diff --git a/autoload/ale/completion.vim b/autoload/ale/completion.vim
new file mode 100644
index 0000000..f6862db
--- /dev/null
+++ b/autoload/ale/completion.vim
@@ -0,0 +1,192 @@
+" Author: w0rp <devw0rp@gmail.com>
+" Description: Completion support for LSP linters
+
+let s:timer = -1
+let s:delay = 300
+let s:max_suggestions = 20
+let s:buffer_completion_map = {}
+
+function! s:RememberCompletionInfo(buffer, executable, request_id, line, column) abort
+    let s:buffer_completion_map[a:buffer] = {
+    \   'executable': a:executable,
+    \   'request_id': a:request_id,
+    \   'line': a:line,
+    \   'column': a:column,
+    \}
+endfunction
+
+" Find completion information for a response, and delete the information
+" if the request failed.
+function! s:FindCompletionInfo(response) abort
+    let l:matched_buffer = -1
+    let l:matched_data = {}
+
+    for l:key in keys(s:buffer_completion_map)
+        let l:obj = s:buffer_completion_map[l:key]
+
+        if l:obj.request_id ==# a:response.request_seq
+            if get(a:response, 'success')
+                let l:matched_buffer = str2nr(l:key)
+                let l:matched_data = l:obj
+            else
+                " Clean up the data we remembered if the request failed.
+                call remove(s:buffer_completion_map, l:matched_buffer)
+            endif
+        endif
+    endfor
+
+    return [l:matched_buffer, l:matched_data]
+endfunction
+
+function! s:HandleCompletions(response) abort
+    let [l:buffer, l:info] = s:FindCompletionInfo(a:response)
+
+    if l:buffer >= 0
+        let l:names = []
+
+        for l:suggestion in a:response.body[: s:max_suggestions]
+            call add(l:names, l:suggestion.name)
+        endfor
+
+        let l:request_id = ale#lsp#SendMessageToProgram(
+        \   l:info.executable,
+        \   ale#lsp#tsserver_message#CompletionEntryDetails(
+        \       l:buffer,
+        \       l:info.line,
+        \       l:info.column,
+        \       l:names,
+        \   ),
+        \)
+
+        if l:request_id
+            let l:info.request_id = l:request_id
+        else
+            " Remove the info now if we failed to start the request.
+            call remove(s:buffer_completion_map, l:buffer)
+        endif
+    endif
+endfunction
+
+function! s:HandleCompletionDetails(response) abort
+    let [l:buffer, l:info] = s:FindCompletionInfo(a:response)
+
+    if l:buffer >= 0
+        call remove(s:buffer_completion_map, l:buffer)
+
+        let l:name_list = []
+
+        for l:suggestion in a:response.body[: s:max_suggestions]
+            " Each suggestion has 'kind' and 'kindModifier' properties
+            " which could be useful.
+            " Each one of these parts has 'kind' properties
+            let l:displayParts = []
+
+            for l:part in l:suggestion.displayParts
+                call add(l:displayParts, l:part.text)
+            endfor
+
+            " Each one of these parts has 'kind' properties
+            let l:documentationParts = []
+
+            for l:part in l:suggestion.documentation
+                call add(l:documentationParts, l:part.text)
+            endfor
+
+            let l:text = l:suggestion.name
+            \   . ' - '
+            \   . join(l:displayParts, '')
+            \   . (!empty(l:documentationParts) ? ' ' : '')
+            \   . join(l:documentationParts, '')
+
+            call add(l:name_list, l:text)
+        endfor
+
+        echom string(l:name_list)
+    endif
+endfunction
+
+function! s:HandleLSPResponse(response) abort
+    let l:command = get(a:response, 'command', '')
+
+    if l:command ==# 'completions'
+        call s:HandleCompletions(a:response)
+    elseif l:command ==# 'completionEntryDetails'
+        call s:HandleCompletionDetails(a:response)
+    endif
+endfunction
+
+function! s:GetCompletionsForTSServer(buffer, linter, line, column) abort
+    let l:executable = has_key(a:linter, 'executable_callback')
+    \   ? ale#util#GetFunction(a:linter.executable_callback)(a:buffer)
+    \   : a:linter.executable
+    let l:command = l:executable
+
+    let l:job_id = ale#lsp#StartProgram(
+    \   l:executable,
+    \   l:executable,
+    \   function('s:HandleLSPResponse')
+    \)
+
+    if !l:job_id
+        if g:ale_history_enabled
+            call ale#history#Add(a:buffer, 'failed', l:job_id, l:command)
+        endif
+    endif
+
+    if ale#lsp#OpenTSServerDocumentIfNeeded(l:executable, a:buffer)
+        if g:ale_history_enabled
+            call ale#history#Add(a:buffer, 'started', l:job_id, l:command)
+        endif
+    endif
+
+    call ale#lsp#SendMessageToProgram(
+    \   l:executable,
+    \   ale#lsp#tsserver_message#Change(a:buffer),
+    \)
+
+    let l:request_id = ale#lsp#SendMessageToProgram(
+    \   l:executable,
+    \   ale#lsp#tsserver_message#Completions(a:buffer, a:line, a:column),
+    \)
+
+    if l:request_id
+        call s:RememberCompletionInfo(
+        \   a:buffer,
+        \   l:executable,
+        \   l:request_id,
+        \   a:line,
+        \   a:column,
+        \)
+    endif
+endfunction
+
+function! ale#completion#GetCompletions() abort
+    let l:buffer = bufnr('')
+    let [l:line, l:column] = getcurpos()[1:2]
+
+    for l:linter in ale#linter#Get(getbufvar(l:buffer, '&filetype'))
+        if l:linter.lsp ==# 'tsserver'
+            call s:GetCompletionsForTSServer(l:buffer, l:linter, l:line, l:column)
+        endif
+    endfor
+endfunction
+
+function! s:TimerHandler(...) abort
+    call ale#completion#GetCompletions()
+endfunction
+
+function! ale#completion#Queue() abort
+    if s:timer != -1
+        call timer_stop(s:timer)
+        let s:timer = -1
+    endif
+
+    let s:timer = timer_start(s:delay, function('s:TimerHandler'))
+endfunction
+
+function! ale#completion#Start() abort
+    augroup ALECompletionGroup
+        autocmd!
+        autocmd TextChangedI * call ale#completion#Queue()
+    augroup END
+endfunction
diff --git a/autoload/ale/engine.vim b/autoload/ale/engine.vim
index f7c25b0..b56558f 100644
--- a/autoload/ale/engine.vim
+++ b/autoload/ale/engine.vim
@@ -42,7 +42,6 @@ function! ale#engine#InitBufferInfo(buffer) abort
         \   'temporary_file_list': [],
         \   'temporary_directory_list': [],
         \   'history': [],
-        \   'open_lsp_documents': [],
         \}
     endif
 endfunction
@@ -563,8 +562,6 @@ endfunction
 
 function! s:CheckWithTSServer(buffer, linter, executable) abort
     let l:info = g:ale_buffer_info[a:buffer]
-    let l:open_documents = l:info.open_lsp_documents
-    let l:is_open = index(l:open_documents, a:linter.name) >= 0
 
     let l:command = ale#job#PrepareCommand(a:executable)
     let l:job_id = ale#lsp#StartProgram(a:executable, l:command, function('s:HandleLSPResponse'))
@@ -577,16 +574,10 @@ function! s:CheckWithTSServer(buffer, linter, executable) abort
         return
     endif
 
-    if !l:is_open
+    if ale#lsp#OpenTSServerDocumentIfNeeded(a:executable, a:buffer)
         if g:ale_history_enabled
             call ale#history#Add(a:buffer, 'started', l:job_id, l:command)
         endif
-
-        call add(l:open_documents, a:linter.name)
-        call ale#lsp#SendMessageToProgram(
-        \   a:executable,
-        \   ale#lsp#tsserver_message#Open(a:buffer),
-        \)
     endif
 
     call ale#lsp#SendMessageToProgram(
diff --git a/autoload/ale/lsp.vim b/autoload/ale/lsp.vim
index ce7efd1..1f63904 100644
--- a/autoload/ale/lsp.vim
+++ b/autoload/ale/lsp.vim
@@ -16,6 +16,7 @@ function! s:NewConnection() abort
     \   'address': '',
     \   'executable': '',
     \   'job_id': -1,
+    \   'open_documents': [],
     \}
 
     call add(s:connections, l:conn)
@@ -283,3 +284,21 @@ function! ale#lsp#SendMessageToAddress(address, message) abort
 
     return l:id == 0 ? -1 : l:id
 endfunction
+
+function! ale#lsp#OpenTSServerDocumentIfNeeded(executable, buffer) abort
+    let l:opened = 0
+    let l:matches = filter(s:connections[:], 'v:val.executable ==# a:executable')
+
+    " Send the command for opening the document only if needed.
+    if !empty(l:matches) && index(l:matches[0].open_documents, a:buffer) < 0
+        call ale#lsp#SendMessageToProgram(
+        \   a:executable,
+        \   ale#lsp#tsserver_message#Open(a:buffer),
+        \)
+        call add(l:matches[0].open_documents, a:buffer)
+
+        let l:opened = 1
+    endif
+
+    return l:opened
+endfunction
diff --git a/autoload/ale/lsp/tsserver_message.vim b/autoload/ale/lsp/tsserver_message.vim
index e78b29e..2ccbf75 100644
--- a/autoload/ale/lsp/tsserver_message.vim
+++ b/autoload/ale/lsp/tsserver_message.vim
@@ -26,7 +26,7 @@ function! ale#lsp#tsserver_message#Change(buffer) abort
     \   'file': expand('#' . a:buffer . ':p'),
     \   'line': 1,
     \   'offset': 1,
-    \   'endLine': 1073741824 ,
+    \   'endLine': 1073741824,
     \   'endOffset': 1,
     \   'insertString': join(l:lines, "\n"),
     \}]
@@ -35,3 +35,21 @@ endfunction
 function! ale#lsp#tsserver_message#Geterr(buffer) abort
     return [1, 'ts@geterr', {'files': [expand('#' . a:buffer . ':p')]}]
 endfunction
+
+function! ale#lsp#tsserver_message#Completions(buffer, line, column) abort
+    " An optional 'prefix' key can be added here for a completion prefix.
+    return [0, 'ts@completions', {
+    \   'line': a:line,
+    \   'offset': a:column,
+    \   'file': expand('#' . a:buffer . ':p'),
+    \}]
+endfunction
+
+function! ale#lsp#tsserver_message#CompletionEntryDetails(buffer, line, column, entry_names) abort
+    return [0, 'ts@completionEntryDetails', {
+    \   'line': a:line,
+    \   'offset': a:column,
+    \   'file': expand('#' . a:buffer . ':p'),
+    \   'entryNames': a:entry_names,
+    \}]
+endfunction
diff --git a/test/lsp/test_lsp_client_messages.vader b/test/lsp/test_lsp_client_messages.vader
index 5decbf6..3b5c64f 100644
--- a/test/lsp/test_lsp_client_messages.vader
+++ b/test/lsp/test_lsp_client_messages.vader
@@ -146,3 +146,34 @@ Execute(ale#lsp#tsserver_message#Geterr() should return correct messages):
   \   }
   \ ],
   \ ale#lsp#tsserver_message#Geterr(bufnr(''))
+
+Execute(ale#lsp#tsserver_message#Completions() should return correct messages):
+  silent! noautocmd file foo.ts
+
+  AssertEqual
+  \ [
+  \   0,
+  \   'ts@completions',
+  \   {
+  \     'file': b:dir . '/foo.ts',
+  \     'line': 347,
+  \     'offset': 12,
+  \   }
+  \ ],
+  \ ale#lsp#tsserver_message#Completions(bufnr(''), 347, 12)
+
+Execute(ale#lsp#tsserver_message#CompletionEntryDetails() should return correct messages):
+  silent! noautocmd file foo.ts
+
+  AssertEqual
+  \ [
+  \   0,
+  \   'ts@completionEntryDetails',
+  \   {
+  \     'file': b:dir . '/foo.ts',
+  \     'line': 347,
+  \     'offset': 12,
+  \     'entryNames': ['foo', 'bar'],
+  \   }
+  \ ],
+  \ ale#lsp#tsserver_message#CompletionEntryDetails(bufnr(''), 347, 12, ['foo', 'bar'])