Retrive List of All WorkFlow Rule And Validation Rule Using Metadata

Print List of Workflow or Validation Rule

Create a Class For MetaData Service

public class MetadataService {
    public class ListMetadataQuery {
        public String folder;
        public String type_x;
        private String[] folder_type_info = new String[]{'folder','http://soap.sforce.com/2006/04/metadata',null,'0','1','false'};
        private String[] type_x_type_info = new String[]{'type','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata','true','false'};
        private String[] field_order_type_info = new String[]{'folder','type_x'};
    }
    public class FileProperties {
        public String createdById;
        public String createdByName;
        public DateTime createdDate;
        public String fileName;
        public String fullName;
        public String id;
        public String lastModifiedById;
        public String lastModifiedByName;
        public DateTime lastModifiedDate;
        public String manageableState;
        public String namespacePrefix;
        public String type_x;
        private String[] createdById_type_info = new String[]{'createdById','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] createdByName_type_info = new String[]{'createdByName','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] createdDate_type_info = new String[]{'createdDate','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] fileName_type_info = new String[]{'fileName','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] fullName_type_info = new String[]{'fullName','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] id_type_info = new String[]{'id','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] lastModifiedById_type_info = new String[]{'lastModifiedById','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] lastModifiedByName_type_info = new String[]{'lastModifiedByName','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] lastModifiedDate_type_info = new String[]{'lastModifiedDate','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] manageableState_type_info = new String[]{'manageableState','http://soap.sforce.com/2006/04/metadata',null,'0','1','false'};
        private String[] namespacePrefix_type_info = new String[]{'namespacePrefix','http://soap.sforce.com/2006/04/metadata',null,'0','1','false'};
        private String[] type_x_type_info = new String[]{'type','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata','true','false'};
        private String[] field_order_type_info = new String[]{'createdById','createdByName','createdDate','fileName','fullName','id','lastModifiedById','lastModifiedByName','lastModifiedDate','manageableState','namespacePrefix','type_x'};
    }
    public class SessionHeader_element {
        public String sessionId;
        private String[] sessionId_type_info = new String[]{'sessionId','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata','true','false'};
        private String[] field_order_type_info = new String[]{'sessionId'};
    }
    public class DebuggingInfo_element {
        public String debugLog;
        private String[] debugLog_type_info = new String[]{'debugLog','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata','true','false'};
        private String[] field_order_type_info = new String[]{'debugLog'};
    }
    public class CallOptions_element {
        public String client;
        private String[] client_type_info = new String[]{'client','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata','true','false'};
        private String[] field_order_type_info = new String[]{'client'};
    }
    public class AllOrNoneHeader_element {
        public Boolean allOrNone;
        private String[] allOrNone_type_info = new String[]{'allOrNone','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata','true','false'};
        private String[] field_order_type_info = new String[]{'allOrNone'};
    }
    public class DebuggingHeader_element {
        public MetadataService.LogInfo[] categories;
        public String debugLevel;
        private String[] categories_type_info = new String[]{'categories','http://soap.sforce.com/2006/04/metadata',null,'0','-1','false'};
        private String[] debugLevel_type_info = new String[]{'debugLevel','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata','true','false'};
        private String[] field_order_type_info = new String[]{'categories','debugLevel'};
    }
    public class LogInfo {
        public String category;
        public String level;
        private String[] category_type_info = new String[]{'category','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] level_type_info = new String[]{'level','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata','true','false'};
        private String[] field_order_type_info = new String[]{'category','level'};
    }
    public class listMetadata_element {
        public MetadataService.ListMetadataQuery[] queries;
        public Double asOfVersion;
        private String[] queries_type_info = new String[]{'queries','http://soap.sforce.com/2006/04/metadata',null,'0','-1','false'};
        private String[] asOfVersion_type_info = new String[]{'asOfVersion','http://soap.sforce.com/2006/04/metadata',null,'1','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata','true','false'};
        private String[] field_order_type_info = new String[]{'queries','asOfVersion'};
    }
    public class listMetadataResponse_element {
        public MetadataService.FileProperties[] result;
        private String[] result_type_info = new String[]{'result','http://soap.sforce.com/2006/04/metadata',null,'0','-1','false'};
        private String[] apex_schema_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata','true','false'};
        private String[] field_order_type_info = new String[]{'result'};
    }
    public class MetadataPort {
        public String endpoint_x = URL.getSalesforceBaseUrl().toExternalForm() + '/services/Soap/m/37.0';
        public Map<String,String> inputHttpHeaders_x;
        public Map<String,String> outputHttpHeaders_x;
        public String clientCertName_x;
        public String clientCert_x;
        public String clientCertPasswd_x;
        public Integer timeout_x;
        public MetadataService.SessionHeader_element SessionHeader;
        public MetadataService.DebuggingInfo_element DebuggingInfo;
        public MetadataService.DebuggingHeader_element DebuggingHeader;
        public MetadataService.CallOptions_element CallOptions;
        public MetadataService.AllOrNoneHeader_element AllOrNoneHeader;
        private String SessionHeader_hns = 'SessionHeader=http://soap.sforce.com/2006/04/metadata';
        private String DebuggingInfo_hns = 'DebuggingInfo=http://soap.sforce.com/2006/04/metadata';
        private String DebuggingHeader_hns = 'DebuggingHeader=http://soap.sforce.com/2006/04/metadata';
        private String CallOptions_hns = 'CallOptions=http://soap.sforce.com/2006/04/metadata';
        private String AllOrNoneHeader_hns = 'AllOrNoneHeader=http://soap.sforce.com/2006/04/metadata';
        private String[] ns_map_type_info = new String[]{'http://soap.sforce.com/2006/04/metadata', 'MetadataService'};
        
        public MetadataService.FileProperties[] listMetadata(MetadataService.ListMetadataQuery[] queries,Double asOfVersion) {
            MetadataService.listMetadata_element request_x = new MetadataService.listMetadata_element();
            request_x.queries = queries;
            request_x.asOfVersion = asOfVersion;
            MetadataService.listMetadataResponse_element response_x;
            Map<String, MetadataService.listMetadataResponse_element> response_map_x = new Map<String, MetadataService.listMetadataResponse_element>();
            response_map_x.put('response_x', response_x);
            WebServiceCallout.invoke(
              this,
              request_x,
              response_map_x,
              new String[]{endpoint_x,
              '',
              'http://soap.sforce.com/2006/04/metadata',
              'listMetadata',
              'http://soap.sforce.com/2006/04/metadata',
              'listMetadataResponse',
              'MetadataService.listMetadataResponse_element'}
            );
            response_x = response_map_x.get('response_x');
            return response_x.result;
        }
    }
}

Now Just call following Code in Class or Controller

This one for Validation Rules

MetadataService.MetadataPort service = new MetadataService.MetadataPort();
        service.SessionHeader = new MetadataService.SessionHeader_element();
        service.SessionHeader.sessionId = UserInfo.getSessionId();
        
        List<MetadataService.ListMetadataQuery> queries = new List<MetadataService.ListMetadataQuery>();    
        MetadataService.ListMetadataQuery queryLayout = new MetadataService.ListMetadataQuery();
        queryLayout.folder = '';
        queryLayout.type_x = 'ValidationRule';
        queries.add(queryLayout);    
        MetadataService.FileProperties[] fileProperties = service.listMetadata(queries, 25);
          if(fileProperties!=null)
            {
              for(MetadataService.FileProperties fileProperty : fileProperties)
              {
                  System.Debug(fileProperty.fullName); 
              }
            }

Similarly for WorkFlow Rules

queryLayout1.type_x = 'WorkflowRule';

Note : Don't Forget to add remote setting for your org url.