How to use a curl formatter to help diagnose slow websites

Introduction

The following guide explains how you can use curl to gain more insight into how long it takes for a website to load.

Procedure

1. Copy the formatter file to your computer from here:

https://gist.github.com/manifestinteractive/ce8dec10dcb4725b8513

2. Run the following command with the domain that you need to test:

curl -L -w"@sniff.txt" -s -o /dev/null https://exampledomain.tld

Here is an example of what it looks like:

➜ ~ curl -L -w"@sniff.txt" -s -o /dev/null https://google.com

============= HOST: ==========

local_ip: 127.0.0.1
local_port: 50273
remote_ip: 172.217.14.164
remote_port: 443

======= CONNECTION: ==========

http_version: 2
http_code: 200
http_connect: 000
num_connects: 2
num_redirects: 1
redirect_url:

============= FILE: ==========

content_type: text/html; charset=ISO-8859-1
filename_effective: /dev/null
ftp_entry_path:
size_download: 12888
size_header: 1347
size_request: 148
size_upload: 0
speed_download: 29335.000
speed_upload: 0.000
ssl_verify_result: 0
url_effective: https://www.google.com/

=== TIME BREAKDOWN: ==========

time_appconnect: 0.198221
time_connect: 0.033181
time_namelookup: 0.032625
time_pretransfer: 0.198500
time_redirect: 0.175495
time_starttransfer: 0.261832
----------
time_total: 0.439332

You can read about what the various timings mean on the Curl Man Page:

https://curl.se/docs/manpage.html