diff --git a/proxy/interceptors/npm_registry.go b/proxy/interceptors/npm_registry.go
index addf73f..6e9161f 100644
--- a/proxy/interceptors/npm_registry.go
+++ b/proxy/interceptors/npm_registry.go
@@ -37,6 +37,7 @@ type NpmRegistryInterceptor struct {
 }
 
 var _ proxy.Interceptor = (*NpmRegistryInterceptor)(nil)
+var _ proxy.MITMDecider = (*NpmRegistryInterceptor)(nil)
 
 // NewNpmRegistryInterceptor creates a new NPM registry interceptor
 func NewNpmRegistryInterceptor(
@@ -60,6 +61,15 @@ func (i *NpmRegistryInterceptor) Name() string {
 	return "npm-registry-interceptor"
 }
 
+func (i *NpmRegistryInterceptor) ShouldMITM(ctx *proxy.RequestContext) bool {
+	config := npmRegistryDomains.GetConfigForHostname(ctx.Hostname)
+	if config == nil {
+		return false
+	}
+
+	return config.SupportedForAnalysis
+}
+
 // ShouldIntercept determines if this interceptor should handle the given request
 func (i *NpmRegistryInterceptor) ShouldIntercept(ctx *proxy.RequestContext) bool {
 	return npmRegistryDomains.ContainsHostname(ctx.Hostname)
diff --git a/proxy/interceptors/npm_registry_test.go b/proxy/interceptors/npm_registry_test.go
new file mode 100644
index 0000000..9eda84f
--- /dev/null
+++ b/proxy/interceptors/npm_registry_test.go
@@ -0,0 +1,54 @@
+package interceptors
+
+import (
+	"testing"
+
+	"github.com/safedep/pmg/proxy"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNpmRegistryInterceptor_ShouldMITM(t *testing.T) {
+	interceptor := NewNpmRegistryInterceptor(nil, nil, nil, nil)
+
+	tests := []struct {
+		name     string
+		hostname string
+		wantMITM bool
+	}{
+		{"public registry is MITM'd", "registry.npmjs.org", true},
+		{"yarn registry is MITM'd", "registry.yarnpkg.com", true},
+		{"github packages is NOT MITM'd", "npm.pkg.github.com", false},
+		{"github blob storage is NOT MITM'd", "pkg-npm.githubusercontent.com", false},
+		{"unknown registry is NOT MITM'd", "registry.example.com", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ctx := &proxy.RequestContext{Hostname: tt.hostname}
+			assert.Equal(t, tt.wantMITM, interceptor.ShouldMITM(ctx))
+		})
+	}
+}
+
+func TestNpmRegistryInterceptor_ShouldIntercept(t *testing.T) {
+	interceptor := NewNpmRegistryInterceptor(nil, nil, nil, nil)
+
+	tests := []struct {
+		name          string
+		hostname      string
+		wantIntercept bool
+	}{
+		{"public registry", "registry.npmjs.org", true},
+		{"yarn registry", "registry.yarnpkg.com", true},
+		{"github packages", "npm.pkg.github.com", true},
+		{"github blob storage", "pkg-npm.githubusercontent.com", true},
+		{"unknown registry", "registry.example.com", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ctx := &proxy.RequestContext{Hostname: tt.hostname}
+			assert.Equal(t, tt.wantIntercept, interceptor.ShouldIntercept(ctx))
+		})
+	}
+}
diff --git a/proxy/interceptors/pypi_registry.go b/proxy/interceptors/pypi_registry.go
index 5ba7a42..3ebad2a 100644
--- a/proxy/interceptors/pypi_registry.go
+++ b/proxy/interceptors/pypi_registry.go
@@ -38,6 +38,7 @@ type PypiRegistryInterceptor struct {
 }
 
 var _ proxy.Interceptor = (*PypiRegistryInterceptor)(nil)
+var _ proxy.MITMDecider = (*PypiRegistryInterceptor)(nil)
 
 // NewPypiRegistryInterceptor creates a new PyPI registry interceptor
 func NewPypiRegistryInterceptor(
@@ -61,6 +62,15 @@ func (i *PypiRegistryInterceptor) Name() string {
 	return "pypi-registry-interceptor"
 }
 
+func (i *PypiRegistryInterceptor) ShouldMITM(ctx *proxy.RequestContext) bool {
+	config := pypiRegistryDomains.GetConfigForHostname(ctx.Hostname)
+	if config == nil {
+		return false
+	}
+
+	return config.SupportedForAnalysis
+}
+
 // ShouldIntercept determines if this interceptor should handle the given request
 func (i *PypiRegistryInterceptor) ShouldIntercept(ctx *proxy.RequestContext) bool {
 	return pypiRegistryDomains.ContainsHostname(ctx.Hostname)
diff --git a/proxy/interceptors/pypi_registry_test.go b/proxy/interceptors/pypi_registry_test.go
new file mode 100644
index 0000000..d379a1c
--- /dev/null
+++ b/proxy/interceptors/pypi_registry_test.go
@@ -0,0 +1,31 @@
+package interceptors
+
+import (
+	"testing"
+
+	"github.com/safedep/pmg/proxy"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPypiRegistryInterceptor_ShouldMITM(t *testing.T) {
+	interceptor := NewPypiRegistryInterceptor(nil, nil, nil, nil)
+
+	tests := []struct {
+		name     string
+		hostname string
+		wantMITM bool
+	}{
+		{"pypi files is MITM'd", "files.pythonhosted.org", true},
+		{"pypi org is MITM'd", "pypi.org", true},
+		{"test pypi is NOT MITM'd", "test.pypi.org", false},
+		{"test pypi files is NOT MITM'd", "test-files.pythonhosted.org", false},
+		{"unknown registry is NOT MITM'd", "registry.example.com", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ctx := &proxy.RequestContext{Hostname: tt.hostname}
+			assert.Equal(t, tt.wantMITM, interceptor.ShouldMITM(ctx))
+		})
+	}
+}