diff --git a/ale_linters/markdown/harper.vim b/ale_linters/markdown/harper.vim
new file mode 100644
index 00000000..98e902b3
--- /dev/null
+++ b/ale_linters/markdown/harper.vim
@@ -0,0 +1,32 @@
+" Author: Armand Halbert <armand.halbert@gmail.com>
+" Description: Harper for Markdown files
+
+call ale#Set('markdown_harper_config', {
+\   'harper-ls': {
+\       'diagnosticSeverity': 'hint',
+\       'dialect': 'American',
+\       'linters': {
+\           'SpellCheck': v:true,
+\           'SentenceCapitalization': v:true,
+\           'RepeatedWords': v:true,
+\           'LongSentences': v:true,
+\           'AnA': v:true,
+\           'Spaces': v:true,
+\           'SpelledNumbers': v:false,
+\           'WrongQuotes': v:false,
+\       },
+\   },
+\})
+
+call ale#linter#Define('markdown', {
+\   'name': 'harper',
+\   'lsp': 'stdio',
+\   'executable': 'harper-ls',
+\   'command': '%e --stdio',
+\   'project_root': function('ale_linters#markdown#harper#GetProjectRoot'),
+\   'lsp_config': {b -> ale#Var(b, 'markdown_harper_config')},
+\})
+
+function! ale_linters#markdown#harper#GetProjectRoot(buffer) abort
+    return fnamemodify(bufname(a:buffer), ':p:h')
+endfunction
diff --git a/autoload/ale/lsp.vim b/autoload/ale/lsp.vim
index b0b54c8b..f49f3ae0 100644
--- a/autoload/ale/lsp.vim
+++ b/autoload/ale/lsp.vim
@@ -329,6 +329,27 @@ function! ale#lsp#UpdateConfig(conn_id, buffer, config) abort
     return 1
 endfunction
 
+function! ale#lsp#GetConnectionConfig(conn_id) abort
+    let l:conn = get(s:connections, a:conn_id, {})
+
+    return get(l:conn, 'config', {})
+endfunction
+
+" Send a JSON-RPC response to a server-initiated request (e.g. workspace/configuration).
+" Unlike ale#lsp#Send, which builds outgoing requests/notifications with a 'method' field,
+" this sends a response with 'id' + 'result' fields to reply to a request the server sent us.
+function! ale#lsp#SendResponse(conn_id, id, result) abort
+    let l:conn = get(s:connections, a:conn_id, {})
+
+    if empty(l:conn)
+        return
+    endif
+
+    let l:body = json_encode({'jsonrpc': '2.0', 'id': a:id, 'result': a:result})
+    let l:data = 'Content-Length: ' . strlen(l:body) . "\r\n\r\n" . l:body
+    call s:SendMessageData(l:conn, l:data)
+endfunction
+
 function! ale#lsp#CallInitCallbacks(conn_id) abort
     let l:conn = get(s:connections, a:conn_id, {})
 
diff --git a/autoload/ale/lsp_linter.vim b/autoload/ale/lsp_linter.vim
index 3b3c403c..fae9f709 100644
--- a/autoload/ale/lsp_linter.vim
+++ b/autoload/ale/lsp_linter.vim
@@ -241,6 +241,10 @@ function! ale#lsp_linter#HandleLSPResponse(conn_id, response) abort
         \   : a:response.result.items
 
         call ale#lsp_linter#HandleLSPDiagnostics(a:conn_id, l:uri, l:diagnostics)
+    elseif l:method is# 'workspace/configuration'
+        let l:items = get(get(a:response, 'params', {}), 'items', [])
+        let l:config = ale#lsp#GetConnectionConfig(a:conn_id)
+        call ale#lsp#SendResponse(a:conn_id, a:response.id, map(copy(l:items), 'l:config'))
     elseif l:method is# 'window/showMessage'
         call ale#lsp_window#HandleShowMessage(
         \   s:lsp_linter_map[a:conn_id].name,
diff --git a/doc/ale-markdown.txt b/doc/ale-markdown.txt
index a309f138..7ee577e1 100644
--- a/doc/ale-markdown.txt
+++ b/doc/ale-markdown.txt
@@ -14,6 +14,35 @@ dprint                                                    *ale-markdown-dprint*
 See |ale-dprint-options| and https://dprint.dev/plugins/markdown
 
 
+===============================================================================
+harper                                                    *ale-markdown-harper*
+
+                                           *ale-options.markdown_harper_config*
+                                                  *g:ale_markdown_harper_config*
+                                                  *b:ale_markdown_harper_config*
+markdown_harper_config
+g:ale_markdown_harper_config
+  Type: |Dictionary|
+  Default: `{'harper-ls': {'diagnosticSeverity': 'hint', 'dialect': 'American', ...}}`
+
+  Dictionary passed to harper-ls as LSP workspace configuration. The default
+  enables spell check, sentence capitalization, repeated words, long
+  sentences, a/an errors, and spacing rules, and disables spelled-out numbers
+  and wrong-quote checks.
+
+  Example: >
+    let g:ale_markdown_harper_config = {
+    \   'harper-ls': {
+    \       'diagnosticSeverity': 'warning',
+    \       'linters': {
+    \           'SpellCheck': v:true,
+    \           'LongSentences': v:false,
+    \       },
+    \   },
+    \}
+<
+
+
 ===============================================================================
 markdownlint                                        *ale-markdown-markdownlint*
 
diff --git a/doc/ale-supported-languages-and-tools.txt b/doc/ale-supported-languages-and-tools.txt
index 8cb95b56..fdd8f24d 100644
--- a/doc/ale-supported-languages-and-tools.txt
+++ b/doc/ale-supported-languages-and-tools.txt
@@ -404,6 +404,7 @@ Notes:
 * Markdown
   * `alex`
   * `cspell`
+  * `harper`
   * `languagetool`!!
   * `markdownlint`!!
   * `marksman`
diff --git a/doc/ale.txt b/doc/ale.txt
index 380914bc..e0192177 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -3738,6 +3738,7 @@ documented in additional help files.
   markdown................................|ale-markdown-options|
     cspell................................|ale-markdown-cspell|
     dprint................................|ale-markdown-dprint|
+    harper................................|ale-markdown-harper|
     markdownlint..........................|ale-markdown-markdownlint|
     marksman..............................|ale-markdown-marksman|
     mdl...................................|ale-markdown-mdl|
diff --git a/supported-tools.md b/supported-tools.md
index a038acbd..8988fa72 100644
--- a/supported-tools.md
+++ b/supported-tools.md
@@ -414,6 +414,7 @@ formatting.
 * Markdown
   * [alex](https://github.com/get-alex/alex)
   * [cspell](https://github.com/streetsidesoftware/cspell/tree/main/packages/cspell)
+  * [harper](https://github.com/elijah-potter/harper) :speech_balloon:
   * [languagetool](https://languagetool.org/) :floppy_disk: :speech_balloon:
   * [markdownlint](https://github.com/DavidAnson/markdownlint) :floppy_disk:
   * [marksman](https://github.com/artempyanykh/marksman) :speech_balloon:
diff --git a/test/linter/test_markdown_harper.vader b/test/linter/test_markdown_harper.vader
new file mode 100644
index 00000000..92c1c1b3
--- /dev/null
+++ b/test/linter/test_markdown_harper.vader
@@ -0,0 +1,14 @@
+Before:
+  call ale#assert#SetUpLinterTest('markdown', 'harper')
+
+After:
+  call ale#assert#TearDownLinterTest()
+
+Execute(The default command should be correct):
+  AssertLinter 'harper-ls', ale#Escape('harper-ls') . ' --stdio'
+
+Execute(Should accept configuration settings):
+  AssertLSPConfig g:ale_markdown_harper_config
+
+  let b:ale_markdown_harper_config = {'harper-ls': {'diagnosticSeverity': 'warning'}}
+  AssertLSPConfig {'harper-ls': {'diagnosticSeverity': 'warning'}}
diff --git a/test/lsp/test_engine_lsp_response_handling.vader b/test/lsp/test_engine_lsp_response_handling.vader
index 7b18befc..153be2b0 100644
--- a/test/lsp/test_engine_lsp_response_handling.vader
+++ b/test/lsp/test_engine_lsp_response_handling.vader
@@ -534,6 +534,34 @@ Execute(LSP pull model diagnostic responses that are 'unchanged' should be handl
   \ g:ale_buffer_info[bufnr('')].loclist
   AssertEqual [], g:ale_buffer_info[bufnr('')].active_linter_list
 
+Execute(workspace/configuration requests should be answered with the connection config):
+  let g:sent_responses = []
+
+  function! ale#lsp#GetConnectionConfig(conn_id) abort
+    return {'foo': 'bar'}
+  endfunction
+
+  function! ale#lsp#SendResponse(conn_id, id, result) abort
+    call add(g:sent_responses, [a:conn_id, a:id, a:result])
+  endfunction
+
+  call ale#lsp_linter#SetLSPLinterMap({'1': {'name': 'pylsp', 'aliases': [], 'lsp': 'stdio'}})
+  call ale#lsp_linter#HandleLSPResponse(1, {
+  \ 'jsonrpc': '2.0',
+  \ 'id': 7,
+  \ 'method': 'workspace/configuration',
+  \ 'params': {
+  \   'items': [{'section': 'foo'}, {'section': 'bar'}],
+  \ },
+  \})
+
+  AssertEqual
+  \ [[1, 7, [{'foo': 'bar'}, {'foo': 'bar'}]]],
+  \ g:sent_responses
+
+  unlet! g:sent_responses
+  runtime autoload/ale/lsp.vim
+
 Execute(LSP errors should be logged in the history):
   call ale#lsp_linter#SetLSPLinterMap({'347': {'name': 'foobar', 'aliases': [], 'lsp': 'stdio'}})
   call ale#lsp_linter#HandleLSPResponse(347, {
diff --git a/test/lsp/test_update_config.vader b/test/lsp/test_update_config.vader
index 2a2c85e6..75a9a37a 100644
--- a/test/lsp/test_update_config.vader
+++ b/test/lsp/test_update_config.vader
@@ -1,16 +1,26 @@
 Before:
   runtime autoload/ale/lsp.vim
+  runtime autoload/ale/job.vim
 
   let g:conn_id = ale#lsp#Register('executable', '/foo/bar', '', {})
+  let g:sent_data = []
 
-  " Stub out this function, so we test updating configs.
+  " Stub out these functions to capture calls without side effects.
   function! ale#lsp#Send(conn_id, message) abort
   endfunction
 
+  function! ale#job#SendRaw(job_id, data) abort
+    call add(g:sent_data, a:data)
+  endfunction
+
 After:
   Restore
 
   unlet! g:conn_id
+  unlet! g:conn
+  unlet! g:sent_data
+  unlet! g:remainder
+  unlet! g:messages
 
   runtime autoload/ale/lsp.vim
 
@@ -19,3 +29,27 @@ Execute(Only send updates when the configuration dictionary changes):
   AssertEqual 1, ale#lsp#UpdateConfig(g:conn_id, bufnr(''), {'a': 1})
   AssertEqual 0, ale#lsp#UpdateConfig(g:conn_id, bufnr(''), {'a': 1})
   AssertEqual 1, ale#lsp#UpdateConfig(g:conn_id, bufnr(''), {})
+
+Execute(ale#lsp#GetConnectionConfig() should return empty dict for unknown connections):
+  AssertEqual {}, ale#lsp#GetConnectionConfig('unknown:conn')
+
+Execute(ale#lsp#GetConnectionConfig() should return the current connection config):
+  call ale#lsp#UpdateConfig(g:conn_id, bufnr(''), {'foo': 'bar'})
+  AssertEqual {'foo': 'bar'}, ale#lsp#GetConnectionConfig(g:conn_id)
+
+Execute(ale#lsp#SendResponse() should do nothing for unknown connections):
+  " Should not throw
+  call ale#lsp#SendResponse('unknown:conn', 1, [])
+  AssertEqual [], g:sent_data
+
+Execute(ale#lsp#SendResponse() should send a JSON-RPC response message):
+  " Give the connection a job_id so s:SendMessageData routes to ale#job#SendRaw
+  let g:conn = ale#lsp#GetConnections()[g:conn_id]
+  let g:conn.job_id = 1
+
+  call ale#lsp#SendResponse(g:conn_id, 42, ['result_value'])
+
+  AssertEqual 1, len(g:sent_data)
+  let [g:remainder, g:messages] = ale#lsp#ReadMessageData(g:sent_data[0])
+  AssertEqual '', g:remainder
+  AssertEqual [{'jsonrpc': '2.0', 'id': 42, 'result': ['result_value']}], g:messages