diff --git a/contrib/html/openapi.yaml b/contrib/html/openapi.yaml
index f8fbd219c..26ec93a57 100644
--- a/contrib/html/openapi.yaml
+++ b/contrib/html/openapi.yaml
@@ -2,7 +2,7 @@ openapi: 3.1.0
 info:
   title: ebusd-http
   description: The API that ebusd provides on HTTP port.
-  version: "23.2"
+  version: "23.3"
 servers:
   - url: http://127.0.0.1:8080/
 paths:
@@ -145,6 +145,50 @@ paths:
         500:
           description: General error.
           content: { }
+  /templates:
+    get:
+      summary: Get all known field templates for the root.
+      responses:
+        200:
+          description: Success.
+          content:
+            application/json;charset=utf-8:
+              schema:
+                $ref: '#/components/schemas/Templates'
+        400:
+          description: Invalid request parameters.
+          content: { }
+        403:
+          description: User not authorized.
+          content: { }
+        500:
+          description: General error.
+          content: { }
+  /templates/{path}:
+    get:
+      summary: Get all known field templates for the path.
+      parameters:
+        - name: path
+          in: path
+          required: true
+          schema:
+            type: string
+      responses:
+        200:
+          description: Success.
+          content:
+            application/json;charset=utf-8:
+              schema:
+                $ref: '#/components/schemas/Templates'
+        400:
+          description: Invalid request parameters.
+          content: { }
+        403:
+          description: User not authorized.
+          content: { }
+        500:
+          description: General error.
+          content: { }
   /raw:
     get:
       summary: Retrieve raw data from grabbed and/or decoded messages.
@@ -392,8 +436,12 @@ components:
           type: integer
           minimum: 0
         condition:
-          type: string
-          description: the condition string in case of a conditional message (only with full).
+          description: the condition(s) in case of a conditional message (only with full).
+          oneOf:
+            - $ref: '#/components/schemas/Condition'
+            - type: array
+              items:
+                $ref: '#/components/schemas/Condition'
         lastup:
           $ref: '#/components/schemas/Seconds'
           description: the time in UTC seconds of the last update of the message (0
@@ -407,8 +455,12 @@ components:
           description: destination master or slave address.
           example: 8
         id:
-          $ref: '#/components/schemas/Symbols'
-          description: the message ID composed of PBSB and further master data bytes (only with def).
+          description: the message ID composed of PBSB and further master data bytes (only with def), or an array thereof in case of a chained message.
+          oneOf:
+            - $ref: '#/components/schemas/Symbols'
+            - type: array
+              items:
+                $ref: '#/components/schemas/Symbols'
         comment:
           type: string
           description: the message comment (only with verbose).
@@ -465,10 +517,10 @@ components:
         - type: string
         - type: number
       nullable: true
-    FieldDef:
+    FieldTemplate:
+      description: a single field template.
       required:
         - name
-        - slave
         - type
         - isbits
         - length
@@ -477,9 +529,6 @@ components:
         name:
           type: string
           description: the field name.
-        slave:
-          type: boolean
-          description: whether the field is part of the slave data.
         type:
           type: string
           description: the field type.
@@ -513,6 +562,66 @@ components:
         comment:
           type: string
           description: the field comment.
+    FieldDef:
+      description: a single field definition.
+      allOf:
+        - $ref: '#/components/schemas/FieldTemplate'
+        - type: object
+          required:
+            - slave
+          properties:
+            slave:
+              type: boolean
+              description: whether the field is part of the slave data.
+    Templates:
+      type: array
+      description: list of known field templates.
+      items:
+        oneOf:
+          - $ref: '#/components/schemas/FieldTemplate'
+          - type: object
+            required:
+              - name
+              - sequence
+            properties:
+              name:
+                type: string
+                description: the template set name.
+              sequence:
+                type: array
+                description: the sequence of fields.
+                items:
+                  $ref: '#/components/schemas/FieldTemplate'
+    Condition:
+      description: a single condition.
+      required:
+        - name
+        - message
+      properties:
+        name:
+          type: string
+          description: name of the condition.
+        message:
+          type: string
+          description: name of the referenced message.
+        circuit:
+          type: string
+          description: name of the referenced circuit.
+        zz:
+          maximum: 255
+          minimum: 0
+          type: integer
+          description: the circuit slave address.
+        field:
+          type: string
+          description: the field name in the referenced message.
+        value:
+          type: array
+          description: the value ranges for the condition.
+          items:
+            oneOf:
+              - type: number
+              - type: string
     DataType:
       description: a known field data type.
       type: object
diff --git a/src/ebusd/main.cpp b/src/ebusd/main.cpp
index f78270f65..5995c8ee3 100644
--- a/src/ebusd/main.cpp
+++ b/src/ebusd/main.cpp
@@ -352,7 +352,14 @@ int main(int argc, char* argv[], char* envp[]) {
       } else {
         logNotice(lf_main, "configuration dump:");
       }
+      *out << "{\"datatypes\":[";
+      DataTypeList::getInstance()->dump(s_opt.dumpConfig, true, out);
+      *out << "],\"templates\":[";
+      const auto tmpl = s_scanHelper->getTemplates("");
+      tmpl->dump(s_opt.dumpConfig, out);
+      *out << "],\"messages\":";
       s_messageMap->dump(true, s_opt.dumpConfig, out);
+      *out << "}";
       if (fout.is_open()) {
         fout.close();
       }
diff --git a/src/ebusd/mainloop.cpp b/src/ebusd/mainloop.cpp
index 3d35a3765..5da4dbab8 100644
--- a/src/ebusd/mainloop.cpp
+++ b/src/ebusd/mainloop.cpp
@@ -2254,6 +2254,18 @@ result_t MainLoop::executeGet(const vector<string>& args, bool* connected, ostri
     return formatHttpResult(ret, type, ostream);
   }
 
+  if (uri == "/templates" || uri.substr(0, 11) == "/templates/") {
+    *ostream << "[";
+    OutputFormat verbosity = OF_NAMES|OF_JSON|OF_ALL_ATTRS;
+    string name = uri == "/templates" ? "" : uri.substr(11) + "/";
+    const auto tmpl = m_scanHelper->getTemplates(name);
+    tmpl->dump(verbosity, ostream);
+    *ostream << "\n]";
+    type = 6;
+    *connected = false;
+    return formatHttpResult(ret, type, ostream);
+  }
+
   if (uri == "/raw") {
     time_t since = 0, until = 0;
     bool onlyUnknown = false;
diff --git a/src/ebusd/scan.cpp b/src/ebusd/scan.cpp
index 9e337fe05..4309cc42c 100644
--- a/src/ebusd/scan.cpp
+++ b/src/ebusd/scan.cpp
@@ -202,6 +202,19 @@ bool ScanHelper::readTemplates(const string relPath, const string extension, boo
   return false;
 }
 
+void ScanHelper::dumpTemplates(OutputFormat outputFormat, ostream* output) const {
+  bool prependSeparator = false;
+  for (auto it : m_templatesByPath) {
+    if (prependSeparator) {
+      *output << ",";
+    }
+    const auto templates = it.second;
+    if (templates->dump(outputFormat, output)) {
+      prependSeparator = true;
+    }
+  }
+}
+
 result_t ScanHelper::readConfigFiles(const string& relPath, const string& extension, bool recursive,
   string* errorDescription) {
   vector<string> files, dirs;
diff --git a/src/ebusd/scan.h b/src/ebusd/scan.h
index bc8cecf58..6cb4d6c3c 100644
--- a/src/ebusd/scan.h
+++ b/src/ebusd/scan.h
@@ -158,6 +158,13 @@ class ScanHelper : public Resolver {
    */
   bool readTemplates(const string relPath, const string extension, bool available);
 
+  /**
+   * Dump the loaded @a DataFieldTemplates to the output.
+   * @param outputFormat the @a OutputFormat options.
+   * @param output the @a ostream to dump to.
+   */
+  void dumpTemplates(OutputFormat outputFormat, ostream* output) const;
+
   /**
    * Read the configuration files from the specified path.
    * @param relPath the relative path from which to read the files (without trailing "/").
diff --git a/src/lib/ebus/data.cpp b/src/lib/ebus/data.cpp
index 0e9d38bcd..f463ee70e 100644
--- a/src/lib/ebus/data.cpp
+++ b/src/lib/ebus/data.cpp
@@ -482,7 +482,10 @@ void SingleDataField::dumpPrefix(bool prependFieldSeparator, OutputFormat output
     dumpString(prependFieldSeparator, m_name, output);
   }
   if (outputFormat & OF_JSON) {
-    *output << ", \"slave\": " << (m_partType == pt_slaveData ? "true" : "false") << ", ";
+    if (m_partType != pt_any) {
+      *output << ", \"slave\": " << (m_partType == pt_slaveData ? "true" : "false");
+    }
+    *output << ", ";
   } else {
     *output << FIELD_SEPARATOR;
     if (m_partType == pt_masterData) {
@@ -1459,4 +1462,27 @@ const DataField* DataFieldTemplates::get(const string& name) const {
   return ref->second;
 }
 
+bool DataFieldTemplates::dump(OutputFormat outputFormat, ostream* output) const {
+  bool prependFieldSeparator = false;
+  for (const auto &it : m_fieldsByName) {
+    const DataField *dataField = it.second;
+    if (outputFormat & OF_JSON) {
+      if (dataField->isSet()) {
+        if (prependFieldSeparator) {
+          *output << ",\n";  
+        }
+        *output << "{\"name\":\"" << dataField->getName(-1) << "\", \"sequence\": [";
+        dataField->dump(false, outputFormat, output);
+        *output << "]}";
+      } else {
+        dataField->dump(prependFieldSeparator, outputFormat, output);
+      }
+    } else {
+      dataField->dump(prependFieldSeparator, outputFormat, output);
+    }
+    prependFieldSeparator = true;
+  }
+  return !prependFieldSeparator;
+}
+
 }  // namespace ebusd
diff --git a/src/lib/ebus/data.h b/src/lib/ebus/data.h
index f205509a8..810c34884 100755
--- a/src/lib/ebus/data.h
+++ b/src/lib/ebus/data.h
@@ -836,6 +836,14 @@ class DataFieldTemplates : public MappedFileReader {
    */
   const DataField* get(const string& name) const;
 
+  /**
+   * Dump the templates to the output.
+   * @param outputFormat the @a OutputFormat options.
+   * @param output the @a ostream to dump to.
+   * @return true when a template was written to the output.
+   */
+  bool dump(OutputFormat outputFormat, ostream* output) const;
+
 
  private:
   /** the known template @a DataField instances by name. */
diff --git a/src/lib/ebus/message.cpp b/src/lib/ebus/message.cpp
index 54a634fa5..1c77a7fd0 100644
--- a/src/lib/ebus/message.cpp
+++ b/src/lib/ebus/message.cpp
@@ -970,9 +970,8 @@ void Message::decodeJson(bool leadingSeparator, bool appendDirectionCondition, b
       *output << ",\n    \"pollprio\": " << setw(0) << dec << getPollPriority();
     }
     if (isConditional()) {
-      *output << ",\n    \"condition\": \"";
-      m_condition->dump(false, output);
-      *output << "\"";
+      *output << ",\n    \"condition\": ";
+      m_condition->dumpJson(output);
     }
   }
   if (withData) {
@@ -985,13 +984,8 @@ void Message::decodeJson(bool leadingSeparator, bool appendDirectionCondition, b
     }
     *output << ",\n    \"zz\": " << dec << static_cast<unsigned>(m_dstAddress);
     if (withDefinition) {
-      *output << ",\n    \"id\": [" << dec;
-      for (auto it = m_id.begin(); it < m_id.end(); it++) {
-        if (it > m_id.begin()) {
-          *output << ", ";
-        }
-        *output << dec << static_cast<unsigned>(*it);
-      }
+      *output << ",\n    \"id\": [";
+      dumpIdsJson(output);
       *output << "]";
     }
     appendAttributes(outputFormat, output);
@@ -1022,6 +1016,15 @@ void Message::decodeJson(bool leadingSeparator, bool appendDirectionCondition, b
   *output << "\n   }";
 }
 
+void Message::dumpIdsJson(ostringstream* output) const {
+  for (auto it = m_id.begin(); it < m_id.end(); it++) {
+    if (it > m_id.begin()) {
+      *output << ", ";
+    }
+    *output << dec << static_cast<unsigned>(*it);
+  }
+}
+
 bool Message::setDataHandlerState(int state, bool addBits) {
   if (addBits ? state == (m_dataHandlerState&state) : state == m_dataHandlerState) {
     return false;
@@ -1296,6 +1299,22 @@ void ChainedMessage::dumpField(const string& fieldName, bool withConditions, Out
   }
 }
 
+void ChainedMessage::dumpIdsJson(ostringstream* output) const {
+  for (auto idsit = m_ids.begin(); idsit < m_ids.end(); idsit++) {
+    if (idsit > m_ids.begin()) {
+      *output << ",";
+    }
+    *output << "[";
+    for (auto it = (*idsit).begin(); it < (*idsit).end(); it++) {
+      if (it > (*idsit).begin()) {
+        *output << ", ";
+      }
+      *output << dec << static_cast<unsigned>(*it);
+    }
+    *output << "]";
+  }
+}
+
 
 /**
  * Get the first available @a Message from the list.
@@ -1527,6 +1546,27 @@ void SimpleCondition::dump(bool matched, ostream* output) const {
   }
 }
 
+void SimpleCondition::dumpJson(ostream* output) const {
+  *output << "{\"name\": \"" << m_refName << "\"";
+  if (!m_circuit.empty()) {
+    *output << ",\"circuit\":\"" << m_circuit << "\"";
+  }
+  *output << ",\"message\":\"" << (m_name.empty() ? "scan" : m_name) << "\"";
+  if (m_dstAddress != SYN) {
+    *output << ",\"zz\":" << dec << static_cast<unsigned>(m_dstAddress);
+  }
+  if (!m_field.empty()) {
+    *output << ",\"field\":\"" << m_field << "\"";
+  }
+  if (m_hasValues) {
+    *output << ",\"value\":[";
+    dumpValuesJson(output);
+    *output << "]";
+  }
+  *output << "}";
+}
+
+
 CombinedCondition* SimpleCondition::combineAnd(Condition* other) {
   CombinedCondition* ret = new CombinedCondition();
   return ret->combineAnd(this)->combineAnd(other);
@@ -1625,6 +1665,17 @@ bool SimpleNumericCondition::checkValue(const Message* message, const string& fi
   return false;
 }
 
+void SimpleNumericCondition::dumpValuesJson(ostream* output) const {
+  bool first = true;
+  for (const auto value : m_valueRanges) {
+    if (!first) {
+      *output << ",";
+    }
+    *output << static_cast<unsigned>(value);
+    first = false;
+  }
+}
+
 
 bool SimpleStringCondition::checkValue(const Message* message, const string& field) {
   ostringstream output;
@@ -1641,6 +1692,17 @@ bool SimpleStringCondition::checkValue(const Message* message, const string& fie
   return false;
 }
 
+void SimpleStringCondition::dumpValuesJson(ostream* output) const {
+  bool first = true;
+  for (const auto value : m_values) {
+    if (!first) {
+      *output << ",";
+    }
+    *output << "\"" << value << "\"";
+    first = false;
+  }
+}
+
 
 void CombinedCondition::dump(bool matched, ostream* output) const {
   for (const auto condition : m_conditions) {
@@ -1648,6 +1710,19 @@ void CombinedCondition::dump(bool matched, ostream* output) const {
   }
 }
 
+void CombinedCondition::dumpJson(ostream* output) const {
+  *output << "[";
+  bool first = true;
+  for (const auto condition : m_conditions) {
+    if (!first) {
+      *output << ",";
+    }
+    condition->dumpJson(output);
+    first = false;
+  }
+  *output << "]";
+}
+
 result_t CombinedCondition::resolve(void (*readMessageFunc)(Message* message), MessageMap* messages,
     ostringstream* errorMessage) {
   for (const auto condition : m_conditions) {
@@ -2817,7 +2892,7 @@ void MessageMap::dump(bool withConditions, OutputFormat outputFormat, ostream* o
   bool first = true;
   bool isJson = (outputFormat & OF_JSON) != 0;
   if (isJson) {
-    *output << (m_addAll ? "[" : "}");
+    *output << (m_addAll ? "[" : "{");
   } else {
     Message::dumpHeader(nullptr, output);
   }
diff --git a/src/lib/ebus/message.h b/src/lib/ebus/message.h
index fcd60ac9b..7d314670f 100644
--- a/src/lib/ebus/message.h
+++ b/src/lib/ebus/message.h
@@ -601,6 +601,12 @@ class Message : public AttributedItem {
                           OutputFormat outputFormat, ostringstream* output) const;
 
  protected:
+  /**
+   * Dump the ID(s) to the output in JSON format.
+   * @param output the @a ostringstream to append to.
+  */
+  virtual void dumpIdsJson(ostringstream* output) const;
+
   /** the source filename. */
   const string m_filename;
 
@@ -748,6 +754,8 @@ class ChainedMessage : public Message {
   result_t prepareMasterPart(size_t index, const char separator, istringstream* input,
       MasterSymbolString* master) override;
 
+  // @copydoc
+  void dumpIdsJson(ostringstream* output) const override;
 
  public:
   // @copydoc
@@ -884,6 +892,18 @@ class Condition {
    */
   virtual void dump(bool matched, ostream* output) const = 0;
 
+  /**
+   * Write the condition definition in JSON to the @a ostream.
+   * @param output the @a ostream to append to.
+   */
+  virtual void dumpJson(ostream* output) const = 0;
+
+  /**
+   * Write the values part of the condition definition in JSON to the @a ostream.
+   * @param output the @a ostream to append to.
+   */
+  virtual void dumpValuesJson(ostream* output) const { /* empty on top level*/ };
+
   /**
    * Combine this condition with another instance using a logical and.
    * @param other the @a Condition to combine with.
@@ -951,6 +971,9 @@ class SimpleCondition : public Condition {
   // @copydoc
   void dump(bool matched, ostream* output) const override;
 
+  // @copydoc
+  void dumpJson(ostream* output) const override;
+
   // @copydoc
   CombinedCondition* combineAnd(Condition* other) override;
 
@@ -1043,6 +1066,9 @@ class SimpleNumericCondition : public SimpleCondition {
   // @copydoc
   bool checkValue(const Message* message, const string& field) override;
 
+  // @copydoc
+  void dumpValuesJson(ostream* output) const override;
+
 
  private:
   /** the valid value ranges (pairs of from/to inclusive), empty for @a m_message seen check. */
@@ -1084,6 +1110,9 @@ class SimpleStringCondition : public SimpleCondition {
   // @copydoc
   bool checkValue(const Message* message, const string& field) override;
 
+  // @copydoc
+  void dumpValuesJson(ostream* output) const override;
+
 
  private:
   /** the valid values. */
@@ -1110,6 +1139,9 @@ class CombinedCondition : public Condition {
   // @copydoc
   void dump(bool matched, ostream* output) const override;
 
+  // @copydoc
+  void dumpJson(ostream* output) const override;
+
   // @copydoc
   CombinedCondition* combineAnd(Condition* other) override { m_conditions.push_back(other); return this; }