diff --git a/README.md b/README.md
index 23a9f67..0739622 100644
--- a/README.md
+++ b/README.md
@@ -140,6 +140,46 @@ Example Output:
 {"ip":"1.1.1.1","spur":{"as":{"number":13335,"organization":"Cloudflare, Inc."},"infrastructure":"DATACENTER","ip":"1.1.1.1","location":{"city":"Anycast","country":"ZZ","state":"Anycast"},"organization":"Taguchi Digital Marketing System"}}
 ```
 
+### Greynoise Psychic
+[Greynoise](https://greynoise.io) is an IP intelligence feed that provides metadata like threat classification and associated CVE's.
+Their Psychic data downloads provide their data feed in a database suitable for offline data enrichment.
+To use their download with `zannotate`, you'll want to download an `.mmdb` formatted file using your GreyNoise API key. 
+As of April 2026, signing up with a free account gives access to data downloads.
+
+0. Sign up for a free GreyNoise account [here](https://www.greynoise.io).
+1. Copy API key from the appropriate [section of your account](https://viz.greynoise.io/workspace/api-key).
+2. Download a `mmdb` file. Details on download parameters 
+(The below command is for downloading data for a single date - April 7th, 2026 - you can also download data for a range of days and for models of various levels of detail.
+See GreyNoise's Psychic [documentation](https://psychic.labs.greynoise.io) for more details.
+```shell
+curl -H "key: GREYNOISE_API_KEY_HERE" \
+           https://psychic.labs.greynoise.io/v1/psychic/download/2026-04-07/3/mmdb \
+           -o /tmp/m3.mmdb
+```
+
+3. Test GreyNoise data enrichment:
+
+> [!NOTE]
+> The below examples are using the exact data download from the above `curl` command. What results you see will depend on the data downloaded.
+
+```shell
+echo "14.1.105.157" | zannotate --greynoise --greynoise-database=/tmp/m3.mmdb  
+````
+Example Output:
+```json
+{"greynoise":{"classification":"malicious","cves":["CVE-2015-2051","CVE-2016-20016","CVE-2018-10561","CVE-2018-10562","CVE-2016-6277","CVE-2024-12847"],"date":"2026-04-07","handshake_complete":true,"last_seen":"2026-04-07T00:00:00Z","seen":true,"tags":["Mirai TCP Scanner","Mirai","Telnet Protocol","Generic IoT Default Password Attempt","Web Crawler","Generic Suspicious Linux Command in Request","HNAP Crawler","Telnet Login Attempt","D-Link Devices HNAP SOAPAction Header RCE Attempt","MVPower CCTV DVR RCE CVE-2016-20016 Attempt","JAWS Webserver RCE","GPON CVE-2018-10561 Router Worm","Generic ${IFS} Use in RCE Attempt","CCTV-DVR RCE","NETGEAR Command Injection CVE-2016-6277","NETGEAR DGN setup.cgi CVE-2024-12847 Command Execution Attempt","CGI Script Scanner"],"actor":"unknown"},"ip":"14.1.105.157"}
+```
+
+Note that many IPs will not be in the GreyNoise dataset, so you may see output like the following:
+```shell
+echo "1.1.1.1" | zannotate --greynoise --greynoise-database=/tmp/m3.mmdb  
+```
+
+```json
+{"ip":"1.1.1.1","greynoise":null}
+```
+
+
 # Input/Output
 
 ## Output
diff --git a/data-snapshots/greynoise.mmdb b/data-snapshots/greynoise.mmdb
new file mode 100644
index 0000000..5e42160
Binary files /dev/null and b/data-snapshots/greynoise.mmdb differ
diff --git a/greynoise_psychic.go b/greynoise_psychic.go
new file mode 100644
index 0000000..809526a
--- /dev/null
+++ b/greynoise_psychic.go
@@ -0,0 +1,120 @@
+/*
+ * ZAnnotate Copyright 2026 Regents of the University of Michigan
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy
+ * of the License at http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package zannotate
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"net"
+	"net/netip"
+	"os"
+
+	"github.com/oschwald/maxminddb-golang/v2"
+	log "github.com/sirupsen/logrus"
+)
+
+type GreyNoiseAnnotatorFactory struct {
+	BasePluginConf
+	DBPath      string // path to the .mmdb path
+	greynoiseDB *maxminddb.Reader
+}
+
+// GreyNoise Annotator Factory (Global)
+
+func (a *GreyNoiseAnnotatorFactory) MakeAnnotator(i int) Annotator {
+	var v GreyNoiseAnnotator
+	v.Factory = a
+	v.Id = i
+	return &v
+}
+
+func (a *GreyNoiseAnnotatorFactory) Initialize(_ *GlobalConf) error {
+	if len(a.DBPath) == 0 {
+		return errors.New("greynoise database path is required when greynoise annotator is enabled, use --greynoise-database")
+	}
+	data, err := os.ReadFile(a.DBPath) // ensure DB is read in-memory
+	if err != nil {
+		return fmt.Errorf("unable to read greynoise database at %s: %w", a.DBPath, err)
+	}
+	a.greynoiseDB, err = maxminddb.OpenBytes(data)
+	if err != nil {
+		return fmt.Errorf("unable to open greynoise database at %s: %w", a.DBPath, err)
+	}
+	return nil
+}
+
+func (a *GreyNoiseAnnotatorFactory) GetWorkers() int {
+	return a.Threads
+}
+
+func (a *GreyNoiseAnnotatorFactory) Close() error {
+	if err := a.greynoiseDB.Close(); err != nil {
+		return fmt.Errorf("unable to close greynoise database at %s: %w", a.DBPath, err)
+	}
+	return nil
+}
+
+func (a *GreyNoiseAnnotatorFactory) IsEnabled() bool {
+	return a.Enabled
+}
+
+func (a *GreyNoiseAnnotatorFactory) AddFlags(flags *flag.FlagSet) {
+	// Reverse DNS Lookup
+	flags.BoolVar(&a.Enabled, "greynoise", false, "greynoise psychic data intelligence")
+	flags.StringVar(&a.DBPath, "greynoise-database", "", "path to greynoise psychic .mmdb file")
+	flags.IntVar(&a.Threads, "greynoise-threads", 2, "how many enrichment threads to use")
+}
+
+// GreyNoiseAnnotator (Per-Worker)
+type GreyNoiseAnnotator struct {
+	Factory *GreyNoiseAnnotatorFactory
+	Id      int
+}
+
+func (a *GreyNoiseAnnotator) Initialize() (err error) {
+	return nil
+}
+
+func (a *GreyNoiseAnnotator) GetFieldName() string {
+	return "greynoise"
+}
+
+// Annotate performs a reverse DNS lookup for the given IP address and returns the results.
+// If an error occurs or a lookup fails, it returns nil
+func (a *GreyNoiseAnnotator) Annotate(ip net.IP) interface{} {
+	addr, ok := netip.AddrFromSlice(ip)
+	if !ok {
+		log.Debugf("unable to convert IP %s to address", ip)
+		return nil
+	}
+	addr = addr.Unmap()
+	var result any
+	err := a.Factory.greynoiseDB.Lookup(addr).Decode(&result)
+	if err != nil {
+		log.Debugf("unable to annotate IP (%s): %v", addr, err)
+		return nil
+	}
+	return result
+}
+
+func (a *GreyNoiseAnnotator) Close() error {
+	return nil
+}
+
+func init() {
+	s := new(GreyNoiseAnnotatorFactory)
+	RegisterAnnotator(s)
+}
diff --git a/greynoise_psychic_test.go b/greynoise_psychic_test.go
new file mode 100644
index 0000000..d4467b1
--- /dev/null
+++ b/greynoise_psychic_test.go
@@ -0,0 +1,91 @@
+/*
+ * ZAnnotate Copyright 2025 Regents of the University of Michigan
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy
+ * of the License at http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+package zannotate
+
+import (
+	"math/rand/v2"
+	"net"
+	"reflect"
+	"testing"
+)
+
+// TestGreyNoiseAnnotator tests that given a database file and a known IP, the annotator returns the expected values for that IP in the DB
+func TestGreyNoiseAnnotator(t *testing.T) {
+	expectedFields := map[string]any{
+		"actor":              "Stanford University",
+		"classification":     "benign",
+		"date":               "2026-04-07",
+		"handshake_complete": true,
+		"last_seen":          "2026-04-07T00:00:00Z",
+		"seen":               true,
+		"tags":               []any{"Stanford University", "RDP Crawler", "RDP Protocol"},
+	}
+	factory := &GreyNoiseAnnotatorFactory{DBPath: "./data-snapshots/greynoise.mmdb"}
+	err := factory.Initialize(nil)
+	if err != nil {
+		t.Fatalf("Error initializing greynoise annotator factory: %v", err)
+	}
+	a := factory.MakeAnnotator(0).(*GreyNoiseAnnotator)
+	err = a.Initialize()
+	if err != nil {
+		t.Fatalf("Error initializing greynoise annotator: %v", err)
+	}
+
+	ip := "171.67.71.209"
+	res := a.Annotate(net.ParseIP(ip))
+	if res == nil {
+		t.Fatalf("GreyNoiseAnnotator failed to annotate %s", ip)
+	}
+
+	for field, expected := range expectedFields {
+		actual, ok := res.(map[string]any)[field]
+		if !ok {
+			t.Errorf("missing expected field %q", field)
+			continue
+		}
+		if !reflect.DeepEqual(actual, expected) {
+			t.Errorf("field %q: expected %v (%T), got %v (%T)", field, expected, expected, actual, actual)
+		}
+	}
+}
+
+func BenchmarkGreyNoiseAnnotator(b *testing.B) {
+	factory := &GreyNoiseAnnotatorFactory{DBPath: "./data-snapshots/greynoise.mmdb"}
+	err := factory.Initialize(nil)
+	if err != nil {
+		b.Fatalf("Error initializing greynoise annotator factory: %v", err)
+	}
+	a := factory.MakeAnnotator(0).(*GreyNoiseAnnotator)
+	err = a.Initialize()
+	if err != nil {
+		b.Fatalf("Error initializing greynoise annotator: %v", err)
+	}
+
+	// Pre-generate random IPs so generation is not part of the benchmark
+	ips := make([]net.IP, 1000)
+	for i := range ips {
+		ips[i] = net.IPv4(
+			byte(rand.IntN(256)),
+			byte(rand.IntN(256)),
+			byte(rand.IntN(256)),
+			byte(rand.IntN(256)),
+		)
+	}
+
+	b.ResetTimer()
+	b.ReportAllocs()
+	for i := range b.N {
+		a.Annotate(ips[i%len(ips)])
+	}
+}