diff --git a/benchmarks/pom.xml b/benchmarks/pom.xml
index b7965af9215..e0add430148 100644
--- a/benchmarks/pom.xml
+++ b/benchmarks/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin</groupId>
     <artifactId>zipkin-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>benchmarks</artifactId>
diff --git a/pom.xml b/pom.xml
index 3560f8dbc99..5c3c40ad5a5 100755
--- a/pom.xml
+++ b/pom.xml
@@ -19,7 +19,7 @@
 
   <groupId>io.zipkin</groupId>
   <artifactId>zipkin-parent</artifactId>
-  <version>3.0.7-SNAPSHOT</version>
+  <version>3.1.0-SNAPSHOT</version>
   <packaging>pom</packaging>
 
   <modules>
diff --git a/zipkin-collector/activemq/pom.xml b/zipkin-collector/activemq/pom.xml
index 87223e23fa3..89e38104b40 100644
--- a/zipkin-collector/activemq/pom.xml
+++ b/zipkin-collector/activemq/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin.zipkin2</groupId>
     <artifactId>zipkin-collector-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>zipkin-collector-activemq</artifactId>
diff --git a/zipkin-collector/core/pom.xml b/zipkin-collector/core/pom.xml
index 6985e9bb89a..db41b211f70 100644
--- a/zipkin-collector/core/pom.xml
+++ b/zipkin-collector/core/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin.zipkin2</groupId>
     <artifactId>zipkin-collector-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>zipkin-collector</artifactId>
diff --git a/zipkin-collector/kafka/pom.xml b/zipkin-collector/kafka/pom.xml
index ae9128d8154..d1bd184dd00 100644
--- a/zipkin-collector/kafka/pom.xml
+++ b/zipkin-collector/kafka/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin.zipkin2</groupId>
     <artifactId>zipkin-collector-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>zipkin-collector-kafka</artifactId>
diff --git a/zipkin-collector/pom.xml b/zipkin-collector/pom.xml
index 709c4eccddc..317785acbd1 100644
--- a/zipkin-collector/pom.xml
+++ b/zipkin-collector/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin</groupId>
     <artifactId>zipkin-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <groupId>io.zipkin.zipkin2</groupId>
diff --git a/zipkin-collector/rabbitmq/pom.xml b/zipkin-collector/rabbitmq/pom.xml
index 515f7e6addc..3704320c101 100644
--- a/zipkin-collector/rabbitmq/pom.xml
+++ b/zipkin-collector/rabbitmq/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin.zipkin2</groupId>
     <artifactId>zipkin-collector-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>zipkin-collector-rabbitmq</artifactId>
diff --git a/zipkin-collector/scribe/pom.xml b/zipkin-collector/scribe/pom.xml
index cf2b439514a..d52ecd6e473 100644
--- a/zipkin-collector/scribe/pom.xml
+++ b/zipkin-collector/scribe/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin.zipkin2</groupId>
     <artifactId>zipkin-collector-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>zipkin-collector-scribe</artifactId>
diff --git a/zipkin-junit5/pom.xml b/zipkin-junit5/pom.xml
index 41348cb0c1a..a97caf9ca49 100644
--- a/zipkin-junit5/pom.xml
+++ b/zipkin-junit5/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin</groupId>
     <artifactId>zipkin-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <groupId>io.zipkin.zipkin2</groupId>
diff --git a/zipkin-lens/pom.xml b/zipkin-lens/pom.xml
index 3ff3f90ce67..612cf07ccbc 100644
--- a/zipkin-lens/pom.xml
+++ b/zipkin-lens/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin</groupId>
     <artifactId>zipkin-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>zipkin-lens</artifactId>
diff --git a/zipkin-server/README.md b/zipkin-server/README.md
index 4cd9a77159f..dec0a93225c 100644
--- a/zipkin-server/README.md
+++ b/zipkin-server/README.md
@@ -111,7 +111,8 @@ exposition [text format version 0.0.4](https://prometheus.io/docs/instrumenting/
 
 ### Collector
 
-Collector metrics are broken down by transport. The following are exported to the "/metrics" endpoint:
+Collector metrics are broken down by transport, where the defaults are "http" and "grpc". The
+following are exported to the "/metrics" endpoint:
 
 | Metric                                               | Description                                                                           |
 |------------------------------------------------------|---------------------------------------------------------------------------------------|
@@ -378,7 +379,9 @@ As this feature is experimental, it is not recommended to run this in production
 ## Collector
 
 ### HTTP Collector
-The HTTP collector is enabled by default. It accepts spans via `POST /api/v1/spans` and `POST /api/v2/spans`.
+The HTTP collector is enabled by default. It accepts spans via `POST /api/v1/spans` and
+`POST /api/v2/spans`, on the `${QUERY_PORT}` which defaults to 9411.
+
 The HTTP collector supports the following configuration:
 
 | Property                        | Environment Variable     | Description                                              |
@@ -494,17 +497,18 @@ Example usage:
 $ RABBIT_ADDRESSES=localhost java -jar zipkin.jar
 ```
 
-### gRPC Collector (Experimental)
-You can enable a gRPC span collector endpoint by setting `COLLECTOR_GRPC_ENABLED=true`. The
-`zipkin.proto3.SpanService/Report` endpoint will run on the same port as normal HTTP (9411).
+### gRPC Collector
 
-Example usage:
+The gRPC collector is enabled by default. It accepts spans via `zipkin.proto3.SpanService/Report`,
+on the `${QUERY_PORT}` which defaults to 9411.
 
-```bash
-$ COLLECTOR_GRPC_ENABLED=true java -jar zipkin.jar
-```
+The gRPC collector supports the following configuration:
+
+| Variable                 | Description                                            |
+|--------------------------|--------------------------------------------------------|
+| `COLLECTOR_GRPC_ENABLED` | `false` disables the gRPC service. Defaults to `true`. |
 
-As this service is experimental, it is not recommended to run this in production environments.
+The proto definition is here: https://github.com/openzipkin/zipkin-api/blob/master/zipkin.proto
 
 ## Service Registration
 
diff --git a/zipkin-server/pom.xml b/zipkin-server/pom.xml
index 86e6138e273..14e4b7b9791 100644
--- a/zipkin-server/pom.xml
+++ b/zipkin-server/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin</groupId>
     <artifactId>zipkin-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>zipkin-server</artifactId>
diff --git a/zipkin-server/src/main/java/zipkin2/server/internal/ZipkinGrpcCollector.java b/zipkin-server/src/main/java/zipkin2/server/internal/ZipkinGrpcCollector.java
index 421eff52e38..a36323156f6 100644
--- a/zipkin-server/src/main/java/zipkin2/server/internal/ZipkinGrpcCollector.java
+++ b/zipkin-server/src/main/java/zipkin2/server/internal/ZipkinGrpcCollector.java
@@ -30,7 +30,7 @@
 import zipkin2.storage.StorageComponent;
 
 /** Collector for receiving spans on a gRPC endpoint. */
-@ConditionalOnProperty(name = "zipkin.collector.grpc.enabled") // disabled by default
+@ConditionalOnProperty(name = "zipkin.collector.grpc.enabled", matchIfMissing = true)
 final class ZipkinGrpcCollector {
 
   @Bean ArmeriaServerConfigurator grpcCollectorConfigurator(StorageComponent storage,
@@ -56,7 +56,8 @@ static final class SpanService extends AbstractUnsafeUnaryGrpcService {
       this.metrics = metrics;
     }
 
-    @Override protected CompletionStage<ByteBuf> handleMessage(ServiceRequestContext ctx, ByteBuf bytes) {
+    @Override
+    protected CompletionStage<ByteBuf> handleMessage(ServiceRequestContext ctx, ByteBuf bytes) {
       metrics.incrementMessages();
       metrics.incrementBytes(bytes.readableBytes());
 
diff --git a/zipkin-server/src/main/resources/zipkin-server-shared.yml b/zipkin-server/src/main/resources/zipkin-server-shared.yml
index 255b0c8819d..54de6903d71 100644
--- a/zipkin-server/src/main/resources/zipkin-server-shared.yml
+++ b/zipkin-server/src/main/resources/zipkin-server-shared.yml
@@ -26,11 +26,11 @@ zipkin:
       # Optional password to connect to the broker
       password: ${ACTIVEMQ_PASSWORD:}
     http:
-      # Set to false to disable creation of spans via HTTP collector API
+      # Set false to disable creation of spans via HTTP collector API
       enabled: ${COLLECTOR_HTTP_ENABLED:${HTTP_COLLECTOR_ENABLED:true}}
     grpc:
-      # Set to true to enable the GRPC collector
-      enabled: ${COLLECTOR_GRPC_ENABLED:false}
+      # Set false to disable the GRPC collector
+      enabled: ${COLLECTOR_GRPC_ENABLED:true}
     kafka:
       enabled: ${COLLECTOR_KAFKA_ENABLED:true}
       # Kafka bootstrap broker list, comma-separated host:port values. Setting this activates the
diff --git a/zipkin-server/src/test/java/zipkin2/server/internal/ITZipkinGrpcCollector.java b/zipkin-server/src/test/java/zipkin2/server/internal/ITZipkinGrpcCollector.java
index 34cf413bb65..8847999f830 100644
--- a/zipkin-server/src/test/java/zipkin2/server/internal/ITZipkinGrpcCollector.java
+++ b/zipkin-server/src/test/java/zipkin2/server/internal/ITZipkinGrpcCollector.java
@@ -32,7 +32,6 @@
 import zipkin2.codec.SpanBytesDecoder;
 import zipkin2.codec.SpanBytesEncoder;
 import zipkin2.proto3.ListOfSpans;
-import zipkin2.proto3.ReportResponse;
 import zipkin2.storage.InMemoryStorage;
 
 import static okhttp3.Protocol.H2_PRIOR_KNOWLEDGE;
@@ -48,7 +47,6 @@
     "server.port=0",
     "spring.config.name=zipkin-server",
     "spring.main.banner-mode=off",
-    "zipkin.collector.grpc.enabled=true"
   }
 )
 class ITZipkinGrpcCollector {
@@ -61,17 +59,17 @@ class ITZipkinGrpcCollector {
 
   OkHttpClient client = new OkHttpClient.Builder().protocols(List.of(H2_PRIOR_KNOWLEDGE)).build();
 
-  ListOfSpans request;
+  ListOfSpans grpcRequest;
 
   @BeforeEach void sanityCheckCodecCompatible() throws IOException {
-    request = ListOfSpans.ADAPTER.decode(SpanBytesEncoder.PROTO3.encodeList(TestObjects.TRACE));
+    grpcRequest = ListOfSpans.ADAPTER.decode(SpanBytesEncoder.PROTO3.encodeList(TestObjects.TRACE));
 
-    assertThat(SpanBytesDecoder.PROTO3.decodeList(request.encode()))
+    assertThat(SpanBytesDecoder.PROTO3.decodeList(grpcRequest.encode()))
       .containsExactlyElementsOf(TestObjects.TRACE); // sanity check codec compatible
   }
 
   @Test void report_trace() throws IOException {
-    callReport(request); // Result is effectively void
+    callReport(grpcRequest); // Result is effectively void
 
     awaitSpans();
 
@@ -80,30 +78,36 @@ class ITZipkinGrpcCollector {
   }
 
   @Test void report_emptyIsOk() throws IOException {
-
     callReport(new ListOfSpans.Builder().build());
   }
 
-  ReportResponse callReport(ListOfSpans spans) throws IOException {
-    Buffer requestBody = new Buffer();
-    requestBody.writeByte(0 /* compressedFlag */);
-    Buffer encodedMessage = new Buffer();
-    ListOfSpans.ADAPTER.encode(encodedMessage, spans);
-    requestBody.writeInt((int) encodedMessage.size());
-    requestBody.writeAll(encodedMessage);
-
-    Response response = client.newCall(new Request.Builder()
-      .url(url(server, "/zipkin.proto3.SpanService/Report"))
-      .addHeader("te", "trailers")
-      .post(RequestBody.create(requestBody.snapshot(), MediaType.get("application/grpc")))
-      .build())
-      .execute();
-
-    BufferedSource responseBody = response.body().source();
-    assertThat((int) responseBody.readByte()).isEqualTo(0); // uncompressed
-    long encodedLength = responseBody.readInt() & 0xffffffffL;
-
-    return ReportResponse.ADAPTER.decode(responseBody);
+  void callReport(ListOfSpans spans) throws IOException {
+    try (Buffer requestBody = new Buffer(); Buffer encodedMessage = new Buffer()) {
+      requestBody.writeByte(0 /* compressedFlag */);
+
+      ListOfSpans.ADAPTER.encode(encodedMessage, spans);
+      requestBody.writeInt((int) encodedMessage.size());
+      requestBody.writeAll(encodedMessage);
+
+      Request request = new Request.Builder()
+        .url(url(server, "/zipkin.proto3.SpanService/Report"))
+        .addHeader("te", "trailers")
+        .post(RequestBody.create(requestBody.snapshot(), MediaType.get("application/grpc")))
+        .build();
+      try (Response response = client.newCall(request).execute();
+           BufferedSource responseBody = response.body().source()) {
+
+        // We expect this is a valid gRPC over HTTP2 response (Length-Prefixed-Message).
+        // See https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#responses
+        byte compressedFlag = responseBody.readByte();
+        long messageLength = responseBody.readInt() & 0xffffffffL;
+        assertThat(responseBody.exhausted()).isTrue(); // We expect a single response
+
+        // Now, verify the Length-Prefixed-Message
+        assertThat(compressedFlag).isZero(); // server didn't compress
+        assertThat(messageLength).isZero(); // there are no fields in ReportResponse
+      }
+    }
   }
 
   void awaitSpans() {
diff --git a/zipkin-server/src/test/java/zipkin2/server/internal/prometheus/ITZipkinMetrics.java b/zipkin-server/src/test/java/zipkin2/server/internal/prometheus/ITZipkinMetrics.java
index b56baa34ba0..37b015145b2 100644
--- a/zipkin-server/src/test/java/zipkin2/server/internal/prometheus/ITZipkinMetrics.java
+++ b/zipkin-server/src/test/java/zipkin2/server/internal/prometheus/ITZipkinMetrics.java
@@ -144,7 +144,14 @@ String scrape() throws Exception {
     String metrics = getAsString("/metrics");
 
     assertThat(readJson(metrics)).containsOnlyKeys(
-      "gauge.zipkin_collector.message_spans.http"
+      "gauge.zipkin_collector.message_spans.grpc"
+      , "gauge.zipkin_collector.message_bytes.grpc"
+      , "counter.zipkin_collector.messages.grpc"
+      , "counter.zipkin_collector.bytes.grpc"
+      , "counter.zipkin_collector.spans.grpc"
+      , "counter.zipkin_collector.messages_dropped.grpc"
+      , "counter.zipkin_collector.spans_dropped.grpc"
+      , "gauge.zipkin_collector.message_spans.http"
       , "gauge.zipkin_collector.message_bytes.http"
       , "counter.zipkin_collector.messages.http"
       , "counter.zipkin_collector.bytes.http"
diff --git a/zipkin-storage/cassandra/pom.xml b/zipkin-storage/cassandra/pom.xml
index 34501a30255..afd9187a7b6 100644
--- a/zipkin-storage/cassandra/pom.xml
+++ b/zipkin-storage/cassandra/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin.zipkin2</groupId>
     <artifactId>zipkin-storage-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>zipkin-storage-cassandra</artifactId>
diff --git a/zipkin-storage/elasticsearch/pom.xml b/zipkin-storage/elasticsearch/pom.xml
index 93540b6cd46..f24470cb4de 100644
--- a/zipkin-storage/elasticsearch/pom.xml
+++ b/zipkin-storage/elasticsearch/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin.zipkin2</groupId>
     <artifactId>zipkin-storage-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>zipkin-storage-elasticsearch</artifactId>
diff --git a/zipkin-storage/mysql-v1/pom.xml b/zipkin-storage/mysql-v1/pom.xml
index 8493686fcc5..1ed1b2aaa83 100644
--- a/zipkin-storage/mysql-v1/pom.xml
+++ b/zipkin-storage/mysql-v1/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin.zipkin2</groupId>
     <artifactId>zipkin-storage-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <artifactId>zipkin-storage-mysql-v1</artifactId>
diff --git a/zipkin-storage/pom.xml b/zipkin-storage/pom.xml
index 4ea3044f031..131f2c3be38 100644
--- a/zipkin-storage/pom.xml
+++ b/zipkin-storage/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin</groupId>
     <artifactId>zipkin-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <groupId>io.zipkin.zipkin2</groupId>
diff --git a/zipkin-tests/pom.xml b/zipkin-tests/pom.xml
index e76c1b9d16d..f4c20fb7e2a 100644
--- a/zipkin-tests/pom.xml
+++ b/zipkin-tests/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin</groupId>
     <artifactId>zipkin-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <groupId>io.zipkin.zipkin2</groupId>
diff --git a/zipkin/pom.xml b/zipkin/pom.xml
index 7e7cc8a889a..861529b669e 100644
--- a/zipkin/pom.xml
+++ b/zipkin/pom.xml
@@ -20,7 +20,7 @@
   <parent>
     <groupId>io.zipkin</groupId>
     <artifactId>zipkin-parent</artifactId>
-    <version>3.0.7-SNAPSHOT</version>
+    <version>3.1.0-SNAPSHOT</version>
   </parent>
 
   <groupId>io.zipkin.zipkin2</groupId>