diff --git a/akka-protobuf/src/main/java/akka/protobuf/ByteString.java b/akka-protobuf/src/main/java/akka/protobuf/ByteString.java
index 3f5ae45531..b453331c1e 100644
--- a/akka-protobuf/src/main/java/akka/protobuf/ByteString.java
+++ b/akka-protobuf/src/main/java/akka/protobuf/ByteString.java
@@ -373,7 +373,7 @@ public abstract class ByteString implements Iterable<Byte> {
    * Concatenate the given {@code ByteString} to this one. Short concatenations,
    * of total size smaller than {@link ByteString#CONCATENATE_BY_COPY_SIZE}, are
    * produced by copying the underlying bytes (as per Rope.java, <a
-   * href="http://www.cs.ubc.ca/local/reading/proceedings/spe91-95/spe/vol25/issue12/spe986.pdf">
+   * href="https://www.cs.ubc.ca/local/reading/proceedings/spe91-95/spe/vol25/issue12/spe986.pdf">
    * BAP95 </a>. In general, the concatenate involves no copying.
    *
    * @param other string to concatenate
diff --git a/akka-protobuf/src/main/java/akka/protobuf/RopeByteString.java b/akka-protobuf/src/main/java/akka/protobuf/RopeByteString.java
index 19a02016dd..d76aad6a36 100644
--- a/akka-protobuf/src/main/java/akka/protobuf/RopeByteString.java
+++ b/akka-protobuf/src/main/java/akka/protobuf/RopeByteString.java
@@ -53,7 +53,7 @@ import java.util.Stack;
  * represented as a tree whose leaf nodes are each a {@link LiteralByteString}.
  *
  * <p>Most of the operation here is inspired by the now-famous paper <a
- * href="http://www.cs.ubc.ca/local/reading/proceedings/spe91-95/spe/vol25/issue12/spe986.pdf">
+ * href="https://www.cs.ubc.ca/local/reading/proceedings/spe91-95/spe/vol25/issue12/spe986.pdf">
  * BAP95 </a> Ropes: an Alternative to Strings hans-j. boehm, russ atkinson and
  * michael plass
  *
diff --git a/akka-remote/src/main/scala/akka/remote/PhiAccrualFailureDetector.scala b/akka-remote/src/main/scala/akka/remote/PhiAccrualFailureDetector.scala
index e6a26b1cc8..c36cb40903 100644
--- a/akka-remote/src/main/scala/akka/remote/PhiAccrualFailureDetector.scala
+++ b/akka-remote/src/main/scala/akka/remote/PhiAccrualFailureDetector.scala
@@ -21,7 +21,7 @@ import akka.util.Helpers.ConfigOps
 
 /**
  * Implementation of 'The Phi Accrual Failure Detector' by Hayashibara et al. as defined in their paper:
- * [http://www.jaist.ac.jp/~defago/files/pdf/IS_RR_2004_010.pdf]
+ * [https://oneofus.la/have-emacs-will-hack/files/HDY04.pdf]
  *
  * The suspicion level of failure is given by a value called φ (phi).
  * The basic idea of the φ failure detector is to express the value of φ on a scale that
diff --git a/akka-remote/src/main/scala/akka/remote/artery/LruBoundedCache.scala b/akka-remote/src/main/scala/akka/remote/artery/LruBoundedCache.scala
index 59e8d4832e..4387648453 100644
--- a/akka-remote/src/main/scala/akka/remote/artery/LruBoundedCache.scala
+++ b/akka-remote/src/main/scala/akka/remote/artery/LruBoundedCache.scala
@@ -16,8 +16,8 @@ private[akka] case class CacheStatistics(entries: Int, maxProbeDistance: Int, av
  * INTERNAL API
  *
  * This class is based on a Robin-Hood hashmap
- * (http://www.sebastiansylvan.com/post/robin-hood-hashing-should-be-your-default-hash-table-implementation/)
- * with backshift (http://codecapsule.com/2013/11/17/robin-hood-hashing-backward-shift-deletion/).
+ * (https://www.sebastiansylvan.com/post/robin-hood-hashing-should-be-your-default-hash-table-implementation/)
+ * with backshift (https://codecapsule.com/2013/11/17/robin-hood-hashing-backward-shift-deletion/).
  *
  * The main modification compared to an RH hashmap is that it never grows the map (no rehashes) instead it is allowed
  * to kick out entires that are considered old. The implementation tries to keep the map close to full, only evicting
diff --git a/akka-remote/src/main/scala/akka/remote/artery/compress/TopHeavyHitters.scala b/akka-remote/src/main/scala/akka/remote/artery/compress/TopHeavyHitters.scala
index 129298bd32..bc8d75d169 100644
--- a/akka-remote/src/main/scala/akka/remote/artery/compress/TopHeavyHitters.scala
+++ b/akka-remote/src/main/scala/akka/remote/artery/compress/TopHeavyHitters.scala
@@ -16,7 +16,7 @@ import scala.reflect.ClassTag
  *
  * Keeps a number of specific heavy hitters around in memory.
  *
- * See also Section 5.2 of http://dimacs.rutgers.edu/~graham/pubs/papers/cm-full.pdf
+ * See also Section 5.2 of https://dimacs.rutgers.edu/~graham/pubs/papers/cm-full.pdf
  * for a discussion about the assumptions made and guarantees about the Heavy Hitters made in this model.
  * We assume the Cash Register model in which there are only additions, which simplifies HH detection significantly.
  *