List of Online Code Checkers

We’ve all been there. There’s that one task you’ve been avoiding on your todo list. It’s not even that hard, to be honest. It just involves something finicky, fiddly, and unfamiliar. Maybe it’s a particularly tricky regex or a shell script that needs written. Luckily, it’s the 21st century and there are a plethora of resources to aid coders in these tasks. May I present The Big List of Online Code Checkers:

Devops Stuff

mod_rewrite Rules:
Shell Scripts:
SPF Record:
Subnet Calculator:

Runners up – local devops tools for checking syntax

Apache: apachectl configtest
Bind: named-checkconf /etc/named.conf
Nginx: nginx -t -c conf/nginx.conf
Postfix: postfix check
SSH: sshd -t – Use this every time if you don’t want to get locked out :)

Coding Playgrounds

These are great for spiking on a solution in a less-familiar language.

Collaborative Editor:
Regular Expressions:

Online Code Checkers, Formatters & Converters

CSS validator:
HAML to ERB converter:
HTML Tidy:
HTML validator:
Javascript Minifier:
JSON validator/formatter:
RSS/Atom validator:


robots.txt: Google Webmaster Tools
Structured Data:
XML Sitemap Generator:

This is just a small sampling of what’s available. There are online code checkers, validators, converters, formatters, and generators for just about anything you can imagine. Next time you find yourself with a dreaded task in

What online code checkers, formatters, or generators do you use on a regular basis?

About Alexander

Alexander has been programming for a very long time. When he met Ruby, it was love at first sight.
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