diff --git a/index.js b/index.js
index 11036a1..eb404ef 100644
--- a/index.js
+++ b/index.js
@@ -1,9 +1,11 @@
 const CloudEvent = require("./lib/cloudevent.js");
 const HTTPReceiver = require("./lib/bindings/http/http_receiver.js");
 const HTTPEmitter = require("./lib/bindings/http/http_emitter.js");
+const Constants = require("./lib/bindings/http/constants.js");
 
 module.exports = {
   CloudEvent,
   HTTPReceiver,
-  HTTPEmitter
+  HTTPEmitter,
+  Constants
 };
diff --git a/lib/bindings/http/constants.js b/lib/bindings/http/constants.js
index ab8fead..89542bc 100644
--- a/lib/bindings/http/constants.js
+++ b/lib/bindings/http/constants.js
@@ -3,6 +3,9 @@ module.exports = Object.freeze({
   HEADERS: "headers",
   CHARSET_DEFAULT: "utf-8",
 
+  BINARY: "binary",
+  STRUCTURED: "structured",
+
   SPEC_V03: "0.3",
   SPEC_V1: "1.0",
 
diff --git a/lib/bindings/http/http_receiver.js b/lib/bindings/http/http_receiver.js
index 803401d..78f5631 100644
--- a/lib/bindings/http/http_receiver.js
+++ b/lib/bindings/http/http_receiver.js
@@ -4,6 +4,8 @@ const V1Binary = require("./receiver_binary_1.js");
 const V1Structured = require("./receiver_structured_1.js");
 const ValidationError = require("../../validation_error.js");
 const {
+  BINARY,
+  STRUCTURED,
   SPEC_V03,
   SPEC_V1,
   HEADER_CONTENT_TYPE,
@@ -59,16 +61,16 @@ class HTTPReceiver {
 function getMode(headers) {
   const contentType = headers[HEADER_CONTENT_TYPE];
   if (contentType && contentType.startsWith(MIME_CE)) {
-    return "structured";
+    return STRUCTURED;
   }
   if (headers[BINARY_HEADERS_1.ID]) {
-    return "binary";
+    return BINARY;
   }
   throw new ValidationError("no cloud event detected");
 }
 
 function getVersion(mode, headers, body) {
-  if (mode === "binary") {
+  if (mode === BINARY) {
     // Check the headers for the version
     const versionHeader = headers[DEFAULT_SPEC_VERSION_HEADER];
     if (versionHeader) {
diff --git a/lib/bindings/http/unmarshaller.js b/lib/bindings/http/unmarshaller.js
index dd071df..9bf97c2 100644
--- a/lib/bindings/http/unmarshaller.js
+++ b/lib/bindings/http/unmarshaller.js
@@ -3,14 +3,13 @@ const {
   MIME_CE,
   MIME_CE_JSON,
   MIME_JSON,
-  MIME_OCTET_STREAM
+  MIME_OCTET_STREAM,
+  BINARY,
+  STRUCTURED
 } = require("./constants.js");
 const Commons = require("./commons.js");
 const ValidationError = require("../../validation_error.js");
 
-const STRUCTURED = "structured";
-const BINARY = "binary";
-
 const allowedBinaryContentTypes = [
   MIME_JSON,
   MIME_OCTET_STREAM
diff --git a/test/bindings/http/unmarshaller_0_3_tests.js b/test/bindings/http/unmarshaller_0_3_tests.js
index 55ff87e..77462e1 100644
--- a/test/bindings/http/unmarshaller_0_3_tests.js
+++ b/test/bindings/http/unmarshaller_0_3_tests.js
@@ -11,7 +11,8 @@ const schemaurl = "http://cloudevents.io/schema.json";
 const subject = "subject.ext";
 const {
   BINARY_HEADERS_03,
-  HEADER_CONTENT_TYPE
+  HEADER_CONTENT_TYPE,
+  BINARY
 } = require("../../../lib/bindings/http/constants.js");
 
 const ceContentType = "application/json";
@@ -182,7 +183,7 @@ describe("HTTP Transport Binding Unmarshaller for CloudEvents v0.3", () => {
         [BINARY_HEADERS_03.TIME]: "2019-06-16T11:42:00Z",
         [BINARY_HEADERS_03.SCHEMA_URL]: "http://schema.registry/v1",
         [HEADER_CONTENT_TYPE]: "application/json",
-        [BINARY_HEADERS_03.CONTENT_ENCONDING]: "binary"
+        [BINARY_HEADERS_03.CONTENT_ENCONDING]: BINARY
       };
 
       expect(() => un.unmarshall(payload, attributes)).to
diff --git a/test/constants_test.js b/test/constants_test.js
new file mode 100644
index 0000000..55d2078
--- /dev/null
+++ b/test/constants_test.js
@@ -0,0 +1,191 @@
+const expect = require("chai").expect;
+
+const {
+  HEADERS,
+  CHARSET_DEFAULT,
+  BINARY,
+  STRUCTURED,
+  SPEC_V03,
+  SPEC_V1,
+  DEFAULT_SPEC_VERSION_HEADER,
+  ENCODING_BASE64,
+  DATA_ATTRIBUTE,
+  MIME_JSON,
+  MIME_OCTET_STREAM,
+  MIME_CE,
+  MIME_CE_JSON,
+  HEADER_CONTENT_TYPE,
+  DEFAULT_CONTENT_TYPE,
+  DEFAULT_CE_CONTENT_TYPE,
+  BINARY_HEADERS_03,
+  STRUCTURED_ATTRS_03,
+  BINARY_HEADERS_1,
+  STRUCTURED_ATTRS_1
+} = require("../").Constants;
+
+describe("Constants exposed by top level exports", () => {
+  it("Exports a HEADERS constant", () => {
+    expect(HEADERS).to.equal("headers");
+  });
+  it("Exports a CHARSET_DEFAULT constant", () => {
+    expect(CHARSET_DEFAULT).to.equal("utf-8");
+  });
+  it("Exports a BINARY constant", () => {
+    expect(BINARY).to.equal("binary");
+  });
+  it("Exports a STRUCTURED constant", () => {
+    expect(STRUCTURED).to.equal("structured");
+  });
+  it("Exports a SPEC_V03 constant", () => {
+    expect(SPEC_V03).to.equal("0.3");
+  });
+  it("Exports a SPEC_V1 constant", () => {
+    expect(SPEC_V1).to.equal("1.0");
+  });
+  it("Exports a DEFAULT_SPEC_VERSION_HEADER constant", () => {
+    expect(DEFAULT_SPEC_VERSION_HEADER).to.equal("ce-specversion");
+  });
+  it("Exports an ENCODING_BASE64 constant", () => {
+    expect(ENCODING_BASE64).to.equal("base64");
+  });
+  it("Exports a DATA_ATTRIBUTE constant", () => {
+    expect(DATA_ATTRIBUTE).to.equal("data");
+  });
+  it("Exports a MIME_JSON constant", () => {
+    expect(MIME_JSON).to.equal("application/json");
+  });
+  it("Exports a MIME_OCTET_STREAM constant", () => {
+    expect(MIME_OCTET_STREAM).to.equal("application/octet-stream");
+  });
+  it("Exports a MIME_CE constant", () => {
+    expect(MIME_CE).to.equal("application/cloudevents");
+  });
+  it("Exports a MIME_CE_JSON constant", () => {
+    expect(MIME_CE_JSON).to.equal("application/cloudevents+json");
+  });
+  it("Exports a HEADER_CONTENT_TYPE constant", () => {
+    expect(HEADER_CONTENT_TYPE).to.equal("content-type");
+  });
+  it("Exports a DEFAULT_CONTENT_TYPE constant", () => {
+    expect(DEFAULT_CONTENT_TYPE).to.equal(`${MIME_JSON}; charset=${CHARSET_DEFAULT}`);
+  });
+  it("Exports a DEFAULT_CE_CONTENT_TYPE constant", () => {
+    expect(DEFAULT_CE_CONTENT_TYPE).to.equal(`${MIME_CE_JSON}; charset=${CHARSET_DEFAULT}`);
+  });
+  describe("V0.3 binary headers constants", () => {
+    it("Provides a TYPE header", () => {
+      expect(BINARY_HEADERS_03.TYPE).to.equal("ce-type");
+    });
+    it("Provides a SPEC_VERSION header", () => {
+      expect(BINARY_HEADERS_03.SPEC_VERSION).to.equal("ce-specversion");
+    });
+    it("Provides a SOURCE header", () => {
+      expect(BINARY_HEADERS_03.SOURCE).to.equal("ce-source");
+    });
+    it("Provides an ID header", () => {
+      expect(BINARY_HEADERS_03.ID).to.equal("ce-id");
+    });
+    it("Provides a TIME header", () => {
+      expect(BINARY_HEADERS_03.TIME).to.equal("ce-time");
+    });
+    it("Provides a SCHEMA_URL header", () => {
+      expect(BINARY_HEADERS_03.SCHEMA_URL).to.equal("ce-schemaurl");
+    });
+    it("Provides a CONTENT_ENCODING header", () => {
+      expect(BINARY_HEADERS_03.CONTENT_ENCONDING).to.equal("ce-datacontentencoding");
+    });
+    it("Provides a SUBJECT header", () => {
+      expect(BINARY_HEADERS_03.SUBJECT).to.equal("ce-subject");
+    });
+    it("Provides an EXTENSIONS_PREFIX constant", () => {
+      expect(BINARY_HEADERS_03.EXTENSIONS_PREFIX).to.equal("ce-");
+    });
+  });
+  describe("V0.3 structured attributes constants", () => {
+    it("Provides a TYPE attribute", () => {
+      expect(STRUCTURED_ATTRS_03.TYPE).to.equal("type");
+    });
+    it("Provides a SPEC_VERSION attribute", () => {
+      expect(STRUCTURED_ATTRS_03.SPEC_VERSION).to.equal("specversion");
+    });
+    it("Provides a SOURCE attribute", () => {
+      expect(STRUCTURED_ATTRS_03.SOURCE).to.equal("source");
+    });
+    it("Provides an ID attribute", () => {
+      expect(STRUCTURED_ATTRS_03.ID).to.equal("id");
+    });
+    it("Provides a TIME attribute", () => {
+      expect(STRUCTURED_ATTRS_03.TIME).to.equal("time");
+    });
+    it("Provides a SCHEMA_URL attribute", () => {
+      expect(STRUCTURED_ATTRS_03.SCHEMA_URL).to.equal("schemaurl");
+    });
+    it("Provides a CONTENT_ENCODING attribute", () => {
+      expect(STRUCTURED_ATTRS_03.CONTENT_ENCONDING).to.equal("datacontentencoding");
+    });
+    it("Provides a SUBJECT attribute", () => {
+      expect(STRUCTURED_ATTRS_03.SUBJECT).to.equal("subject");
+    });
+    it("Provides a DATA attribute", () => {
+      expect(STRUCTURED_ATTRS_03.DATA).to.equal("data");
+    });
+  });
+  describe("V01 binary headers constants", () => {
+    it("Provides a TYPE header", () => {
+      expect(BINARY_HEADERS_1.TYPE).to.equal("ce-type");
+    });
+    it("Provides a SPEC_VERSION header", () => {
+      expect(BINARY_HEADERS_1.SPEC_VERSION).to.equal("ce-specversion");
+    });
+    it("Provides a SOURCE header", () => {
+      expect(BINARY_HEADERS_1.SOURCE).to.equal("ce-source");
+    });
+    it("Provides an ID header", () => {
+      expect(BINARY_HEADERS_1.ID).to.equal("ce-id");
+    });
+    it("Provides a TIME header", () => {
+      expect(BINARY_HEADERS_1.TIME).to.equal("ce-time");
+    });
+    it("Provides a DATA_SCHEMA header", () => {
+      expect(BINARY_HEADERS_1.DATA_SCHEMA).to.equal("ce-dataschema");
+    });
+    it("Provides a SUBJECT header", () => {
+      expect(BINARY_HEADERS_1.SUBJECT).to.equal("ce-subject");
+    });
+    it("Provides an EXTENSIONS_PREFIX constant", () => {
+      expect(BINARY_HEADERS_1.EXTENSIONS_PREFIX).to.equal("ce-");
+    });
+  });
+  describe("V1 structured attributes constants", () => {
+    it("Provides a TYPE attribute", () => {
+      expect(STRUCTURED_ATTRS_1.TYPE).to.equal("type");
+    });
+    it("Provides a SPEC_VERSION attribute", () => {
+      expect(STRUCTURED_ATTRS_1.SPEC_VERSION).to.equal("specversion");
+    });
+    it("Provides a SOURCE attribute", () => {
+      expect(STRUCTURED_ATTRS_1.SOURCE).to.equal("source");
+    });
+    it("Provides an ID attribute", () => {
+      expect(STRUCTURED_ATTRS_1.ID).to.equal("id");
+    });
+    it("Provides a TIME attribute", () => {
+      expect(STRUCTURED_ATTRS_1.TIME).to.equal("time");
+    });
+    it("Provides a DATA_SCHEMA attribute", () => {
+      expect(STRUCTURED_ATTRS_1.DATA_SCHEMA).to.equal("dataschema");
+    });
+    it("Provides a CONTENT_TYPE attribute", () => {
+      expect(STRUCTURED_ATTRS_1.CONTENT_TYPE).to.equal("datacontenttype");
+    });
+    it("Provides a SUBJECT attribute", () => {
+      expect(STRUCTURED_ATTRS_1.SUBJECT).to.equal("subject");
+    });
+    it("Provides a DATA attribute", () => {
+      expect(STRUCTURED_ATTRS_1.DATA).to.equal("data");
+    });
+    it("Provides a DATA_BASE64 attribute", () => {
+      expect(STRUCTURED_ATTRS_1.DATA_BASE64).to.equal("data_base64");
+    });
+  });
+});
\ No newline at end of file
diff --git a/test/spec_0_3_tests.js b/test/spec_0_3_tests.js
index 4de79d6..6ab6a24 100644
--- a/test/spec_0_3_tests.js
+++ b/test/spec_0_3_tests.js
@@ -4,7 +4,8 @@ const { CloudEvent } = require("../index.js");
 const {
   MIME_JSON,
   ENCODING_BASE64,
-  SPEC_V03
+  SPEC_V03,
+  BINARY
 } = require("../lib/bindings/http/constants.js");
 const ValidationError = require("../lib/validation_error.js");
 
@@ -155,7 +156,7 @@ describe("CloudEvents Spec v0.3", () => {
       it("should throw an error when is a unsupported encoding", () => {
         cloudevent
           .data("Y2xvdWRldmVudHMK")
-          .dataContentEncoding("binary");
+          .dataContentEncoding(BINARY);
         expect(cloudevent.format.bind(cloudevent))
           .to.throw(ValidationError, "invalid payload");
         delete cloudevent.spec.payload.datacontentencoding;