diff --git a/lisp/org-element.el b/lisp/org-element.el
index 9b6f67ab1..ec00fbd4c 100644
--- a/lisp/org-element.el
+++ b/lisp/org-element.el
@@ -3090,7 +3090,7 @@ Assume point is at the beginning of the link."
 	(setq path (match-string-no-properties 1))
 	(setq contents-begin (match-beginning 1))
 	(setq contents-end (match-end 1)))
-       ;; Type 2: Standard link, i.e. [[http://orgmode.org][homepage]]
+       ;; Type 2: Standard link, i.e. [[https://orgmode.org][homepage]]
        ((looking-at org-bracket-link-regexp)
 	(setq format 'bracket)
 	(setq contents-begin (match-beginning 3))
@@ -3139,14 +3139,14 @@ Assume point is at the beginning of the link."
 	 (t
 	  (setq type "fuzzy")
 	  (setq path raw-link))))
-       ;; Type 3: Plain link, e.g., http://orgmode.org
+       ;; Type 3: Plain link, e.g., https://orgmode.org
        ((looking-at org-plain-link-re)
 	(setq format 'plain)
 	(setq raw-link (match-string-no-properties 0))
 	(setq type (match-string-no-properties 1))
 	(setq link-end (match-end 0))
 	(setq path (match-string-no-properties 2)))
-       ;; Type 4: Angular link, e.g., <http://orgmode.org>.  Unlike to
+       ;; Type 4: Angular link, e.g., <https://orgmode.org>.  Unlike to
        ;; bracket links, follow RFC 3986 and remove any extra
        ;; whitespace in URI.
        ((looking-at org-angle-link-re)
diff --git a/lisp/org-protocol.el b/lisp/org-protocol.el
index 3cbbc78dc..a0e2e4228 100644
--- a/lisp/org-protocol.el
+++ b/lisp/org-protocol.el
@@ -184,10 +184,10 @@ Possible properties are:
 Example:
 
    (setq org-protocol-project-alist
-       \\='((\"http://orgmode.org/worg/\"
+       \\='((\"https://orgmode.org/worg/\"
           :online-suffix \".php\"
           :working-suffix \".org\"
-          :base-url \"http://orgmode.org/worg/\"
+          :base-url \"https://orgmode.org/worg/\"
           :working-directory \"/home/user/org/Worg/\")
          (\"http://localhost/org-notes/\"
           :online-suffix \".html\"
@@ -688,7 +688,7 @@ the cdr of an element in `org-publish-project-alist', reuse
   (let ((working-dir (expand-file-name
 		      (or (plist-get project-plist :base-directory)
 			  default-directory)))
-        (base-url "http://orgmode.org/worg/")
+        (base-url "https://orgmode.org/worg/")
         (strip-suffix (or (plist-get project-plist :html-extension) ".html"))
         (working-suffix (if (plist-get project-plist :base-extension)
                             (concat "." (plist-get project-plist :base-extension))
diff --git a/testing/lisp/test-ob-tangle.el b/testing/lisp/test-ob-tangle.el
index 73b75323e..560cc6c56 100644
--- a/testing/lisp/test-ob-tangle.el
+++ b/testing/lisp/test-ob-tangle.el
@@ -82,9 +82,9 @@
   "Test commenting of links at left margin."
   (should
    (string-match
-    (regexp-quote "# [[http://orgmode.org][Org mode]]")
+    (regexp-quote "# [[https://orgmode.org][Org mode]]")
     (org-test-with-temp-text-in-file
-        "[[http://orgmode.org][Org mode]]
+        "[[https://orgmode.org][Org mode]]
 #+header: :comments org :tangle \"test-ob-tangle.sh\"
 #+begin_src sh
 echo 1
diff --git a/testing/lisp/test-org-clock.el b/testing/lisp/test-org-clock.el
index 1388c50df..6300be856 100644
--- a/testing/lisp/test-org-clock.el
+++ b/testing/lisp/test-org-clock.el
@@ -640,20 +640,20 @@ CLOCK: [2016-12-27 Wed 13:09]--[2016-12-28 Wed 15:09] => 26:00"
 |--------------+---------|
 | *Total time* | *26:00* |
 |--------------+---------|
-| [[Foo %5B%5Bhttp://orgmode.org%5D%5BOrg mode%5D%5D][Foo Org mode]] | 26:00   |"
+| [[Foo %5B%5Bhttps://orgmode.org%5D%5BOrg mode%5D%5D][Foo Org mode]] | 26:00   |"
     (org-test-with-temp-text
-	"* Foo [[http://orgmode.org][Org mode]]
+	"* Foo [[https://orgmode.org][Org mode]]
 CLOCK: [2016-12-27 Wed 13:09]--[2016-12-28 Wed 15:09] => 26:00"
       (test-org-clock-clocktable-contents ":link t"))))
   (should
    (equal
-    "| Headline               | Time    |
-|------------------------+---------|
-| *Total time*           | *26:00* |
-|------------------------+---------|
-| [[Foo %5B%5Bhttp://orgmode.org%5D%5D][Foo http://orgmode.org]] | 26:00   |"
+    "| Headline                | Time    |
+|-------------------------+---------|
+| *Total time*            | *26:00* |
+|-------------------------+---------|
+| [[Foo %5B%5Bhttps://orgmode.org%5D%5D][Foo https://orgmode.org]] | 26:00   |"
     (org-test-with-temp-text
-	"* Foo [[http://orgmode.org]]
+	"* Foo [[https://orgmode.org]]
 CLOCK: [2016-12-27 Wed 13:09]--[2016-12-28 Wed 15:09] => 26:00"
       (test-org-clock-clocktable-contents ":link t")))))
 
diff --git a/testing/lisp/test-org-colview.el b/testing/lisp/test-org-colview.el
index 721aa87fe..fd00a2dde 100644
--- a/testing/lisp/test-org-colview.el
+++ b/testing/lisp/test-org-colview.el
@@ -143,7 +143,7 @@
   (should
    (equal
     '("* [123]" . 7)
-    (org-test-with-temp-text "* [[http://orgmode.org][123]]"
+    (org-test-with-temp-text "* [[https://orgmode.org][123]]"
       (let ((org-columns-default-format "%ITEM")) (org-columns))
       (cons (get-char-property (point) 'org-columns-value-modified)
 	    (aref org-columns-current-maxwidths 0)))))
diff --git a/testing/lisp/test-org-element.el b/testing/lisp/test-org-element.el
index b17e86b8b..533a317d4 100644
--- a/testing/lisp/test-org-element.el
+++ b/testing/lisp/test-org-element.el
@@ -1722,14 +1722,14 @@ e^{i\\pi}+1=0
   (should
    (equal
     '("Orgmode.org")
-    (org-test-with-temp-text "[[http://orgmode.org][Orgmode.org]]"
+    (org-test-with-temp-text "[[https://orgmode.org][Orgmode.org]]"
       (org-element-contents
        (org-element-map (org-element-parse-buffer) 'link 'identity nil t)))))
   ;; ... without description.
   (should
    (equal
-    "http"
-    (org-test-with-temp-text "[[http://orgmode.org]]"
+    "https"
+    (org-test-with-temp-text "[[https://orgmode.org]]"
       (org-element-property
        :type
        (org-element-map (org-element-parse-buffer) 'link 'identity nil t)))))
@@ -1738,7 +1738,7 @@ e^{i\\pi}+1=0
    (equal
     "//orgmode.org/worg"
     (org-test-with-temp-text "[[Org:worg]]"
-      (let ((org-link-abbrev-alist '(("Org" . "http://orgmode.org/"))))
+      (let ((org-link-abbrev-alist '(("Org" . "https://orgmode.org/"))))
 	(org-element-property
 	 :path
 	 (org-element-map (org-element-parse-buffer) 'link 'identity nil t))))))
@@ -1746,7 +1746,7 @@ e^{i\\pi}+1=0
   (should
    (equal
     "127.0.0.1"
-    (org-test-with-temp-text "[[http://orgmode.org]]"
+    (org-test-with-temp-text "[[https://orgmode.org]]"
       (let ((org-link-translation-function
 	     (lambda (type _) (cons type "127.0.0.1"))))
 	(org-element-property
@@ -1819,30 +1819,30 @@ e^{i\\pi}+1=0
 	    (org-element-property :path (org-element-context)))))
   ;; Plain link.
   (should
-   (org-test-with-temp-text "A link: http://orgmode.org"
+   (org-test-with-temp-text "A link: https://orgmode.org"
      (org-element-map (org-element-parse-buffer) 'link 'identity)))
   ;; Angular link.  Follow RFC 3986.
   (should
    (eq 'link
-       (org-test-with-temp-text "A link: <point><http://orgmode.org>"
+       (org-test-with-temp-text "A link: <point><https://orgmode.org>"
 	 (org-element-type (org-element-context)))))
   (should
    (equal "//orgmode.org"
-	  (org-test-with-temp-text "A link: <point><http://orgmode\n.org>"
+	  (org-test-with-temp-text "A link: <point><https://orgmode\n.org>"
 	    (org-element-property :path (org-element-context)))))
   ;; Link abbreviation.
   (should
-   (equal "http"
+   (equal "https"
 	  (org-test-with-temp-text
-	      "#+LINK: orgmode http://www.orgmode.org/\n[[orgmode:#docs]]"
+	      "#+LINK: orgmode https://www.orgmode.org/\n[[orgmode:#docs]]"
 	    (progn (org-mode-restart)
 		   (goto-char (1- (point-max)))
 		   (org-element-property :type (org-element-context))))))
   ;; Link abbreviation in a secondary string.
   (should
-   (equal "http"
+   (equal "https"
 	  (org-test-with-temp-text
-	      "#+LINK: orgmode http://www.orgmode.org/\n* H [[orgmode:#docs]]"
+	      "#+LINK: orgmode https://www.orgmode.org/\n* H [[orgmode:#docs]]"
 	    (progn (org-mode-restart)
 		   (org-element-map (org-element-parse-buffer) 'link
 		     (lambda (link) (org-element-property :type link))
@@ -3139,15 +3139,15 @@ DEADLINE: <2012-03-29 thu.> SCHEDULED: <2012-03-29 thu.> CLOSED: [2012-03-29 thu
 		   (org-test-parse-and-interpret "a radio-target"))
 		 "a radio-target\n"))
   ;; Links without description.
-  (should (equal (org-test-parse-and-interpret "[[http://orgmode.org]]")
-		 "[[http://orgmode.org]]\n"))
+  (should (equal (org-test-parse-and-interpret "[[https://orgmode.org]]")
+		 "[[https://orgmode.org]]\n"))
   ;; Links with a description, even one containing a link.
   (should (equal (org-test-parse-and-interpret
-		  "[[http://orgmode.org][Org mode]]")
-		 "[[http://orgmode.org][Org mode]]\n"))
+		  "[[https://orgmode.org][Org mode]]")
+		 "[[https://orgmode.org][Org mode]]\n"))
   (should (equal (org-test-parse-and-interpret
-		  "[[http://orgmode.org][http://orgmode.org]]")
-		 "[[http://orgmode.org][http://orgmode.org]]\n"))
+		  "[[https://orgmode.org][https://orgmode.org]]")
+		 "[[https://orgmode.org][https://orgmode.org]]\n"))
   ;; File links.
   (should
    (equal (org-test-parse-and-interpret "[[file+emacs:todo.org]]")
@@ -3162,11 +3162,11 @@ DEADLINE: <2012-03-29 thu.> SCHEDULED: <2012-03-29 thu.> CLOSED: [2012-03-29 thu
   ;; Code-ref links.
   (should (equal (org-test-parse-and-interpret "[[(ref)]]") "[[(ref)]]\n"))
   ;; Plain links.
-  (should (equal (org-test-parse-and-interpret "http://orgmode.org")
-		 "http://orgmode.org\n"))
+  (should (equal (org-test-parse-and-interpret "https://orgmode.org")
+		 "https://orgmode.org\n"))
   ;; Angular links.
-  (should (equal (org-test-parse-and-interpret "<http://orgmode.org>")
-		 "<http://orgmode.org>\n"))
+  (should (equal (org-test-parse-and-interpret "<https://orgmode.org>")
+		 "<https://orgmode.org>\n"))
   ;; Pathological case: link with a %-sign in description.
   (should (equal (org-test-parse-and-interpret "[[file://path][%s]]")
 		 "[[file://path][%s]]\n")))
@@ -3589,7 +3589,7 @@ Text
   ;; Special case: objects in inline footnotes.
   (should
    (eq 'link
-       (org-test-with-temp-text "[fn::[[<point>http://orgmode.org]]]"
+       (org-test-with-temp-text "[fn::[[<point>https://orgmode.org]]]"
 	 (org-element-type (org-element-context)))))
   ;; Special case: tags looking like a link.
   (should-not
diff --git a/testing/lisp/test-org-feed.el b/testing/lisp/test-org-feed.el
index d28abb990..52689673c 100644
--- a/testing/lisp/test-org-feed.el
+++ b/testing/lisp/test-org-feed.el
@@ -37,8 +37,8 @@
 	  (org-feed-format-entry nil "%(concat \"success\" \"!\")" nil)))
   ;; %a placeholder.
   (should
-   (equal "[[http://orgmode.org]]\n"
-	  (org-feed-format-entry '(:link "http://orgmode.org") "%a" nil)))
+   (equal "[[https://orgmode.org]]\n"
+	  (org-feed-format-entry '(:link "https://orgmode.org") "%a" nil)))
   ;; %t and %T placeholders.
   (should
    (equal (format-time-string (org-time-stamp-format nil nil))
diff --git a/testing/lisp/test-org-footnote.el b/testing/lisp/test-org-footnote.el
index 78ff459d3..f5877a861 100644
--- a/testing/lisp/test-org-footnote.el
+++ b/testing/lisp/test-org-footnote.el
@@ -74,7 +74,7 @@
       (let ((org-footnote-auto-label t)) (org-footnote-new))
       (buffer-string))))
   (should-error
-   (org-test-with-temp-text " [[http://orgmode.org][Org mode<point>]]"
+   (org-test-with-temp-text " [[https://orgmode.org][Org mode<point>]]"
      (org-footnote-new)))
   ;; Allow new footnotes in blank lines after an element or white
   ;; spaces after an object.
diff --git a/testing/lisp/test-org.el b/testing/lisp/test-org.el
index 9a51c5440..cb21cda47 100644
--- a/testing/lisp/test-org.el
+++ b/testing/lisp/test-org.el
@@ -1801,12 +1801,12 @@
   (should
    (equal '("Org")
 	  (org-test-with-temp-text
-	      "* [[http://orgmode.org][Org]]\n** S<point>"
+	      "* [[https://orgmode.org][Org]]\n** S<point>"
 	    (org-get-outline-path))))
   (should
-   (equal '("http://orgmode.org")
+   (equal '("https://orgmode.org")
 	  (org-test-with-temp-text
-	      "* [[http://orgmode.org]]\n** S<point>"
+	      "* [[https://orgmode.org]]\n** S<point>"
 	    (org-get-outline-path))))
   ;; When WITH-SELF is non-nil, include current heading.
   (should
@@ -3201,12 +3201,12 @@ SCHEDULED: <2017-05-06 Sat>
 	    (progn (org-beginning-of-line) (looking-at-p "Item"))))))
   ;; Leave point before invisible characters at column 0.
   (should
-   (org-test-with-temp-text "[[http://orgmode.org]]<point>"
+   (org-test-with-temp-text "[[https://orgmode.org]]<point>"
      (let ((org-special-ctrl-a/e nil))
        (org-beginning-of-line)
        (bolp))))
   (should
-   (org-test-with-temp-text "[[http://orgmode.org]]<point>"
+   (org-test-with-temp-text "[[https://orgmode.org]]<point>"
      (let ((org-special-ctrl-a/e t))
        (org-beginning-of-line)
        (bolp))))
@@ -3347,7 +3347,7 @@ SCHEDULED: <2017-05-06 Sat>
        (eobp))))
   ;; Get past invisible characters at the end of line.
   (should
-   (org-test-with-temp-text "[[http://orgmode.org]]"
+   (org-test-with-temp-text "[[https://orgmode.org]]"
      (org-end-of-line)
      (eolp))))
 
diff --git a/testing/lisp/test-ox.el b/testing/lisp/test-ox.el
index 1db52c49c..3266a0ccb 100644
--- a/testing/lisp/test-ox.el
+++ b/testing/lisp/test-ox.el
@@ -2843,19 +2843,19 @@ Para2"
   "Test `org-export-insert-image-links' specifications."
   (should-not
    (member "file"
-	   (org-test-with-parsed-data "[[http://orgmode.org][file:image.png]]"
+	   (org-test-with-parsed-data "[[https://orgmode.org][file:image.png]]"
 	     (org-element-map tree 'link
 	       (lambda (l) (org-element-property :type l))))))
   (should
    (member "file"
-	   (org-test-with-parsed-data "[[http://orgmode.org][file:image.png]]"
+	   (org-test-with-parsed-data "[[https://orgmode.org][file:image.png]]"
 	     (org-element-map (org-export-insert-image-links tree info) 'link
 	       (lambda (l) (org-element-property :type l))))))
   ;; Properly set `:parent' property when replace contents with image
   ;; link.
   (should
    (memq 'link
-	 (org-test-with-parsed-data "[[http://orgmode.org][file:image.png]]"
+	 (org-test-with-parsed-data "[[https://orgmode.org][file:image.png]]"
 	   (org-element-map (org-export-insert-image-links tree info) 'link
 	     (lambda (l)
 	       (org-element-type (org-element-property :parent l)))))))
@@ -2863,12 +2863,12 @@ Para2"
   ;; images.
   (should-not
    (member "file"
-	   (org-test-with-parsed-data "[[http://orgmode.org][file:image.xxx]]"
+	   (org-test-with-parsed-data "[[https://orgmode.org][file:image.xxx]]"
 	     (org-element-map (org-export-insert-image-links tree info) 'link
 	       (lambda (l) (org-element-property :type l))))))
   (should
    (member "file"
-	   (org-test-with-parsed-data "[[http://orgmode.org][file:image.xxx]]"
+	   (org-test-with-parsed-data "[[https://orgmode.org][file:image.xxx]]"
 	     (org-element-map
 		 (org-export-insert-image-links tree info '(("file" . "xxx")))
 		 'link
@@ -4427,7 +4427,7 @@ Another text. (ref:text)
   ;; Replace plain links with contents, or with path.
   (should
    (equal "H Org mode\n"
-	  (org-test-with-temp-text "* H [[http://orgmode.org][Org mode]]"
+	  (org-test-with-temp-text "* H [[https://orgmode.org][Org mode]]"
 	    (let (org-export-registered-backends)
 	      (org-export-define-backend 'test
 		'((headline . (lambda (h _c i) (org-export-data-with-backend
@@ -4436,8 +4436,8 @@ Another text. (ref:text)
 					   i)))))
 	      (org-export-as 'test)))))
   (should
-   (equal "H http://orgmode.org\n"
-	  (org-test-with-temp-text "* H [[http://orgmode.org]]"
+   (equal "H https://orgmode.org\n"
+	  (org-test-with-temp-text "* H [[https://orgmode.org]]"
 	    (let (org-export-registered-backends)
 	      (org-export-define-backend 'test
 		'((headline . (lambda (h _c i) (org-export-data-with-backend