diff --git a/main.go b/main.go
index 613affd..88abc1f 100644
--- a/main.go
+++ b/main.go
@@ -65,6 +65,7 @@ func validateFile(f io.Reader, regs []registry.Registry, k8sVersion string, c *c
 		}
 	}
 
+	// Cache both found & not found
 	c.Set(cacheKey, schema)
 
 	if err != nil { // Not found
@@ -94,6 +95,7 @@ func realMain() int {
 	var skipKinds, k8sVersion, outputFormat string
 	var printSummary, strict bool
 	var nWorkers int
+	var quiet bool
 
 	flag.BoolVar(&printSummary, "printsummary", false, "print a summary at the end")
 	flag.Var(&files, "file", "file to validate (can be specified multiple times)")
@@ -104,14 +106,15 @@ func realMain() int {
 	flag.StringVar(&skipKinds, "skipKinds", "", "comma-separated list of kinds to ignore")
 	flag.BoolVar(&strict, "strict", false, "activate strict mode")
 	flag.StringVar(&outputFormat, "output", "text", "output format - text, json")
+	flag.BoolVar(&quiet, "quiet", false, "quiet output - only print invalid files, and errors")
 	flag.Parse()
 
 	var o output.Output
 	switch {
 	case outputFormat == "text":
-		o = output.NewTextOutput(printSummary)
+		o = output.NewTextOutput(printSummary, quiet)
 	case outputFormat == "json":
-		o = output.NewJSONOutput(printSummary)
+		o = output.NewJSONOutput(printSummary, quiet)
 	default:
 		log.Fatalf("-output must be text or json")
 	}
diff --git a/pkg/cache/main.go b/pkg/cache/main.go
index aef9c9a..f34288a 100644
--- a/pkg/cache/main.go
+++ b/pkg/cache/main.go
@@ -24,7 +24,7 @@ func Key(resourceKind, resourceAPIVersion, k8sVersion string) string {
 func (c *SchemaCache) Get(key string) (*gojsonschema.Schema, bool) {
 	c.RLock()
 	defer c.RUnlock()
-	schema, ok :=  c.schemas[key]
+	schema, ok := c.schemas[key]
 	return schema, ok
 }
 
diff --git a/pkg/output/json.go b/pkg/output/json.go
index 357a066..b5a0f1a 100644
--- a/pkg/output/json.go
+++ b/pkg/output/json.go
@@ -3,6 +3,7 @@ package output
 import (
 	"encoding/json"
 	"fmt"
+	"sync"
 )
 
 type result struct {
@@ -12,35 +13,51 @@ type result struct {
 }
 
 type JSONOutput struct {
-	withSummary bool
-	results     []result
+	sync.Mutex
+	withSummary                         bool
+	quiet                               bool
+	results                             []result
+	nValid, nInvalid, nErrors, nSkipped int
 }
 
-func NewJSONOutput(withSummary bool) Output {
+func NewJSONOutput(withSummary bool, quiet bool) Output {
 	return &JSONOutput{
 		withSummary: withSummary,
+		quiet:       quiet,
 		results:     []result{},
+		nValid:      0,
+		nInvalid:    0,
+		nErrors:     0,
+		nSkipped:    0,
 	}
 }
 
 func (o *JSONOutput) Write(filename string, err error, skipped bool) {
+	o.Lock()
+	defer o.Unlock()
 	msg, st := "", ""
 
 	s := status(err, skipped)
 	switch {
 	case s == VALID:
 		st = "VALID"
+		o.nValid++
 	case s == INVALID:
 		st = "INVALID"
 		msg = err.Error()
+		o.nInvalid++
 	case s == ERROR:
 		st = "ERROR"
 		msg = err.Error()
+		o.nErrors++
 	case s == SKIPPED:
 		st = "SKIPPED"
+		o.nSkipped++
 	}
 
-	o.results = append(o.results, result{Filename: filename, Status: st, Msg: msg})
+	if !o.quiet || (s != VALID && s != SKIPPED) {
+		o.results = append(o.results, result{Filename: filename, Status: st, Msg: msg})
+	}
 }
 
 func (o *JSONOutput) Flush() {
@@ -58,25 +75,23 @@ func (o *JSONOutput) Flush() {
 			} `json:"summary"`
 		}{
 			Resources: o.results,
-		}
-
-		for _, r := range o.results {
-			switch {
-			case r.Status == "VALID":
-				jsonObj.Summary.Valid++
-			case r.Status == "INVALID":
-				jsonObj.Summary.Invalid++
-			case r.Status == "ERROR":
-				jsonObj.Summary.Errors++
-			case r.Status == "SKIPPED":
-				jsonObj.Summary.Skipped++
-			}
+			Summary: struct {
+				Valid   int `json:"valid"`
+				Invalid int `json:"invalid"`
+				Errors  int `json:"errors"`
+				Skipped int `json:"skipped"`
+			}{
+				Valid:   o.nValid,
+				Invalid: o.nInvalid,
+				Errors:  o.nErrors,
+				Skipped: o.nSkipped,
+			},
 		}
 
 		res, err = json.MarshalIndent(jsonObj, "", "  ")
 	} else {
 		jsonObj := struct {
-			Resources []result
+			Resources []result `json:"resources"`
 		}{
 			Resources: o.results,
 		}
diff --git a/pkg/output/text.go b/pkg/output/text.go
index 082cd7e..a1a0a7f 100644
--- a/pkg/output/text.go
+++ b/pkg/output/text.go
@@ -2,22 +2,37 @@ package output
 
 import (
 	"fmt"
+	"sync"
 )
 
 type TextOutput struct {
+	sync.Mutex
 	withSummary                         bool
+	quiet                               bool
 	nValid, nInvalid, nErrors, nSkipped int
 }
 
-func NewTextOutput(withSummary bool) Output {
-	return &TextOutput{withSummary, 0, 0, 0, 0}
+func NewTextOutput(withSummary, quiet bool) Output {
+	return &TextOutput{
+		withSummary: withSummary,
+		quiet:       quiet,
+		nValid:      0,
+		nInvalid:    0,
+		nErrors:     0,
+		nSkipped:    0,
+	}
 }
 
 func (o *TextOutput) Write(filename string, err error, skipped bool) {
+	o.Lock()
+	defer o.Unlock()
+
 	s := status(err, skipped)
 	switch {
 	case s == VALID:
-		fmt.Printf("file %s is valid\n", filename)
+		if !o.quiet {
+			fmt.Printf("file %s is valid\n", filename)
+		}
 		o.nValid++
 	case s == INVALID:
 		fmt.Printf("invalid resource: %s\n", err)
@@ -26,7 +41,9 @@ func (o *TextOutput) Write(filename string, err error, skipped bool) {
 		fmt.Printf("failed validating resource in file %s: %s\n", filename, err)
 		o.nErrors++
 	case s == SKIPPED:
-		fmt.Printf("skipping resource\n")
+		if !o.quiet {
+			fmt.Printf("skipping resource\n")
+		}
 		o.nSkipped++
 	}
 }