diff --git a/.github/workflows/generate.yml b/.github/workflows/generate.yml
index 5f743f2a0..feb00e8d1 100644
--- a/.github/workflows/generate.yml
+++ b/.github/workflows/generate.yml
@@ -81,7 +81,7 @@ jobs:
         run: |
           cd work
           # Create html documents
-          make html
+          make -j4 html2
 
           cd ..
       - name: Lock mutex
diff --git a/Makefile b/Makefile
index cf726c639..823424165 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,10 @@
+SRC_JAX := $(wildcard doc/*.jax vim_faq/*.jax)
+OUT_JAX := $(addprefix target/html/doc/,$(notdir $(SRC_JAX)))
+TAGS_JAX := target/html/doc/tags.jax
+HTML := $(OUT_JAX:.jax=.html) $(TAGS_JAX:.jax=.html)
+
 .PHONY: all check replace html clean
+.PHONY: html2 tags
 
 all:
 
@@ -15,5 +21,25 @@ html:
 	cp doc/*.jax vim_faq/*.jax target/html/doc
 	-cd target/html/doc ; vim -eu ../../../tools/buildhtml.vim -c "qall!"
 
+html2: $(HTML)
+
+tags: $(TAGS_JAX)
+
+target/html/doc/%.jax: doc/%.jax
+	-@mkdir -p target/html/doc
+	cp $< $@
+
+target/html/doc/%.jax: vim_faq/%.jax
+	-@mkdir -p target/html/doc
+	cp $< $@
+
+$(TAGS_JAX): $(OUT_JAX)
+	rm -f $@
+	-cd target/html/doc ; vim -eu ../../../tools/build_tag.vim -c "qall!"
+
+target/html/doc/%.html: target/html/doc/%.jax $(TAGS_JAX)
+	-@mkdir -p target/html/doc
+	-cd target/html/doc ; vim -eu ../../../tools/build_html.vim $(notdir $(<F)) $(notdir $@) -c "qall!"
+
 clean:
 	rm -rf target
diff --git a/tools/build_html.vim b/tools/build_html.vim
new file mode 100644
index 000000000..382a4a88a
--- /dev/null
+++ b/tools/build_html.vim
@@ -0,0 +1,68 @@
+set nocompatible
+set nomore
+set encoding=utf-8
+set fileencodings=utf-8
+syntax on
+colorscheme delek
+let g:html_no_progress = 1
+
+if has('windows') && !has('gui_running')
+  set t_ti=
+endif
+
+enew!
+
+source <sfile>:h/tag_aliases.vim
+source <sfile>:h/untranslated.vim
+source <sfile>:h/makehtml.vim
+
+let s:tools_dir = expand('<sfile>:p:h')
+let s:proj_dir = expand('<sfile>:p:h:h')
+
+function! s:main()
+  " for the lastest help syntax
+  let &runtimepath = s:tools_dir . ',' . &runtimepath
+  " for ja custom syntax
+  let &runtimepath .= ',' . s:proj_dir
+  if argc() != 2
+    echoerr "require two arguments"
+    finish
+  endif
+  call s:BuildHtml(argv(0), argv(1))
+endfunction
+
+function! s:BuildHtml(src, dst)
+  call MakeHtml2(a:src, a:dst, 1)
+  call s:ToJekyll(a:dst)
+endfunction
+
+function! s:ToJekyll(file)
+  set nomodeline
+  execute "edit! " . a:file
+  set fileformat=unix
+
+  let helpname = expand('%:t:r')
+  if helpname == 'index'
+    let helpname = 'help'
+  endif
+
+  " remove header
+  silent 1,/^<hr>/delete _
+  " remove footer
+  silent /^<hr>/,$delete _
+
+  " escape jekyll tags
+  silent %s/{\{2,}\|{%/{{ "\0" }}/ge
+
+  " YAML front matter
+  call append(0, [
+        \ '---',
+        \ 'layout: vimdoc',
+        \ printf("helpname: '%s'", helpname),
+        \ '---',
+        \ ])
+
+  update!
+endfunction
+
+call s:main()
diff --git a/tools/build_tag.vim b/tools/build_tag.vim
new file mode 100644
index 000000000..2559d0561
--- /dev/null
+++ b/tools/build_tag.vim
@@ -0,0 +1,40 @@
+set nocompatible
+set nomore
+set encoding=utf-8
+set fileencodings=utf-8
+syntax on
+colorscheme delek
+let g:html_no_progress = 1
+
+if has('windows') && !has('gui_running')
+  set t_ti=
+endif
+
+enew!
+
+source <sfile>:h/tag_aliases.vim
+source <sfile>:h/untranslated.vim
+source <sfile>:h/makehtml.vim
+
+let s:tools_dir = expand('<sfile>:p:h')
+let s:proj_dir = expand('<sfile>:p:h:h')
+
+function! s:main()
+  " for the lastest help syntax
+  let &runtimepath = s:tools_dir . ',' . &runtimepath
+  " for ja custom syntax
+  let &runtimepath .= ',' . s:proj_dir
+  call s:BuildTag()
+endfunction
+
+function! s:BuildTag()
+  " generate tags
+  try
+    helptags .
+  catch
+    echo v:exception
+  endtry
+  call MakeTagsFile()
+endfunction
+
+call s:main()
diff --git a/tools/makehtml.vim b/tools/makehtml.vim
index 2d3f8fb9e..8c394dc27 100644
--- a/tools/makehtml.vim
+++ b/tools/makehtml.vim
@@ -38,6 +38,10 @@ function! MakeHtmlAll(...)
   endif
 endfunction
 
+function! s:JsonName(lang)
+  return a:lang == "" ? "tags.json" : printf("tags-%s.json", a:lang)
+endfunction
+
 function! MakeTagsFile()
   let files = split(glob('tags'), '\n')
   let files += split(glob('tags-??'), '\n')
@@ -50,7 +54,7 @@ function! MakeTagsFile()
     endif
     silent new `=fname`
     silent %delete _
-    let tags = s:GetTags(lang)
+    let tags = s:LoadTags(lang)
     for tagname in sort(keys(tags))
       if tagname == "help-tags"
         continue
@@ -60,6 +64,8 @@ function! MakeTagsFile()
     call append('$', ' vim:ft=help:')
     silent 1delete _
     silent wq!
+    " save JSON tag cache
+    call writefile([js_encode(tags)], s:JsonName(lang), "s")
   endfor
 endfunction
 
@@ -216,26 +222,36 @@ endfunction
 
 function! s:GetTags(lang)
   if !exists("s:tags_" . a:lang)
-    let &l:tags = (a:lang == "") ? "./tags" : "./tags-" . a:lang
-    let tags = {}
-    for item in taglist(".*")
-      let item["html"] = s:HtmlName(item["filename"])
-      let tags[item["name"]] = item
-    endfor
-    " for help-tags
-    let item = {}
-    let item["name"] = "help-tags"
-    if s:IsSingleMode()
-      let item["html"] = "tags.html"
+    " try to load JSON tag cache
+    let jsonname = s:JsonName(a:lang)
+    if filereadable(jsonname)
+      let s:tags_{a:lang} = js_decode(readfile(jsonname)[0])
     else
-      let item["html"] = printf("tags%s.html", (a:lang == "") ? "" : "." . a:lang)
+      let s:tags_{a:lang} = s:LoadTags(a:lang)
     endif
-    let tags[item["name"]] = item
-    let s:tags_{a:lang} = tags
   endif
   return s:tags_{a:lang}
 endfunction
 
+func s:LoadTags(lang)
+  let &l:tags = (a:lang == "") ? "./tags" : "./tags-" . a:lang
+  let tags = {}
+  for item in taglist(".*")
+    let item["html"] = s:HtmlName(item["filename"])
+    let tags[item["name"]] = item
+  endfor
+  " for help-tags
+  let item = {}
+  let item["name"] = "help-tags"
+  if s:IsSingleMode()
+    let item["html"] = "tags.html"
+  else
+    let item["html"] = printf("tags%s.html", (a:lang == "") ? "" : "." . a:lang)
+  endif
+  let tags[item["name"]] = item
+  return tags
+endfunction
+
 function! s:IsSingleMode()
   " if there is one language files, do not append language identifier
   " (use "help.html" instead of "help.ab.html").