diff --git a/contrib/html/openapi.yaml b/contrib/html/openapi.yaml
index a4ab246f..b2a677f8 100644
--- a/contrib/html/openapi.yaml
+++ b/contrib/html/openapi.yaml
@@ -123,6 +123,28 @@ paths:
         500:
           description: Circuit or message not found.
           content: { }
+  /datatypes:
+    get:
+      summary: Get all known field data types.
+      responses:
+        200:
+          description: Success.
+          content:
+            application/json;charset=utf-8:
+              schema:
+                $ref: '#/components/schemas/DataTypes'
+        400:
+          description: Invalid request parameters.
+          content: { }
+        403:
+          description: User not authorized.
+          content: { }
+        404:
+          description: Circuit or message not found.
+          content: { }
+        500:
+          description: General error.
+          content: { }
   /{file}:
     get:
       summary: Retrieve a particular file.
@@ -289,51 +311,6 @@ components:
           type: integer
           description: the time in UTC seconds of the last update of any message.
           example: 1493483370
-        types:
-          type: array
-          description: the known field data types (only with definition and without since).
-          items:
-            type: object
-            properties:
-              type:
-                type: string
-                description: the type name.
-                example: UCH
-              isbits:
-                type: boolean
-                description: true when the length is in bits.
-              isadjustable:
-                type: boolean
-                description: whether the length is adjustable.
-              isignored:
-                type: boolean
-                description: whether the result is ignored.
-              length:
-                type: number
-                minimum: -1
-                maximum: 31
-                description: the field length in bytes (-1 for remainder, number
-                  of bits when isbits is true).
-              result:
-                enum:
-                  - void
-                  - string
-                  - number
-                  - date
-                  - time
-                  - datetime
-                description: the result type.
-              divisor:
-                type: number
-                description: the divisor for numeric types (only if applicable, positive
-                  for divisor, negative for reciprocal i.e. 1/-divisor).
-              precision:
-                type: number
-                description: the precision (number of fraction digits) when divisor is >1.
-            required:
-              - type
-              - isbits
-              - length
     Circuit:
       type: object
       properties:
@@ -497,6 +474,54 @@ components:
         comment:
           type: string
           description: the field comment.
+    DataType:
+      description: a known field data type.
+      type: object
+      properties:
+        type:
+          type: string
+          description: the type name.
+          example: UCH
+        isbits:
+          type: boolean
+          description: true when the length is in bits.
+        isadjustable:
+          type: boolean
+          description: whether the length is adjustable.
+        isignored:
+          type: boolean
+          description: whether the result is ignored.
+        length:
+          type: number
+          minimum: -1
+          maximum: 31
+          description: the field length in bytes (-1 for remainder, number
+            of bits when isbits is true).
+        result:
+          enum:
+            - void
+            - string
+            - number
+            - date
+            - time
+            - datetime
+          description: the result type.
+        divisor:
+          type: number
+          description: the divisor for numeric types (only if applicable, positive
+            for divisor, negative for reciprocal i.e. 1/-divisor).
+        precision:
+          type: number
+          description: the precision (number of fraction digits) when divisor is >1.
+      required:
+        - type
+        - isbits
+        - length
+    DataTypes:
+      type: array
+      description: the known field data types.
+      items:
+        $ref: '#/components/schemas/DataType'
     Data:
       required:
         - global
diff --git a/src/ebusd/mainloop.cpp b/src/ebusd/mainloop.cpp
index 90dc8697..82c9b286 100644
--- a/src/ebusd/mainloop.cpp
+++ b/src/ebusd/mainloop.cpp
@@ -2000,10 +2000,6 @@ bool parseBoolQuery(const string& value) {
 }
 
 result_t MainLoop::executeGet(const vector<string>& args, bool* connected, ostringstream* ostream) {
-  bool required = false, full = false, withWrite = false, raw = false;
-  bool withDefinition = false;
-  string newDefinition;
-  OutputFormat verbosity = OF_NAMES;
   time_t maxAge = -1;
   size_t argPos = 1;
   string uri = args[argPos++];
@@ -2018,6 +2014,10 @@ result_t MainLoop::executeGet(const vector<string>& args, bool* connected, ostri
       circuit = uri.substr(6, pos - 6);
       name = uri.substr(pos + 1);
     }
+    bool required = false, full = false, withWrite = false, raw = false;
+    bool withDefinition = false;
+    string newDefinition;
+    OutputFormat verbosity = OF_NAMES;
     time_t since = 0;
     size_t pollPriority = 0;
     bool exact = false;
@@ -2199,13 +2199,8 @@ result_t MainLoop::executeGet(const vector<string>& args, bool* connected, ostri
       *ostream << ",\n  \"reconnects\": " << m_reconnectCount
                << ",\n  \"masters\": " << m_busHandler->getMasterCount()
                << ",\n  \"messages\": " << m_messages->size()
-               << ",\n  \"lastup\": " << static_cast<unsigned>(maxLastUp);
-      if (withDefinition && since <= 0) {
-        *ostream << ",\n  \"types\": [";
-        DataTypeList::getInstance()->dump(verbosity, true, ostream);
-        *ostream << "\n  ]";
-      }
-      *ostream << "\n }"
+               << ",\n  \"lastup\": " << static_cast<unsigned>(maxLastUp)
+               << "\n }"
                << "\n}";
       type = 6;
     }
@@ -2213,6 +2208,16 @@ result_t MainLoop::executeGet(const vector<string>& args, bool* connected, ostri
     return formatHttpResult(ret, type, ostream);
   }  // request for "/data..."
 
+  if (uri == "/datatypes") {
+    *ostream << "[";
+    OutputFormat verbosity = OF_NAMES|OF_JSON|OF_ALL_ATTRS;
+    DataTypeList::getInstance()->dump(verbosity, true, ostream);
+    *ostream << "\n]";
+    type = 6;
+    *connected = false;
+    return formatHttpResult(ret, type, ostream);
+  }
+
   if (uri.length() < 1 || uri[0] != '/' || uri.find("//") != string::npos || uri.find("..") != string::npos) {
     ret = RESULT_ERR_INVALID_ARG;
   } else {
diff --git a/src/lib/ebus/datatype.cpp b/src/lib/ebus/datatype.cpp
index 1bcb6886..697aac3a 100755
--- a/src/lib/ebus/datatype.cpp
+++ b/src/lib/ebus/datatype.cpp
@@ -1125,7 +1125,7 @@ void DataTypeList::dump(OutputFormat outputFormat, bool appendDivisor, ostream*
       continue;
     }
     if (json) {
-      *output << sep << "    {";
+      *output << sep << "  {";
     }
     if ((dataType->getBitCount() % 8) != 0) {
       dataType->dump(outputFormat, dataType->getBitCount(), appendDivisor, output);