diff --git a/README.md b/README.md
index de592292..13a873b5 100644
--- a/README.md
+++ b/README.md
@@ -43,6 +43,7 @@ Supported features of the specification:
 | - [Jakarta Restful WS](http/restful-ws) |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |          - [Basic](http/basic)          |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |           - [Spring](spring)            |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|           - [http4k][http4k]<sup>†</sup>           |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |            JSON Event Format            |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |    - [Jackson](formats/json-jackson)    |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |     [Kafka Protocol Binding](kafka)     |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
@@ -50,6 +51,8 @@ Supported features of the specification:
 |          NATS Protocol Binding          |                          :x:                          |                          :x:                          |
 |                Web hook                 |                          :x:                          |                          :x:                          |
 
+<sub>† Source/artifacts hosted externally</sub>
+
 ## Documentation
 
 Documentation is available at https://cloudevents.github.io/sdk-java/.
@@ -70,9 +73,9 @@ You can check out the examples in the [examples](examples) directory.
 
 ## Used By
 
-| [Occurrent](https://occurrent.org)                                                                                                                                                                                                              | [Knative Eventing](https://github.com/knative-sandbox/eventing-kafka-broker)                                                                                   |
-| ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| <a href="https://occurrent.org"><img src="https://raw.githubusercontent.com/johanhaleby/occurrent/master/occurrent-logo-196x196.png" width="98" height="98" alt="Occurrent" title="Occurrent - Event Sourcing Utilities for the JVM"></img></a> | <a href="https://github.com/knative-sandbox/eventing-kafka-broker"><img src="https://cloudevents.io/img/logos/integrations/knative.png" height="98"></img></a> |
+| [Occurrent](https://occurrent.org) | [Knative Eventing](https://github.com/knative-sandbox/eventing-kafka-broker )| [http4k][http4k] |
+| ---------------------------------- | ---------------------------------------------------------------------------- | ---------------|
+| <a href="https://occurrent.org"><img src="https://raw.githubusercontent.com/johanhaleby/occurrent/master/occurrent-logo-196x196.png" width="98" height="98" alt="Occurrent" title="Occurrent - Event Sourcing Utilities for the JVM"></img></a> | <a href="https://github.com/knative-sandbox/eventing-kafka-broker"><img src="https://cloudevents.io/img/logos/integrations/knative.png" height="98"></img></a> | <a href="https://www.http4k.org/guide/modules/cloud_events/"><img src="https://http4k.org/img/favicon-310.png" height="98" alt="http4k" title="http4k"></img></a> | |
 
 ## Community
 
@@ -99,3 +102,5 @@ projects are
 for how PR reviews and approval, and our
 [Code of Conduct](https://github.com/cloudevents/spec/blob/master/community/GOVERNANCE.md#additional-information)
 information.
+
+[http4k]: https://www.http4k.org/guide/modules/cloud_events/
diff --git a/docs/index.md b/docs/index.md
index 68bea773..69ace8d0 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -37,6 +37,7 @@ Using the Java SDK you can:
 | - [Jakarta Restful WS](http-jakarta-restful-ws.md) |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |              - [Basic](http-basic.md)              |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |               - [Spring](spring.md)                |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
+|               - [http4k][http4k]<sup>†</sup>       |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |                 JSON Event Format                  |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |            - [Jackson](json-jackson.md)            |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
 |         [Kafka Protocol Binding](kafka.md)         |                  :heavy_check_mark:                   |                  :heavy_check_mark:                   |
@@ -44,6 +45,8 @@ Using the Java SDK you can:
 |               NATS Protocol Binding                |                          :x:                          |                          :x:                          |
 |                      Web hook                      |                          :x:                          |                          :x:                          |
 
+<sub>† Source/artifacts hosted externally</sub>
+
 ## Get Started
 
 In order to start learning how to create, access and manipulate `CloudEvent`s,
@@ -113,3 +116,4 @@ You can look at the latest published artifacts on
 [`cloudevents-kafka`]: https://github.com/cloudevents/sdk-java/tree/master/kafka
 [`cloudevents-amqp-proton`]: https://github.com/cloudevents/sdk-java/tree/master/amqp
 [`cloudevents-spring`]: https://github.com/cloudevents/sdk-java/tree/master/spring
+[http4k]: https://www.http4k.org/guide/modules/cloud_events/