diff --git a/bookindex.md b/bookindex.md
index 6a54a8508d..a21fca78d7 100644
--- a/bookindex.md
+++ b/bookindex.md
@@ -207,6 +207,9 @@
  - GOPHER: [How it started](project/started.md#how-it-started), [What protocols does curl support?](protocols/protocols.md#what-protocols-does-curl-support), [GOPHER](protocols/curl.md#gopher), [Supported schemes](cmdline/urls/scheme.md#supported-schemes), [Version](usingcurl/version.md#version), [Variables](internals/tests/file-format.md#variables)
  - GOPHERS: [What protocols does curl support?](protocols/protocols.md#what-protocols-does-curl-support), [GOPHERS](protocols/curl.md#gophers), [Supported schemes](cmdline/urls/scheme.md#supported-schemes), [Variables](internals/tests/file-format.md#variables)
 ## H
+ - haproxy: [haproxy](usingcurl/proxies/haproxy.md#haproxy), [All options](libcurl/options/all.md#all-options)
+ - --haproxy-clientip: [curl and haproxy](usingcurl/proxies/haproxy.md#curl-and-haproxy)
+ - --haproxy-protocol: [curl and haproxy](usingcurl/proxies/haproxy.md#curl-and-haproxy)
  - --header: [Server differences](usingcurl/downloads/browsers.md#server-differences), [Proxy headers](usingcurl/proxies/headers.md#proxy-headers), [JSON](http/post/json.md#json), [Customize headers](http/modify/headers.md#customize-headers)
  - Header callback: [All options](libcurl/options/all.md#all-options), [Header data](libcurl/callbacks/header.md#header-data), [Response body](libcurl-http/responses.md#response-body), [Download headers too](libcurl-http/download.md#download-headers-too)
  - homebrew: [macOS](get/macos.md#macos)
@@ -234,8 +237,8 @@
  - Indentation: [Indentation](source/style.md#indentation)
  - IPFS: [Using curl](usingcurl.md#using-curl), [IPFS](usingcurl/ipfs.md#ipfs)
  - --ipfs-gateway: [Gateway](usingcurl/ipfs.md#gateway)
- - IPv4: [Host](cmdline/urls/host.md#host), [Port number](cmdline/urls/port.md#port-number), [Available --write-out variables](usingcurl/verbose/writeout.md#available---write-out-variables), [All options](libcurl/options/all.md#all-options), [Name resolving](libcurl/conn/names.md#name-resolving), [`host*.c` sources](internals/resolving.md#host-c-sources), [Variables](internals/tests/file-format.md#variables)
- - IPv6: [Host](cmdline/urls/host.md#host), [Port number](cmdline/urls/port.md#port-number), [URL globbing](cmdline/globbing.md#url-globbing), [Available --write-out variables](usingcurl/verbose/writeout.md#available---write-out-variables), [Version](usingcurl/version.md#version), [SOCKS proxy](usingcurl/proxies/socks.md#socks-proxy), [All options](libcurl/options/all.md#all-options), [Name resolving](libcurl/conn/names.md#name-resolving), [Zone ID](libcurl/url/get-part.md#zone-id), [`CURLRES_IPV6`](internals/resolving.md#curlres_ipv6), [Variables](internals/tests/file-format.md#variables)
+ - IPv4: [Host](cmdline/urls/host.md#host), [Port number](cmdline/urls/port.md#port-number), [Available --write-out variables](usingcurl/verbose/writeout.md#available---write-out-variables), [curl and haproxy](usingcurl/proxies/haproxy.md#curl-and-haproxy), [All options](libcurl/options/all.md#all-options), [Name resolving](libcurl/conn/names.md#name-resolving), [`host*.c` sources](internals/resolving.md#host-c-sources), [Variables](internals/tests/file-format.md#variables)
+ - IPv6: [Host](cmdline/urls/host.md#host), [Port number](cmdline/urls/port.md#port-number), [URL globbing](cmdline/globbing.md#url-globbing), [Available --write-out variables](usingcurl/verbose/writeout.md#available---write-out-variables), [Version](usingcurl/version.md#version), [SOCKS proxy](usingcurl/proxies/socks.md#socks-proxy), [curl and haproxy](usingcurl/proxies/haproxy.md#curl-and-haproxy), [All options](libcurl/options/all.md#all-options), [Name resolving](libcurl/conn/names.md#name-resolving), [Zone ID](libcurl/url/get-part.md#zone-id), [`CURLRES_IPV6`](internals/resolving.md#curlres_ipv6), [Variables](internals/tests/file-format.md#variables)
  - IRC: [How it started](project/started.md#how-it-started), [Project communication](project/comm.md#project-communication)
 ## J
  - JavaScript: [Client differences](usingcurl/downloads/browsers.md#client-differences), [PAC](usingcurl/proxies/pac.md#pac), [HTTP POST](http/post.md#http-post), [JavaScript and forms](http/post/javascript.md#javascript-and-forms), [JavaScript redirects](http/redirects.md#javascript-redirects), [Figure out what the browser does](http/browserlike.md#figure-out-what-the-browser-does)
@@ -297,7 +300,7 @@
  - Progress callback: [All options](libcurl/options/all.md#all-options), [timer_callback](libcurl/drive/multi-socket.md#timer_callback), [Progress information](libcurl/callbacks/progress.md#progress-information), [Transfer control](libcurl/control.md#transfer-control), [easy API](libcurl/control/stop.md#easy-api), [Progress callback](libcurl/control/progress-callback.md#progress-callback)
  - pronunciation: [Pronunciation](project/name.md#pronunciation)
  - --proxy: [HTTP proxy](usingcurl/proxies/http.md#http-proxy), [Authentication](http/auth.md#authentication)
- - proxy: [How it started](project/started.md#how-it-started), [Available --write-out variables](usingcurl/verbose/writeout.md#available---write-out-variables), [Line 4: Features](usingcurl/version.md#line-4-features), [Intermediaries' fiddlings](usingcurl/downloads/browsers.md#intermediaries-fiddlings), [Proxies](usingcurl/proxies.md#proxies), [Discover your proxy](usingcurl/proxies/discover.md#discover-your-proxy), [PAC](usingcurl/proxies/pac.md#pac), [Proxy type](usingcurl/proxies/type.md#proxy-type), [HTTP proxy](usingcurl/proxies/http.md#http-proxy), [SOCKS proxy](usingcurl/proxies/socks.md#socks-proxy), [MITM proxy](usingcurl/proxies/mitm.md#mitm-proxy), [Proxy authentication](usingcurl/proxies/auth.md#proxy-authentication), [HTTPS proxy](usingcurl/proxies/https.md#https-proxy), [Proxy environment variables](usingcurl/proxies/env.md#proxy-environment-variables), [Proxy headers](usingcurl/proxies/headers.md#proxy-headers), [Available exit codes](usingcurl/returns.md#available-exit-codes), [CONNECT response codes](http/response.md#connect-response-codes), [Authentication](http/auth.md#authentication), [Verification](libcurl/options/tls.md#verification), [All options](libcurl/options/all.md#all-options), [Proxies](libcurl/conn/proxies.md#proxies), [Available information](libcurl/getinfo.md#available-information), [HTTP proxy](libcurl-http.md#http-proxy), [Header origins](libcurl-http/headerapi.md#header-origins), [Variables](internals/tests/file-format.md#variables)
+ - proxy: [How it started](project/started.md#how-it-started), [Available --write-out variables](usingcurl/verbose/writeout.md#available---write-out-variables), [Line 4: Features](usingcurl/version.md#line-4-features), [Intermediaries' fiddlings](usingcurl/downloads/browsers.md#intermediaries-fiddlings), [Proxies](usingcurl/proxies.md#proxies), [Discover your proxy](usingcurl/proxies/discover.md#discover-your-proxy), [PAC](usingcurl/proxies/pac.md#pac), [Proxy type](usingcurl/proxies/type.md#proxy-type), [HTTP proxy](usingcurl/proxies/http.md#http-proxy), [SOCKS proxy](usingcurl/proxies/socks.md#socks-proxy), [MITM proxy](usingcurl/proxies/mitm.md#mitm-proxy), [Proxy authentication](usingcurl/proxies/auth.md#proxy-authentication), [HTTPS proxy](usingcurl/proxies/https.md#https-proxy), [Proxy environment variables](usingcurl/proxies/env.md#proxy-environment-variables), [Proxy headers](usingcurl/proxies/headers.md#proxy-headers), [haproxy](usingcurl/proxies/haproxy.md#haproxy), [Available exit codes](usingcurl/returns.md#available-exit-codes), [CONNECT response codes](http/response.md#connect-response-codes), [Authentication](http/auth.md#authentication), [Verification](libcurl/options/tls.md#verification), [All options](libcurl/options/all.md#all-options), [Proxies](libcurl/conn/proxies.md#proxies), [Available information](libcurl/getinfo.md#available-information), [HTTP proxy](libcurl-http.md#http-proxy), [Header origins](libcurl-http/headerapi.md#header-origins), [Variables](internals/tests/file-format.md#variables)
  - --proxy-http2: [HTTP/2](usingcurl/proxies/https.md#http-2)
  - --proxy-user: [Proxy authentication](usingcurl/proxies/auth.md#proxy-authentication), [Authentication](http/auth.md#authentication)
  - --proxy1.0: [HTTP proxy tunneling](usingcurl/proxies/http.md#http-proxy-tunneling)