diff --git a/Makefile.am b/Makefile.am
index bad9ce7..d4916fb 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -7,6 +7,7 @@ pkgmoduledir=$(datarootdir)/guile/site/2.0/$(PACKAGE)
 dist_pkgmodule_DATA = \
   src/cuirass/base.scm \
   src/cuirass/database.scm \
+  src/cuirass/http.scm \
   src/cuirass/ui.scm \
   src/cuirass/utils.scm
 
@@ -34,6 +35,7 @@ TESTS = \
   tests/base.scm \
 ## tests/basic.sh # takes too long to execute
   tests/database.scm \
+  tests/http.scm \
   tests/ui.scm \
   tests/utils.scm
 
diff --git a/configure.ac b/configure.ac
index 660a117..ad6f4be 100644
--- a/configure.ac
+++ b/configure.ac
@@ -23,6 +23,7 @@ AS_IF([test -z "$ac_cv_path_GUILD"],
   [AC_MSG_ERROR(['guild' program cannot be found.])])
 
 GUILE_MODULE_REQUIRED([guix])
+GUILE_MODULE_REQUIRED([json])
 GUILE_MODULE_REQUIRED([sqlite3])
 
 AC_CONFIG_FILES([Makefile
diff --git a/src/cuirass/http.scm b/src/cuirass/http.scm
new file mode 100644
index 0000000..459dba9
--- /dev/null
+++ b/src/cuirass/http.scm
@@ -0,0 +1,75 @@
+;;; http.scm -- HTTP API
+;;; Copyright © 2016 Mathieu Lirzin <mthl@gnu.org>
+;;;
+;;; This file is part of Cuirass.
+;;;
+;;; Cuirass is free software: you can redistribute it and/or modify
+;;; it under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; Cuirass is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with Cuirass.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (cuirass http)
+  #:use-module (cuirass database)
+  #:use-module (cuirass utils)
+  #:use-module (ice-9 hash-table)
+  #:use-module (ice-9 match)
+  #:use-module (json)
+  #:use-module (web request)
+  #:use-module (web response)
+  #:use-module (web server)
+  #:use-module (web uri)
+  #:export (spec->json-string
+            run-cuirass-server))
+
+;;;
+;;; JSON format.
+;;;
+
+(define (object->json-scm obj)
+  "Prepare OBJ for JSON usage."
+  (cond ((string? obj)  obj)
+        ((number? obj)  obj)
+        ((boolean? obj) obj)
+        ((null? obj)    obj)
+        ((symbol? obj)  (symbol->string obj))
+        ((keyword? obj) (object->json-scm (keyword->symbol obj)))
+        ((alist? obj)   (alist->hash-table (map object->json-scm obj)))
+        ((pair? obj)    (cons (object->json-scm (car obj))
+                              (object->json-scm (cdr obj))))
+        (else           (object->string obj))))
+
+(define* (spec->json-string spec #:key pretty)
+  "Return SPEC as a JSON object."
+  (scm->json-string (object->json-scm spec) #:pretty pretty))
+
+
+;;;
+;;; Web server.
+;;;
+
+(define (request-path-components request)
+  (split-and-decode-uri-path (uri-path (request-uri request))))
+
+(define (not-found request)
+  (values (build-response #:code 404)
+          (string-append "Resource not found: "
+                         (uri->string (request-uri request)))))
+
+(define (url-handler request body)
+  (match (request-path-components request)
+    (((or "jobsets" "specifications") . rest)
+     (values '((content-type . (application/json)))
+             (with-database db
+               (spec->json-string (car (db-get-specifications db))))))
+    (_ (not-found request))))
+
+(define (run-cuirass-server)
+  (run-server url-handler))
diff --git a/tests/http.scm b/tests/http.scm
new file mode 100644
index 0000000..09601a9
--- /dev/null
+++ b/tests/http.scm
@@ -0,0 +1,33 @@
+;;; http.scm -- tests for (cuirass http) module
+;;; Copyright © 2016 Mathieu Lirzin <mthl@gnu.org>
+;;;
+;;; This file is part of Cuirass.
+;;;
+;;; Cuirass is free software: you can redistribute it and/or modify
+;;; it under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; Cuirass is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with Cuirass.  If not, see <http://www.gnu.org/licenses/>.
+
+(use-modules (cuirass http)
+             (srfi srfi-64))
+
+(test-begin "http")
+
+(test-equal "spec->json-string"
+  "{\"boolean\" : false,\"string\" : \"guix\",\"alist\" : {\"subset\" : \"hello\"},\"list\" : [1, \"2\", \"three\"],\"symbol\" : \"hydra-jobs\",\"number\" : 1}"
+  (spec->json-string   '((#:number . 1)
+                         (string . "guix")
+                         ("symbol" . hydra-jobs)
+                         (#:alist (subset . "hello"))
+                         (list 1 "2" #:three)
+                         ("boolean" . #f))))
+
+(test-end)