain/tweets
+	@<example https://example.org/twtxt.txt>	2016-02-06T21:32:02.000Z	@erlehmann is messing with timestamps in @buckket #twtxt :)
+	@<example https://example.org/twtxt.txt>	2016-02-06T12:14:18.000Z	Simple nodejs script to convert your twitter timeline to twtxt: https://t.co/txnWsC5jvA ( find my #twtxt at https://t.co/uN1KDXwJ8B )
+
+Search for tweets
+-----------------
+
+To query for tweets, which contain a specific word, use the tweets endpoint and the q query parameter.
+
+.. code::
+
+	$ curl https://registry.twtxt.org/api/plain/tweets?q=twtxt
+	@<buckket https://buckket.org/twtxt.txt>	2016-02-09T12:42:26.000Z	Do we need an IRC channel for twtxt?
+	@<buckket https://buckket.org/twtxt.txt>	2016-02-09T12:42:12.000Z	Good Morning, twtxt-world!
+
+Query for mentions
+------------------
+
+To query for all tweets, which mention a specific user, use the mentions endpoint and the url query parameter.
+
+.. code::
+
+	$ curl https://registry.twtxt.org/api/plain/mentions?url=https://buckket.org/twtxt.txt
+	@<example https://example.org/twtxt.txt>	2016-02-09T12:57:59.000Z	@<buckket https://buckket.org/twtxt.txt> something like https://gitter.im/ or a freenode channel?
+	@<example https://example.org/twtxt.txt>	2016-02-08T22:51:47.000Z	@<buckket https://buckket.org/twtxt.txt> looks nice ;)
+
+Query for tags
+--------------
+
+To query for all tweets, which contain a specific tag like `#twtxt`, use the tags endpoint and prepend the tag.
+
+.. code::
+
+	$ curl https://registry.twtxt.org/api/plain/tags/twtxt
+	@<example https://example.org/twtxt.txt>	2016-02-06T21:32:02.000Z	@erlehmann is messing with timestamps in @buckket #twtxt :)
+	@<example https://example.org/twtxt.txt>	2016-02-06T12:14:18.000Z	Simple nodejs script to convert your twitter timeline to twtxt: https://t.co/txnWsC5jvA ( find my #twtxt at https://t.co/uN1KDXwJ8B )
+
+Query for users
+---------------
+
+To query for a user list, use the users endpoint and refine with the q query parameter.
+
+.. code::
+
+	$ curl https://registry.twtxt.org/api/plain/users?q=example
+	<@example https://example.org/twtxt.txt>	2016-02-09T12:42:26.000Z	example
+	<@example https://example.org/42.twtxt.txt>	2016-02-10T13:20:10.000Z	example42
+
+.. _twtxt-registry (source): https://github.com/DracoBlue/twtxt-registry
+.. _twtxt-registry (demo): https://registry.twtxt.org