diff --git a/project.clj b/project.clj
index 595fcd6..5b79ce4 100644
--- a/project.clj
+++ b/project.clj
@@ -5,6 +5,7 @@
 
   :dependencies [;;clojure core
                  [org.clojure/clojure "1.10.1"]
+                 [org.clojure/tools.logging "0.4.1"]
 
                  ;; static site
                  [compojure "1.6.1"]
diff --git a/src/wanijo/attribute/domain.clj b/src/wanijo/attribute/domain.clj
index 1a21dac..10cd386 100644
--- a/src/wanijo/attribute/domain.clj
+++ b/src/wanijo/attribute/domain.clj
@@ -14,6 +14,11 @@
 (spec/def ::created-at
   (spec/and string? ::neo4j/date-str))
 
+(spec/def ::attribute
+  (spec/keys ::req-un [::name
+                       ::type
+                       ::created-at]))
+
 (neo4j/defquery
   findy-by-schema
   "MATCH (a:attribute)-->(s:schema)
diff --git a/src/wanijo/handler.clj b/src/wanijo/handler.clj
index 2af6139..b50ac47 100644
--- a/src/wanijo/handler.clj
+++ b/src/wanijo/handler.clj
@@ -7,6 +7,7 @@
             [ring.util.response :as rur]
             [ring.middleware.session.cookie :as session-cookie]
             [ring.middleware.json :as ring-json]
+            [clojure.spec.alpha :as spec]
             [wanijo.home.routes :as home-routes]
             [wanijo.schema
              [routes :as schema-routes]
@@ -43,8 +44,14 @@
       schema-middleware/wrap-user-schemas
       (wrap-defaults site-defaults)))
 
+(defn wrap-spec-asserts [handler]
+  (fn [req]
+    (spec/check-asserts true)
+    (handler req)))
+
 (def app
   (-> app-routes
+      wrap-spec-asserts
       devmode/wrap-devmode
       schema-middleware/wrap-user-schemas
       ring-json/wrap-json-response
diff --git a/src/wanijo/instance/domain.clj b/src/wanijo/instance/domain.clj
index 95b9e09..d8bf6a6 100644
--- a/src/wanijo/instance/domain.clj
+++ b/src/wanijo/instance/domain.clj
@@ -1,11 +1,14 @@
 (ns wanijo.instance.domain
   (:require [clojure.spec.alpha :as spec]
             [wanijo.framework.neo4j :as neo4j]
-            [clojure.pprint :as pprint]))
+            [wanijo.schema.domain :as domain-schema]
+            [wanijo.attribute.domain :as domain-attr]))
 
 (spec/def ::created-at ::neo4j/date-str)
+(spec/def ::created_at ::neo4j/date-str)
 (spec/def ::updated-at ::neo4j/date-str)
-(spec/def ::name (spec/and (complement empty?) string?))
+(spec/def ::updated_at ::neo4j/date-str)
+(spec/def ::name string?)
 (spec/def ::value
   (spec/or :string string?
            :bool boolean?
@@ -13,6 +16,38 @@
            :number number?))
 (spec/def ::instance_uuid ::neo4j/uuid)
 (spec/def ::attribute_uuid ::neo4j/uuid)
+(spec/def ::instance
+  (spec/keys :req-un [::neo4j/uuid
+                      ::created_at
+                      ::updated_at
+                      ::name]))
+(spec/def ::properties
+  (spec/coll-of
+   (spec/keys :req-un [::neo4j/uuid
+                       ::created_at
+                       ::updated_at
+                       ::domain-attr/attribute])))
+(spec/def ::link
+  (spec/keys :req-un [::neo4j/uuid
+                      ::created_at
+                      ::name]))
+(spec/def ::target ::instance)
+(spec/def ::source ::instance)
+(spec/def ::links-out
+  (spec/coll-of
+   (spec/keys :req-un [::link
+                       ::target
+                       ::domain-schema/schema])))
+(spec/def ::links-in
+  (spec/coll-of
+   (spec/keys :req-un [::link
+                       ::source
+                       ::domain-schema/schema])))
+(spec/def ::tags
+  (spec/coll-of
+   (spec/keys :req-un [::neo4j/uuid
+                       ::name
+                       ::created-at])))
 
 (neo4j/defquery findy-by-schema
   "MATCH (i:instance)-[:of]->(s:schema)
@@ -70,7 +105,13 @@
          -[:of]->(s:schema)
    RETURN i, s")
 
+(spec/def ::instance-with-schema
+  (spec/and ::instance
+            (spec/keys :req-un
+                       [::domain-schema/schema])))
+
 (defn find-by-uuid! [uuid]
+  {:post [(spec/assert ::instance-with-schema %)]}
   (->> (neo4j/exec-query! find-by-uuid
                           {:uuid uuid})
        (map #(assoc (:i %)
@@ -96,7 +137,6 @@
   "MATCH (i:instance {uuid:{uuid}})
      SET i.name = {name},
          i.updated_at = {updated_at}")
-
 (neo4j/defquery edit-property
   "MATCH (i:instance {uuid:{instance_uuid}}),
          (a:attribute {uuid:{attribute_uuid}})
@@ -107,7 +147,6 @@
                  p.value = {value}
    ON MATCH SET p.updated_at = {now},
                 p.value = {value}")
-
 (spec/def ::now ::neo4j/date-str)
 (spec/def ::prop-tuple-values
   (spec/keys :req-un [::neo4j/uuid
@@ -118,7 +157,6 @@
 (spec/def ::prop-tuple
   (spec/coll-of
    (spec/tuple fn? ::prop-tuple-values)))
-
 (defn instance->prop-tuples [instance]
   {:post [(spec/assert ::prop-tuple %)]}
   (map (fn [prop]
@@ -133,7 +171,6 @@
              :instance_uuid (:uuid instance)
              :attribute_uuid (-> prop :attribute :uuid)}]))
        (:properties instance)))
-
 (defn edit! [instance]
   (let [prop-tuples (instance->prop-tuples instance)]
     (apply neo4j/exec-queries!
@@ -151,7 +188,6 @@
          (p:property)-[pc:of]->(i),
          (p)-[pac:of]->(a:attribute)
    DELETE pac, pc, cb, ic, p, i")
-
 (defn delete! [uuid]
   (neo4j/exec-query! delete {:uuid uuid}))
 
@@ -163,7 +199,6 @@
       SET l.created_at = {created_at},
           l.name = {name}
    CREATE (i)<-[:link_from]-(l)-[:link_to]->(t)")
-
 (defn create-link! [link]
   (let [tuples (map (fn [target-uuid]
                       [create-link
@@ -183,8 +218,8 @@
          (t)-[:of]->(s:schema)
    RETURN i, l, t, s
    ORDER BY s.name, t.name, t.created_at")
-
 (defn outgoing-links! [uuid]
+  {:post [(spec/assert ::links-out %)]}
   (map (fn [row]
          {:link (:l row)
           :target (:t row)
@@ -199,8 +234,8 @@
          (source)-[:of]->(schema:schema)
    RETURN i, l, source, schema
    ORDER BY schema.name, source.name, source.created_at")
-
 (defn incoming-links! [uuid]
+  {:post [(spec/assert ::links-in %)]}
   (map (fn [row]
          {:link (:l row)
           :source (:source row)
@@ -212,7 +247,6 @@
   "MATCH (l:link {uuid:{uuid}}),
          (l)-[r]-()
    DELETE r, l")
-
 (defn delete-link! [uuid]
   (neo4j/exec-query! delete-link
                      {:uuid uuid}))
@@ -221,12 +255,23 @@
   "MATCH (i:instance {uuid:{uuid}})-[:has]->(t:tag)
    RETURN t
    ORDER BY t.name")
-
 (defn tags! [uuid]
+  {:post [(spec/assert ::tags %)]}
   (neo4j/exec-query! tags
                      {:uuid uuid}))
 
+(spec/def ::full-instance
+  (spec/and ::instance-with-schema
+            (spec/keys ::req-un [::neo4j/uuid
+                                 ::created-at
+                                 ::updated-at
+                                 ::name
+                                 ::properties
+                                 ::links-out
+                                 ::links-in
+                                 ::tags])))
 (defn full-instance-by-uuid! [uuid]
+  {:post [(spec/assert ::full-instance %)]}
   (assoc (find-by-uuid! uuid)
          :properties
          (find-properties! uuid)
@@ -241,7 +286,6 @@
   "MATCH (u:user {uuid:{user_uuid}}),
          (i:instance {uuid:{uuid}})
    RETURN EXISTS((i)-[:starred_by]->(u)) AS starred")
-
 (defn is-starred! [uuid user-uuid]
   (-> (neo4j/exec-query! is-starred
                          {:user_uuid user-uuid
@@ -255,7 +299,6 @@
    MERGE (i)-[s:starred_by]->(u)
    ON CREATE
    SET s.created_at = {now}")
-
 (defn mark-starred! [uuid user-uuid]
   (neo4j/exec-query! mark-starred
                      {:uuid uuid
@@ -267,7 +310,6 @@
          -[s:starred_by]->
          (:user {uuid:{user_uuid}})
    DELETE s")
-
 (defn remove-starred! [uuid user-uuid]
   (neo4j/exec-query! remove-starred
                      {:uuid uuid
@@ -279,7 +321,6 @@
          (i:instance)
    RETURN i, s
    ORDER BY s.created_at DESC")
-
 (defn starred-by-user! [user-uuid]
   (map #(assoc (:i %)
                :starred_at (-> % :s :created_at))
diff --git a/src/wanijo/main.clj b/src/wanijo/main.clj
index e3ec709..1c3e5d3 100644
--- a/src/wanijo/main.clj
+++ b/src/wanijo/main.clj
@@ -1,11 +1,8 @@
 (ns wanijo.main
   (:require [ring.adapter.jetty :refer [run-jetty]]
-            [clojure.spec.alpha :as spec]
-            [wanijo.handler :as wanijo])
+            [wanijo.handler :as wanijo-handler])
   (:gen-class))
 
-(spec/check-asserts true)
-
 (defonce server (atom nil))
 
 (defn start-server!
@@ -14,7 +11,7 @@
       :or {port 3080
            join? true}}]
   (reset! server
-          (run-jetty wanijo/standalone-app
+          (run-jetty wanijo-handler/standalone-app
                      {:port port
                       :join? join?})))
 
diff --git a/src/wanijo/schema/domain.clj b/src/wanijo/schema/domain.clj
index 00981d3..4944c77 100644
--- a/src/wanijo/schema/domain.clj
+++ b/src/wanijo/schema/domain.clj
@@ -4,17 +4,18 @@
 
 (spec/def ::name
   (spec/and string? not-empty))
-
 (spec/def ::created-at
   (spec/and string? ::neo4j/date-str))
-
 (spec/def ::assigned-to
   (spec/or :public empty?
            :assigned-single ::neo4j/uuid
            :assigned (spec/coll-of ::neo4j/uuid)))
+(spec/def ::schema
+  (spec/keys ::req-un [::name
+                       ::created-at
+                       ::neo4j/uuid]))
 
-(neo4j/defquery
-  all-created-by
+(neo4j/defquery all-created-by
   "MATCH (s:schema)-[:created_by]->(u:user)
    WHERE u.uuid = {uuid}
    RETURN s
@@ -26,8 +27,7 @@
         all-created-by
         {:uuid user-uuid})))
 
-(neo4j/defquery
-  all
+(neo4j/defquery all
   "MATCH (s:schema)
    RETURN s
    ORDER BY s.name")
@@ -36,8 +36,7 @@
   (map :s
        (neo4j/exec-query! all {})))
 
-(neo4j/defquery
-  create-new
+(neo4j/defquery create-new
   "MATCH (u:user)
    WHERE u.uuid = {u_uuid}
    CREATE (s:schema)-[:created_by]->(u)
@@ -57,8 +56,7 @@
    first
    :uuid))
 
-(neo4j/defquery
-  find-by-uuid
+(neo4j/defquery find-by-uuid
   "MATCH (s:schema)
    WHERE s.uuid = {uuid}
    RETURN s")
@@ -71,8 +69,7 @@
    first
    :s))
 
-(neo4j/defquery
-  schema-creator
+(neo4j/defquery schema-creator
   "MATCH (s:schema)-->(u:user)
    WHERE s.uuid = {uuid}
    RETURN u.uuid as uuid")
@@ -85,8 +82,7 @@
    first
    :uuid))
 
-(neo4j/defquery
-  schema-permissions
+(neo4j/defquery schema-permissions
   "MATCH (s:schema {uuid:{schema_uuid}})
    RETURN
      EXISTS((:user {uuid:{user_uuid}})
@@ -111,8 +107,7 @@
 (defn has-user-read-permissions? [schema-uuid user-uuid]
   (has-user-permission? "read" schema-uuid user-uuid))
 
-(neo4j/defquery
-  accessible-schemas
+(neo4j/defquery accessible-schemas
   "MATCH (s:schema),
          (u:user {uuid:{user_uuid}})
    WHERE EXISTS((u)-[:permission {type:'read'}]->(s))
@@ -125,8 +120,7 @@
        (neo4j/exec-query! accessible-schemas
                           {:user_uuid user-uuid})))
 
-(neo4j/defquery
-  delete
+(neo4j/defquery delete
   "MATCH (s:schema)
    WHERE s.uuid = {uuid}
    OPTIONAL MATCH (s)--(a:attribute)
@@ -140,8 +134,7 @@
    delete
    {:uuid uuid}))
 
-(neo4j/defquery
-  edit
+(neo4j/defquery edit
   "MATCH (s:schema)
    WHERE s.uuid = {uuid}
      SET s.name = {name}")
@@ -151,8 +144,7 @@
    edit
    schema))
 
-(neo4j/defquery
-  assigned-users
+(neo4j/defquery assigned-users
   "MATCH (s:schema)-[p:permission]-(u:user)
    WHERE s.uuid = {uuid}
    RETURN u, p
@@ -163,8 +155,7 @@
    assigned-users
    {:uuid uuid}))
 
-(neo4j/defquery
-  assigned-schemas
+(neo4j/defquery assigned-schemas
   "MATCH (s1:schema)-[p:permission]-(s2:schema)
    WHERE s1.uuid = {uuid}
    RETURN s2
@@ -189,15 +180,13 @@
            :assigned-write-users (:write users)
            :assigned-schemas schemas)))
 
-(neo4j/defquery
-  remove-assignments
+(neo4j/defquery remove-assignments
   "MATCH (s:schema)-[c:permission]-(:user)
    WHERE s.uuid = {uuid}
      AND c.type = {permtype}
    DELETE c")
 
-(neo4j/defquery
-  create-assignments
+(neo4j/defquery create-assignments
   "MATCH (s:schema), (u:user)
    WHERE s.uuid = {uuid}
      AND u.uuid IN {users}
@@ -213,14 +202,12 @@
      :users users
      :permtype permission}]))
 
-(neo4j/defquery
-  remove-schema-assignments
+(neo4j/defquery remove-schema-assignments
   "MATCH (s1:schema)-[p:permission]-(s2:schema)
    WHERE s1.uuid = {uuid}
    DELETE p")
 
-(neo4j/defquery
-  create-schema-assignments
+(neo4j/defquery create-schema-assignments
   "MATCH (s1:schema), (s2:schema)
    WHERE s1.uuid = {uuid}
      AND s2.uuid IN {schemas}