diff --git a/planetstack/core/xoslib/static/css/xosAdminSite.css b/planetstack/core/xoslib/static/css/xosAdminSite.css
index f09bbcf..ad9eb47 100644
--- a/planetstack/core/xoslib/static/css/xosAdminSite.css
+++ b/planetstack/core/xoslib/static/css/xosAdminSite.css
@@ -66,6 +66,11 @@
     text-decoration:none;
 }
 
+.help-inline.error {
+    color: red;
+    font-weight: bold;
+}
+
 /* these are for the inline list and detail titles */
 
 .xos-list-title {
diff --git a/planetstack/core/xoslib/static/js/xoslib/xos-backbone.js b/planetstack/core/xoslib/static/js/xoslib/xos-backbone.js
index bbf13a4..a04fd8f 100644
--- a/planetstack/core/xoslib/static/js/xoslib/xos-backbone.js
+++ b/planetstack/core/xoslib/static/js/xoslib/xos-backbone.js
@@ -68,6 +68,21 @@
                     }
                 }
                 return res;
+            },
+
+            validate: function(attrs, options) {
+                errors = {};
+                _.each(this.validators, function(validatorList, fieldName) {
+                    _.each(validatorList, function(validator) {
+                        if (fieldName in attrs) {
+                            validatorResult = validateField(validator, attrs[fieldName])
+                            if (validatorResult != true) {
+                                errors[fieldName] = validatorResult;
+                            }
+                        }
+                    });
+                });
+                return errors;
             }
     });
 
@@ -287,6 +302,10 @@
             modelAttrs["defaults"] = xosdefaults[modelName];
         }
 
+        if (xosvalidators && xosvalidators[modelName]) {
+            modelAttrs["validators"] = xosvalidators[modelName];
+        }
+
         lib[modelName] = XOSModel.extend(modelAttrs);
 
         collectionAttrs["model"] = lib[modelName];
diff --git a/planetstack/core/xoslib/static/js/xoslib/xos-util.js b/planetstack/core/xoslib/static/js/xoslib/xos-util.js
index 79ce0f8..bebc44a 100644
--- a/planetstack/core/xoslib/static/js/xoslib/xos-util.js
+++ b/planetstack/core/xoslib/static/js/xoslib/xos-util.js
@@ -21,3 +21,19 @@
         wrapper.style.height = height + "px";
     }
 }
+
+function validateField(validatorName, value) {
+    switch (validatorName) {
+        case "notBlank":
+            if ((value==undefined) || (value=="")) {
+                return "can not be blank";
+            }
+            break;
+        case "isUrl":
+            if (! /^(https?|ftp):\/\/(((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:)*@)?(((\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.(\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5]))|((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?)(:\d*)?)(\/((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)+(\/(([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)*)*)?)?(\?((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)|[\uE000-\uF8FF]|\/|\?)*)?(\#((([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(%[\da-f]{2})|[!\$&'\(\)\*\+,;=]|:|@)|\/|\?)*)?$/i.test(value)) {
+                return "must be a valid url";
+            }
+            break;
+    }
+    return true;
+}
diff --git a/planetstack/core/xoslib/static/js/xoslib/xosHelper.js b/planetstack/core/xoslib/static/js/xoslib/xosHelper.js
index 8fa27a6..30835c7 100644
--- a/planetstack/core/xoslib/static/js/xoslib/xosHelper.js
+++ b/planetstack/core/xoslib/static/js/xoslib/xosHelper.js
@@ -264,10 +264,22 @@
 
             save: function() {
                 this.app.hideError();
-                var infoMsgId = this.app.showInformational( {what: "save " + model.modelName + " " + model.attributes.humanReadableName, status: "", statusText: "in progress..."} );
                 var data = Backbone.Syphon.serialize(this);
                 var that = this;
                 var isNew = !this.model.id;
+
+                /* although model.validate() is called automatically by
+                   model.save, we call it ourselves, so we can throw up our
+                   validation error before creating the infoMsg in the log
+                */
+                errors =  this.model.validate(data);
+                if (errors) {
+                    this.onFormDataInvalid(errors);
+                    return;
+                }
+
+                var infoMsgId = this.app.showInformational( {what: "save " + model.modelName + " " + model.attributes.humanReadableName, status: "", statusText: "in progress..."} );
+
                 this.model.save(data, {error: function(model, result, xhr) { that.saveError(model,result,xhr,infoMsgId);},
                                        success: function(model, result, xhr) { that.saveSuccess(model,result,xhr,infoMsgId);}});
                 if (isNew) {
@@ -356,6 +368,19 @@
                     this.tabClick('#xos-nav-detail', 'detail');
               },
 
+            onFormDataInvalid: function(errors) {
+                var self=this;
+                var markErrors = function(value, key) {
+                    console.log("name='" + key + "'");
+                    var $inputElement = self.$el.find("[name='" + key + "']");
+                    var $inputContainer = $inputElement.parent();
+                    $inputContainer.find(".help-inline").remove();
+                    var $errorEl = $("<span>", {class: "help-inline error", text: value});
+                    $inputContainer.append($errorEl).addClass("error");
+                }
+                _.each(errors, markErrors);
+            },
+
 });
 
 /* XOSItemView