diff --git a/dhp-common/src/main/java/eu/dnetlib/dhp/common/Constants.java b/dhp-common/src/main/java/eu/dnetlib/dhp/common/Constants.java
index 108edad47..f8d8e6684 100644
--- a/dhp-common/src/main/java/eu/dnetlib/dhp/common/Constants.java
+++ b/dhp-common/src/main/java/eu/dnetlib/dhp/common/Constants.java
@@ -49,4 +49,9 @@ public class Constants {
 	public static final String CONTENT_INVALIDRECORDS = "InvalidRecords";
 	public static final String CONTENT_TRANSFORMEDRECORDS = "transformedItems";
 
+    // IETF Draft and used by Repositories like ZENODO , not included in APACHE HTTP java packages
+	// see https://ietf-wg-httpapi.github.io/ratelimit-headers/draft-ietf-httpapi-ratelimit-headers.html
+	public static final String HTTPHEADER_IETF_DRAFT_RATELIMIT_LIMIT = "X-RateLimit-Limit";
+	public static final String HTTPHEADER_IETF_DRAFT_RATELIMIT_REMAINING = "X-RateLimit-Remaining";
+	public static final String HTTPHEADER_IETF_DRAFT_RATELIMIT_RESET = "X-RateLimit-Reset";
 }
diff --git a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/HttpConnector2.java b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/HttpConnector2.java
index a84b26955..b745584ee 100644
--- a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/HttpConnector2.java
+++ b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/HttpConnector2.java
@@ -20,7 +20,7 @@ import eu.dnetlib.dhp.aggregation.common.AggregatorReport;
 /**
  * Migrated from https://svn.driver.research-infrastructures.eu/driver/dnet45/modules/dnet-modular-collector-service/trunk/src/main/java/eu/dnetlib/data/collector/plugins/HttpConnector.java
  *
- * @author jochen, michele, andrea, alessia, claudio
+ * @author jochen, michele, andrea, alessia, claudio, andreas
  */
 public class HttpConnector2 {
 
@@ -112,6 +112,17 @@ public class HttpConnector2 {
 			}
 
 			int retryAfter = obtainRetryAfter(urlConn.getHeaderFields());
+			String rateLimit = urlConn.getHeaderField(eu.dnetlib.dhp.common.Constants.HTTPHEADER_IETF_DRAFT_RATELIMIT_LIMIT);
+			String rateRemaining = urlConn.getHeaderField(eu.dnetlib.dhp.common.Constants.HTTPHEADER_IETF_DRAFT_RATELIMIT_REMAINING);
+
+			if((rateLimit != null) && (rateRemaining != null) && ( Integer.parseInt(rateRemaining) < 2)) {
+				if (retryAfter > 0) {
+					backoffAndSleep(retryAfter);
+				} else {
+					backoffAndSleep(1000);
+				} 
+			}
+
 			if (is2xx(urlConn.getResponseCode())) {
 				input = urlConn.getInputStream();
 				responseType = urlConn.getContentType();
diff --git a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiCollectorPlugin.java b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiCollectorPlugin.java
index 67fd352a3..5434bed1b 100644
--- a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiCollectorPlugin.java
+++ b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiCollectorPlugin.java
@@ -62,12 +62,14 @@ public class OaiCollectorPlugin implements CollectorPlugin {
 			throw new CollectorException("Param 'mdFormat' is null or empty");
 		}
 
-		if (fromDate != null && !fromDate.matches("\\d{4}-\\d{2}-\\d{2}") && !fromDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z")) {
-			throw new CollectorException("Invalid date (YYYY-MM-DD): " + fromDate);
+		if (fromDate != null && !fromDate.matches("\\d{4}-\\d{2}-\\d{2}")
+			&& !fromDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z")) {
+			throw new CollectorException("Invalid date (YYYY-MM-DD or YYYY-MM-DDT00:00:00Z): " + fromDate);
 		}
 
-		if (untilDate != null && !untilDate.matches("\\d{4}-\\d{2}-\\d{2}") && !untilDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z")) {
-			throw new CollectorException("Invalid date (YYYY-MM-DD): " + untilDate);
+		if (untilDate != null && !untilDate.matches("\\d{4}-\\d{2}-\\d{2}")
+			&& !untilDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z")) {
+			throw new CollectorException("Invalid date (YYYY-MM-DD or YYYY-MM-DDT00:00:00Z): " + untilDate);
 		}
 
 		final Iterator<Iterator<String>> iters = sets
diff --git a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiIterator.java b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiIterator.java
index c044e02db..392311765 100644
--- a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiIterator.java
+++ b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiIterator.java
@@ -107,10 +107,12 @@ public class OaiIterator implements Iterator<String> {
 			if (set != null && !set.isEmpty()) {
 				url += "&set=" + URLEncoder.encode(set, "UTF-8");
 			}
-			if (fromDate != null && (fromDate.matches("\\d{4}-\\d{2}-\\d{2}") || fromDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z"))) {
+			if (fromDate != null && (fromDate.matches("\\d{4}-\\d{2}-\\d{2}")
+				|| fromDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z"))) {
 				url += "&from=" + URLEncoder.encode(fromDate, "UTF-8");
 			}
-			if (untilDate != null && (untilDate.matches("\\d{4}-\\d{2}-\\d{2}") || untilDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z"))) {
+			if (untilDate != null && (untilDate.matches("\\d{4}-\\d{2}-\\d{2}")
+				|| untilDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z"))) {
 				url += "&until=" + URLEncoder.encode(untilDate, "UTF-8");
 			}
 			log.info("Start harvesting using url: " + url);