diff --git a/Package.swift b/Package.swift
index cf0befa..0a777c4 100644
--- a/Package.swift
+++ b/Package.swift
@@ -5,7 +5,7 @@ import PackageDescription
 let package = Package(
   name: "JSONSchema",
   platforms: [
-    .macOS(.v10_13),
+    .macOS(.v10_13), .iOS(.v11)
   ],
   products: [
     .library(name: "JSONSchema", targets: ["JSONSchema"]),
diff --git a/Sources/Applicators/anyOf.swift b/Sources/Applicators/anyOf.swift
index 4ebd045..4ed5fd9 100644
--- a/Sources/Applicators/anyOf.swift
+++ b/Sources/Applicators/anyOf.swift
@@ -1,12 +1,16 @@
+import Foundation
+
+
 func anyOf(context: Context, anyOf: Any, instance: Any, schema: [String: Any]) throws -> AnySequence<ValidationError> {
   guard let anyOf = anyOf as? [Any] else {
     return AnySequence(EmptyCollection())
   }
 
   if try !anyOf.contains(where: { try context.descend(instance: instance, subschema: $0).isValid }) {
+    let message = String(format: NSLocalizedString("%@ does not meet anyOf validation rules.", comment: ""), "\(instance)")
     return AnySequence([
       ValidationError(
-        "\(instance) does not meet anyOf validation rules.",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       ),
diff --git a/Sources/Applicators/contains.swift b/Sources/Applicators/contains.swift
index eae9dfc..94b7ae6 100644
--- a/Sources/Applicators/contains.swift
+++ b/Sources/Applicators/contains.swift
@@ -1,3 +1,6 @@
+import Foundation
+
+
 func contains(context: Context, contains: Any, instance: Any, schema: [String: Any]) throws -> AnySequence<ValidationError> {
   guard let instance = instance as? [Any] else {
     return AnySequence(EmptyCollection())
@@ -28,9 +31,10 @@ func contains(context: Context, contains: Any, instance: Any, schema: [String: A
     return try context.descend(instance: subinstance, subschema: contains).isValid
   }).count
   if let max = max, containsCount > max {
+    let message = String(format: NSLocalizedString("%@ does not match contains + maxContains %@.", comment: ""), "\(instance)", "\(max)")
     return AnySequence([
       ValidationError(
-        "\(instance) does not match contains + maxContains \(max)",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       )
@@ -41,9 +45,10 @@ func contains(context: Context, contains: Any, instance: Any, schema: [String: A
     return AnySequence(EmptyCollection())
   }
 
+  let message = String(format: NSLocalizedString("%@ does not match contains.", comment: ""), "\(instance)")
   return AnySequence([
     ValidationError(
-      "'\(instance) does not match contains",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
diff --git a/Sources/Applicators/dependencies.swift b/Sources/Applicators/dependencies.swift
index 65957e6..5e88c52 100644
--- a/Sources/Applicators/dependencies.swift
+++ b/Sources/Applicators/dependencies.swift
@@ -1,3 +1,6 @@
+import Foundation
+
+
 func dependencies(context: Context, dependencies: Any, instance: Any, schema: [String: Any]) throws -> AnySequence<ValidationError> {
   guard let dependencies = dependencies as? [String: Any] else {
     return AnySequence(EmptyCollection())
@@ -13,9 +16,10 @@ func dependencies(context: Context, dependencies: Any, instance: Any, schema: [S
     if let dependency = dependency as? [String] {
       for key in dependency {
         if !instance.keys.contains(key) {
+          let message = String(format: NSLocalizedString("'%@' is a dependency for '%@'.", comment: ""), key, property)
           results.append(AnySequence([
             ValidationError(
-              "'\(key)' is a dependency for '\(property)'",
+              message,
               instanceLocation: context.instanceLocation,
               keywordLocation: context.keywordLocation
             ),
diff --git a/Sources/Applicators/not.swift b/Sources/Applicators/not.swift
index ba0e768..b9e9087 100644
--- a/Sources/Applicators/not.swift
+++ b/Sources/Applicators/not.swift
@@ -1,11 +1,15 @@
+import Foundation
+
+
 func not(context: Context, not: Any, instance: Any, schema: [String: Any]) throws -> AnySequence<ValidationError> {
   guard try context.descend(instance: instance, subschema: not).isValid else {
     return AnySequence(EmptyCollection())
   }
 
+  let message = String(format: NSLocalizedString("'%@' does not match 'not' validation.", comment: ""), "\(instance)")
   return AnySequence([
     ValidationError(
-      "'\(instance)' does not match 'not' validation.",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
diff --git a/Sources/Applicators/oneOf.swift b/Sources/Applicators/oneOf.swift
index 14f81b0..10e69aa 100644
--- a/Sources/Applicators/oneOf.swift
+++ b/Sources/Applicators/oneOf.swift
@@ -1,12 +1,16 @@
+import Foundation
+
+
 func oneOf(context: Context, oneOf: Any, instance: Any, schema: [String: Any]) throws -> AnySequence<ValidationError> {
   guard let oneOf = oneOf as? [Any] else {
     return AnySequence(EmptyCollection())
   }
 
   if try oneOf.filter({ try context.descend(instance: instance, subschema: $0).isValid }).count != 1 {
+    let message = NSLocalizedString("Only one value from `oneOf` should be met.", comment: "")
     return AnySequence([
       ValidationError(
-        "Only one value from `oneOf` should be met",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       ),
diff --git a/Sources/Applicators/patternProperties.swift b/Sources/Applicators/patternProperties.swift
index 1b8dd6c..9a074d8 100644
--- a/Sources/Applicators/patternProperties.swift
+++ b/Sources/Applicators/patternProperties.swift
@@ -25,9 +25,10 @@ func patternProperties(context: Context, patternProperties: Any, instance: Any,
         results.append(try context.descend(instance: instance[key]!, subschema: schema))
       }
     } catch {
+      let message = String(format: NSLocalizedString("'%@' is not a valid regex pattern for patternProperties.", comment: ""), pattern)
       return AnySequence([
         ValidationError(
-          "[Schema] '\(pattern)' is not a valid regex pattern for patternProperties",
+          message,
           instanceLocation: context.instanceLocation,
           keywordLocation: context.keywordLocation
         ),
diff --git a/Sources/Format/date.swift b/Sources/Format/date.swift
index 6390404..05f5ab3 100644
--- a/Sources/Format/date.swift
+++ b/Sources/Format/date.swift
@@ -5,10 +5,11 @@ func validateDate(_ context: Context, _ value: String) -> AnySequence<Validation
   if let regularExpression = try? NSRegularExpression(pattern: "^\\d{4}-\\d{2}-\\d{2}$", options: []) {
     let range = NSRange(location: 0, length: value.utf16.count)
     let result = regularExpression.matches(in: value, options: [], range: range)
-    if result.isEmpty  {
+    if result.isEmpty {
+      let message = String(format: NSLocalizedString("'%@' is not a valid RFC 3339 formatted date.", comment: ""), value)
       return AnySequence([
         ValidationError(
-          "'\(value)' is not a valid RFC 3339 formatted date.",
+          message,
           instanceLocation: context.instanceLocation,
           keywordLocation: context.keywordLocation
         )
@@ -23,9 +24,10 @@ func validateDate(_ context: Context, _ value: String) -> AnySequence<Validation
     return AnySequence(EmptyCollection())
   }
 
+  let message = String(format: NSLocalizedString("'%@' is not a valid RFC 3339 formatted date.", comment: ""), value)
   return AnySequence([
     ValidationError(
-      "'\(value)' is not a valid RFC 3339 formatted date.",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
diff --git a/Sources/Format/duration.swift b/Sources/Format/duration.swift
index cda1777..ffa2faf 100644
--- a/Sources/Format/duration.swift
+++ b/Sources/Format/duration.swift
@@ -1,5 +1,6 @@
 import Foundation
 
+
 /*
 https://tools.ietf.org/html/rfc3339
 
@@ -17,6 +18,8 @@ Durations:
 
    duration          = "P" (dur-date / dur-time / dur-week)
 */
+
+
 var durationExpression: NSRegularExpression = {
   let second = "(\\d+S)"
   let minute = "((\\d+M)\(second)?)"
@@ -41,9 +44,10 @@ func isValidDuration(_ value: String) -> Bool {
 
 func validateDuration(_ context: Context, _ value: String) -> AnySequence<ValidationError> {
   guard isValidDuration(value) else {
+    let message = String(format: NSLocalizedString("'%@' is not a valid duration.", comment: ""), value)
     return AnySequence([
       ValidationError(
-        "'\(value)' is not a valid duration.",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       )
diff --git a/Sources/Format/time.swift b/Sources/Format/time.swift
index 18e7b56..c65967b 100644
--- a/Sources/Format/time.swift
+++ b/Sources/Format/time.swift
@@ -136,9 +136,10 @@ func validateTime(_ context: Context, _ value: String) -> AnySequence<Validation
     return AnySequence(EmptyCollection())
   }
 
+  let message = String(format: NSLocalizedString("'%@' is not a valid RFC 3339 formatted time.", comment: ""), value)
   return AnySequence([
     ValidationError(
-      "'\(value)' is not a valid RFC 3339 formatted time.",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
diff --git a/Sources/Localizable.strings b/Sources/Localizable.strings
new file mode 100644
index 0000000..2480f31
Binary files /dev/null and b/Sources/Localizable.strings differ
diff --git a/Sources/RefResolver.swift b/Sources/RefResolver.swift
index f268ea0..517de84 100644
--- a/Sources/RefResolver.swift
+++ b/Sources/RefResolver.swift
@@ -1,7 +1,7 @@
 import Foundation
 
 func urlSplitFragment(url: String) -> (String, String) {
-  guard let hashIndex = url.index(of: "#") else {
+  guard let hashIndex = url.firstIndex(of: "#") else {
     return (url, "")
   }
 
diff --git a/Sources/Validation/const.swift b/Sources/Validation/const.swift
index 9916675..bc0dcd6 100644
--- a/Sources/Validation/const.swift
+++ b/Sources/Validation/const.swift
@@ -5,10 +5,11 @@ func const(context: Context, const: Any, instance: Any, schema: [String: Any]) -
   if isEqual(instance as! NSObject, const as! NSObject) {
      return AnySequence(EmptyCollection())
   }
-
+  
+  let message = String(format: NSLocalizedString("'%@' is not equal to const '%@'", comment: ""), "\(instance)", "\(const)")
   return AnySequence([
     ValidationError(
-      "'\(instance)' is not equal to const '\(const)'",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
diff --git a/Sources/Validation/enum.swift b/Sources/Validation/enum.swift
index 879f99c..0bc4d65 100644
--- a/Sources/Validation/enum.swift
+++ b/Sources/Validation/enum.swift
@@ -11,9 +11,10 @@ func `enum`(context: Context, enum: Any, instance: Any, schema: [String: Any]) -
     return AnySequence(EmptyCollection())
   }
 
+  let message = String(format: NSLocalizedString("'%@' is not a valid enumeration value of '%@'", comment: ""), "\(instance)", "\(`enum`)")
   return AnySequence([
     ValidationError(
-      "'\(instance)' is not a valid enumeration value of '\(`enum`)'",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
diff --git a/Sources/Validation/minMaxItems.swift b/Sources/Validation/minMaxItems.swift
index b5a6eda..448a00b 100644
--- a/Sources/Validation/minMaxItems.swift
+++ b/Sources/Validation/minMaxItems.swift
@@ -1,3 +1,6 @@
+import Foundation
+
+
 func validateArrayLength(_ context: Context, _ rhs: Int, comparitor: @escaping ((Int, Int) -> Bool), error: String) -> (_ value: Any) -> AnySequence<ValidationError> {
   return { value in
     if let value = value as? [Any] {
@@ -22,7 +25,8 @@ func minItems(context: Context, minItems: Any, instance: Any, schema: [String: A
     return AnySequence(EmptyCollection())
   }
 
-  return validateArrayLength(context, minItems, comparitor: >=, error: "Length of array is smaller than the minimum \(minItems)")(instance)
+  let message = String(format: NSLocalizedString("Length of array is smaller than the minimum %@", comment: ""), "\(minItems)")
+  return validateArrayLength(context, minItems, comparitor: >=, error: message)(instance)
 }
 
 
@@ -30,6 +34,7 @@ func maxItems(context: Context, maxItems: Any, instance: Any, schema: [String: A
   guard let maxItems = maxItems as? Int else {
     return AnySequence(EmptyCollection())
   }
-
-  return validateArrayLength(context, maxItems, comparitor: <=, error: "Length of array is greater than maximum \(maxItems)")(instance)
+  
+  let message = String(format: NSLocalizedString("Length of array is greater than maximum %@", comment: ""), "\(maxItems)")
+  return validateArrayLength(context, maxItems, comparitor: <=, error: message)(instance)
 }
diff --git a/Sources/Validation/minMaxLength.swift b/Sources/Validation/minMaxLength.swift
index 0a1419f..fabd631 100644
--- a/Sources/Validation/minMaxLength.swift
+++ b/Sources/Validation/minMaxLength.swift
@@ -1,3 +1,6 @@
+import Foundation
+
+
 func validateLength(_ context: Context, _ comparitor: @escaping ((Int, Int) -> (Bool)), length: Int, error: String) -> (_ value: Any) -> AnySequence<ValidationError> {
   return { value in
     if let value = value as? String {
@@ -22,7 +25,8 @@ func minLength(context: Context, minLength: Any, instance: Any, schema: [String:
     return AnySequence(EmptyCollection())
   }
 
-  return validateLength(context, >=, length: minLength, error: "Length of string is smaller than minimum length \(minLength)")(instance)
+  let message = String(format: NSLocalizedString("Length of string is smaller than minimum length %@", comment: ""), "\(minLength)")
+  return validateLength(context, >=, length: minLength, error: message)(instance)
 }
 
 
@@ -31,5 +35,6 @@ func maxLength(context: Context, maxLength: Any, instance: Any, schema: [String:
     return AnySequence(EmptyCollection())
   }
 
-  return validateLength(context, <=, length: maxLength, error: "Length of string is larger than max length \(maxLength)")(instance)
+  let message = String(format: NSLocalizedString("Length of string is larger than max length %@", comment: ""), "\(maxLength)")
+  return validateLength(context, <=, length: maxLength, error: message)(instance)
 }
diff --git a/Sources/Validation/minMaxNumber.swift b/Sources/Validation/minMaxNumber.swift
index 0a66dc2..a8b7fad 100644
--- a/Sources/Validation/minMaxNumber.swift
+++ b/Sources/Validation/minMaxNumber.swift
@@ -1,3 +1,6 @@
+import Foundation
+
+
 func validateNumericLength(_ context: Context, _ length: Double, comparitor: @escaping ((Double, Double) -> (Bool)), exclusiveComparitor: @escaping ((Double, Double) -> (Bool)), exclusive: Bool?, error: String) -> (_ value: Any) -> AnySequence<ValidationError> {
   return { value in
     if let value = value as? Double {
@@ -34,7 +37,8 @@ func minimumDraft4(context: Context, minimum: Any, instance: Any, schema: [Strin
     return AnySequence(EmptyCollection())
   }
 
-  return validateNumericLength(context, minimum, comparitor: >=, exclusiveComparitor: >, exclusive: schema["exclusiveMinimum"] as? Bool, error: "Value is lower than minimum value of \(minimum)")(instance)
+  let message = String(format: NSLocalizedString("Value is lower than minimum value of %@", comment: ""), "\(minimum)")
+  return validateNumericLength(context, minimum, comparitor: >=, exclusiveComparitor: >, exclusive: schema["exclusiveMinimum"] as? Bool, error: message)(instance)
 }
 
 
@@ -43,7 +47,8 @@ func maximumDraft4(context: Context, maximum: Any, instance: Any, schema: [Strin
     return AnySequence(EmptyCollection())
   }
 
-  return validateNumericLength(context, maximum, comparitor: <=, exclusiveComparitor: <, exclusive: schema["exclusiveMaximum"] as? Bool, error: "Value exceeds maximum value of \(maximum)")(instance)
+  let message = String(format: NSLocalizedString("Value exceeds maximum value of %@", comment: ""), "\(maximum)")
+  return validateNumericLength(context, maximum, comparitor: <=, exclusiveComparitor: <, exclusive: schema["exclusiveMaximum"] as? Bool, error: message)(instance)
 }
 
 
@@ -52,7 +57,8 @@ func minimum(context: Context, minimum: Any, instance: Any, schema: [String: Any
     return AnySequence(EmptyCollection())
   }
 
-  return validateNumericLength(context, minimum, comparitor: >=, exclusiveComparitor: >, exclusive: false, error: "Value is lower than minimum value of \(minimum)")(instance)
+  let message = String(format: NSLocalizedString("Value is lower than minimum value of %@", comment: ""), "\(minimum)")
+  return validateNumericLength(context, minimum, comparitor: >=, exclusiveComparitor: >, exclusive: false, error: message)(instance)
 }
 
 
@@ -61,7 +67,8 @@ func maximum(context: Context, maximum: Any, instance: Any, schema: [String: Any
     return AnySequence(EmptyCollection())
   }
 
-  return validateNumericLength(context, maximum, comparitor: <=, exclusiveComparitor: <, exclusive: false, error: "Value exceeds maximum value of \(maximum)")(instance)
+  let message = String(format: NSLocalizedString("Value exceeds maximum value of %@", comment: ""), "\(maximum)")
+  return validateNumericLength(context, maximum, comparitor: <=, exclusiveComparitor: <, exclusive: false, error: message)(instance)
 }
 
 
@@ -70,7 +77,8 @@ func exclusiveMinimum(context: Context, minimum: Any, instance: Any, schema: [St
     return AnySequence(EmptyCollection())
   }
 
-  return validateNumericLength(context, minimum, comparitor: >=, exclusiveComparitor: >, exclusive: true, error: "Value is lower than exclusive minimum value of \(minimum)")(instance)
+  let message = String(format: NSLocalizedString("Value is lower than exclusive minimum value of %@", comment: ""), "\(minimum)")
+  return validateNumericLength(context, minimum, comparitor: >=, exclusiveComparitor: >, exclusive: true, error: message)(instance)
 }
 
 
@@ -79,5 +87,6 @@ func exclusiveMaximum(context: Context, maximum: Any, instance: Any, schema: [St
     return AnySequence(EmptyCollection())
   }
 
-  return validateNumericLength(context, maximum, comparitor: <=, exclusiveComparitor: <, exclusive: true, error: "Value exceeds exclusive maximum value of \(maximum)")(instance)
+  let message = String(format: NSLocalizedString("Value exceeds exclusive maximum value of %@", comment: ""), "\(maximum)")
+  return validateNumericLength(context, maximum, comparitor: <=, exclusiveComparitor: <, exclusive: true, error: message)(instance)
 }
diff --git a/Sources/Validation/minMaxProperties.swift b/Sources/Validation/minMaxProperties.swift
index ec7a0e2..9fcf890 100644
--- a/Sources/Validation/minMaxProperties.swift
+++ b/Sources/Validation/minMaxProperties.swift
@@ -1,3 +1,6 @@
+import Foundation
+
+
 func validatePropertiesLength(_ context: Context, _ length: Int, comparitor: @escaping ((Int, Int) -> (Bool)), error: String) -> (_ value: Any) -> AnySequence<ValidationError> {
   return { value in
     if let value = value as? [String: Any] {
@@ -21,8 +24,9 @@ func minProperties(context: Context, minProperties: Any, instance: Any, schema:
   guard let minProperties = minProperties as? Int else {
     return AnySequence(EmptyCollection())
   }
-
-  return validatePropertiesLength(context, minProperties, comparitor: <=, error: "Amount of properties is less than the required amount")(instance)
+  
+  let message = NSLocalizedString("Amount of properties is less than the required amount", comment: "")
+  return validatePropertiesLength(context, minProperties, comparitor: <=, error: message)(instance)
 }
 
 
@@ -31,5 +35,6 @@ func maxProperties(context: Context, maxProperties: Any, instance: Any, schema:
     return AnySequence(EmptyCollection())
   }
 
-  return validatePropertiesLength(context, maxProperties, comparitor: >=, error: "Amount of properties is greater than maximum permitted")(instance)
+  let message = NSLocalizedString("Amount of properties is greater than maximum permitted", comment: "")
+  return validatePropertiesLength(context, maxProperties, comparitor: >=, error: message)(instance)
 }
diff --git a/Sources/Validation/multipleOf.swift b/Sources/Validation/multipleOf.swift
index 4fc99b4..d3c2ceb 100644
--- a/Sources/Validation/multipleOf.swift
+++ b/Sources/Validation/multipleOf.swift
@@ -12,9 +12,10 @@ func multipleOf(context: Context, multipleOf: Any, instance: Any, schema: [Strin
 
   let result = instance / multipleOf
   if result != floor(result) {
+    let message = String(format: NSLocalizedString("%@ is not a multiple of %@", comment: ""), "\(instance)", "\(multipleOf)")
     return AnySequence([
       ValidationError(
-        "\(instance) is not a multiple of \(multipleOf)",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       )
diff --git a/Sources/Validation/pattern.swift b/Sources/Validation/pattern.swift
index 646994d..200df17 100644
--- a/Sources/Validation/pattern.swift
+++ b/Sources/Validation/pattern.swift
@@ -11,9 +11,10 @@ func pattern(context: Context, pattern: Any, instance: Any, schema: [String: Any
   }
 
   guard let expression = try? NSRegularExpression(pattern: pattern, options: NSRegularExpression.Options(rawValue: 0)) else {
+    let message = String(format: NSLocalizedString("Regex pattern '%@' is not valid", comment: ""), pattern)
     return AnySequence([
       ValidationError(
-        "[Schema] Regex pattern '\(pattern)' is not valid",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       )
@@ -22,9 +23,10 @@ func pattern(context: Context, pattern: Any, instance: Any, schema: [String: Any
 
   let range = NSMakeRange(0, instance.count)
   if expression.matches(in: instance, options: NSRegularExpression.MatchingOptions(rawValue: 0), range: range).count == 0 {
+    let message = String(format: NSLocalizedString("'%@' does not match pattern: '%@'", comment: ""), instance, pattern)
     return AnySequence([
       ValidationError(
-        "'\(instance)' does not match pattern: '\(pattern)'",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       )
diff --git a/Sources/Validation/required.swift b/Sources/Validation/required.swift
index b75153a..6eb2795 100644
--- a/Sources/Validation/required.swift
+++ b/Sources/Validation/required.swift
@@ -1,3 +1,6 @@
+import Foundation
+
+
 func required(context: Context, required: Any, instance: Any, schema: [String: Any]) throws -> AnySequence<ValidationError> {
   guard let instance = instance as? [String: Any] else {
     return AnySequence(EmptyCollection())
@@ -10,8 +13,9 @@ func required(context: Context, required: Any, instance: Any, schema: [String: A
 
   return AnySequence(required.compactMap { key -> ValidationError? in
     guard !instance.keys.contains(key) else { return nil }
+    let message = String(format: NSLocalizedString("Required property '%@' is missing", comment: ""), key)
     return ValidationError(
-      "Required property '\(key)' is missing",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
diff --git a/Sources/Validation/uniqueItems.swift b/Sources/Validation/uniqueItems.swift
index ce95a84..6c56034 100644
--- a/Sources/Validation/uniqueItems.swift
+++ b/Sources/Validation/uniqueItems.swift
@@ -13,9 +13,10 @@ func uniqueItems(context: Context, uniqueItems: Any, instance: Any, schema: [Str
   var items: [Any] = []
   for item in instance {
     if items.contains(where: { isEqual(item as! NSObject, $0 as! NSObject) }) {
+      let message = String(format: NSLocalizedString("%@ does not have unique items", comment: ""), "\(instance)")
       return AnySequence([
         ValidationError(
-          "\(instance) does not have unique items",
+          message,
           instanceLocation: context.instanceLocation,
           keywordLocation: context.keywordLocation
         )
diff --git a/Sources/Validator.swift b/Sources/Validator.swift
index 13016c5..cacd4b2 100644
--- a/Sources/Validator.swift
+++ b/Sources/Validator.swift
@@ -18,9 +18,10 @@ class Context {
         return AnySequence(EmptyCollection())
       }
 
+      let message = NSLocalizedString("Falsy schema", comment: "")
       return AnySequence([
         ValidationError(
-          "Falsy schema",
+          message,
           instanceLocation: instanceLocation,
           keywordLocation: keywordLocation
         )
diff --git a/Sources/Validators.swift b/Sources/Validators.swift
index b289ce6..faa9655 100644
--- a/Sources/Validators.swift
+++ b/Sources/Validators.swift
@@ -43,9 +43,10 @@ func type(context: Context, type: Any, instance: Any, schema: [String: Any]) ->
   }
 
   let types = type.map { "'\($0)'" }.joined(separator: ", ")
+  let message = String(format: NSLocalizedString("'%@' is not of type %@", comment: ""), "\(instance)", "\(types)")
   return AnySequence([
     ValidationError(
-      "'\(instance)' is not of type \(types)",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
@@ -164,9 +165,10 @@ extension Sequence where Iterator.Element == ValidationError {
 
 func unsupported(_ keyword: String) -> (_ context: Context, _ value: Any, _ instance: Any, _ schema: [String: Any]) -> AnySequence<ValidationError> {
   return { (context, _, _, _) in
+    let message = String(format: NSLocalizedString("'%@' is not supported.", comment: ""), keyword)
     return AnySequence([
       ValidationError(
-        "'\(keyword)' is not supported.",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       ),
diff --git a/Sources/format.swift b/Sources/format.swift
index 136c990..c12ff7c 100644
--- a/Sources/format.swift
+++ b/Sources/format.swift
@@ -11,9 +11,10 @@ func format(context: Context, format: Any, instance: Any, schema: [String: Any])
   }
 
   guard let validator = context.validator.formats[format] else {
+    let message = String(format: NSLocalizedString("'format' validation of '%@' is not yet supported.", comment: ""), format)
     return AnySequence([
       ValidationError(
-        "'format' validation of '\(format)' is not yet supported.",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       )
@@ -31,9 +32,10 @@ func validateIPv4(_ context: Context, _ value: String) -> AnySequence<Validation
     }
   }
 
+  let message = String(format: NSLocalizedString("'%@' is not a IPv4 address.", comment: ""), value)
   return AnySequence([
     ValidationError(
-      "'\(value)' is not a IPv4 address.",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
@@ -49,9 +51,10 @@ func validateIPv6(_ context: Context, _ value: String) -> AnySequence<Validation
     }
   }
 
+  let message = String(format: NSLocalizedString("'%@' is not a value address.", comment: ""), value)
   return AnySequence([
     ValidationError(
-      "'\(value)' is not a value address.",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
@@ -72,9 +75,10 @@ func validateURI(_ context: Context, _ value: String) -> AnySequence<ValidationE
     }
   }
 
+  let message = String(format: NSLocalizedString("'%@' is not a valid uri.", comment: ""), value)
   return AnySequence([
     ValidationError(
-      "'\(value)' is not a valid uri.",
+      message,
       instanceLocation: context.instanceLocation,
       keywordLocation: context.keywordLocation
     )
@@ -84,9 +88,10 @@ func validateURI(_ context: Context, _ value: String) -> AnySequence<ValidationE
 
 func validateUUID(_ context: Context, _ value: String) -> AnySequence<ValidationError> {
   if UUID(uuidString: value) == nil {
+    let message = String(format: NSLocalizedString("'%@' is not a valid uuid.", comment: ""), value)
     return AnySequence([
       ValidationError(
-        "'\(value)' is not a valid uuid.",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       )
@@ -101,9 +106,10 @@ func validateRegex(_ context: Context, _ value: String) -> AnySequence<Validatio
   do {
     _ = try NSRegularExpression(pattern: value)
   } catch {
+    let message = String(format: NSLocalizedString("'%@' is not a valid regex.", comment: ""), value)
     return AnySequence([
       ValidationError(
-        "'\(value)' is not a valid regex.",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       )
@@ -120,9 +126,10 @@ func validateJSONPointer(_ context: Context, _ value: String) -> AnySequence<Val
   }
 
   if !value.hasPrefix("/") {
+    let message = String(format: NSLocalizedString("'%@' is not a valid json-pointer.", comment: ""), value)
     return AnySequence([
       ValidationError(
-        "'\(value)' is not a valid json-pointer.",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       )
@@ -135,9 +142,10 @@ func validateJSONPointer(_ context: Context, _ value: String) -> AnySequence<Val
       .contains("~")
   {
     // unescaped ~
+    let message = String(format: NSLocalizedString("'%@' is not a valid json-pointer.", comment: ""), value)
     return AnySequence([
       ValidationError(
-        "'\(value)' is not a valid json-pointer.",
+        message,
         instanceLocation: context.instanceLocation,
         keywordLocation: context.keywordLocation
       )