Useful Code Comparing Tools for Web Developers

Developers of many different languages all share the same growing pains. Buggy source codes will be a nagging problem throughout a developer’s career but a much less-considered issue is in the compiling and the merging of edits from two or more copies of the same source. Luckily there are incredibly helpful tools available for just this type of situation.

In looking for software tools to use for code comparisons, you’ll run into a lot of different solutions. Both Windows and Mac OSX have their own free and paid tools, along with a web application which runs universally on all systems.

1. Diffuse

The Diffuse software is free to download through SourceForge. They offer installation codes for Linux, Win32, Mac OS X and FreeBSD. Each of the operating systems has support for command line prompts and a GUI-based window toolkit.

Depending on how you like to work, the command line does speed things up considerably, but only if you know what you’re doing! To keep things simple, you may want to stick to basic GUI. Their site has a couple of screenshots you can check out along with a list of features. These include line-by-line comparison and detailed code highlighting.

Linux OS support Diffuse

What I really like about Diffuse is the open source nature of the project. You do not need to pay anything to gain full access to the power of their software suite. This may be the most globally accepted, among the major OS, free tool used for comparing code files. If you have the time, check out their online manual, which can help clear up any questions you’ve got. Of course, you can always download and install the app to get a hands-on experience.

2. DiffMerge

Another great product DiffMerge has been put out there by a software company named SourceGear. Their software is also supported among all major operating systems, and they also feature a set of tools for comparing lines of code.

Mac OS X screenshot for DiffMerge files

Inside the DiffMerge screenshot gallery, you’ll find examples of the program running in Windows, Mac and Linux environments. In each example it’s clear how the buttons and toolbars have been created and placed together simplisticly. With this suite you’re not just limited to single file comparisons, but actually allowed to piece together entire folders of code! You can compare two project source folders side-by-side with relative ease. The added function of highlighting code differences in multiple panes makes DiffMerge all the more valuable.

DiffMerge is 100% free to download. If you check out their downloads page, you can pick from dozens of installer solutions. I have to admit that for a free tool this program really blows away the competition!

3. Active File Compare

The development company Formula Software has put out a Microsoft Windows-specific tool used for professional code comparison and version management. It’s called Active File Compare which targets programmers using slightly more complicated languages such as C++/C#, Java, Visual Basic, and Ruby. Code highlighting is supported for base web languages such as HTML and PHP.

Macbook closeup detail photograph

Unfortunately this software is offered free only in a trial version. The cheapest license costs $10 for personal or $15 for businesses. This pricing chart is fairly reasonable, especially considering you are locked in for free updates for life, with no recurring charges.

One feature which really stands out is the ability to compare between Microsoft Office documents. Specifically, Excel spreadsheets are difficult to merge together when you need to switch between many tabs and sheets. The AFC software will keep a history of your changes so that you can revert to any point without losing previous data. You can lump these changes together into projects which behave like a small-scale version control system.

Active File Compare merging files

If you’re constantly working in higher-level development languages then I suggest giving AFC a chance. It features a GUI similar tp the other solutions, along with basic command line options. Yet the ability to import and compare Excel spreadsheets easily justifies the licensing cost.

4. Kaleidoscope App

With the Windows solutions we’ve introduced, we can’t leave Mac users in the cold. Kaleidoscope has been on the scene for a few years and has been featured in plenty of web design galleries. The app is free to download for a 30-day trial then charges a $29 purchase fee (about $39 USD) if you would want the app to keep.

mac os x kaleidascope

I have to say this is one of the more expensive solutions for code comparison tools. Nonetheless, you shouldn’t expect otherwise for a Mac application, and of course, their standards for design are impeccable. Even the app website itself is brilliantly designed!

homepage of kaleidascope os x app

Some of the added features include an instant search bar, customizable code highlights, keyboard shortcuts, and support for the most popular versions of control systems. Git, SubVersion and Mercurial are the 3 highest rated among the many options. And you can even tie into third party applications such as Gitbox or Tower Git client.

But the most unique and surprising feature is the ability to compare differences between images! These include file types such as .png and .jpg, and Kaleidoscope even supports dynamic files such as PSD and AI. Yes you read that correctly — this app can compare code files and layered images all from within the same interface! Talk about some impressive development skills. It seems like $40USD is actually a bargain for a software with all these features.

5. WinMerge

For one more desktop solution I’d like to present WinMerge. They have been in development since June 2009 and now offers the software 100% free for download. Support includes all versions of Windows 98 to Vista/7 and has both 32-bit and 64-bit installers.

WinMerge home page website

The software comes standard with all the features you’d expect to find when comparing your source files. Distinct line numbers, code highlighting, tabbed interface, file merging, etc. You can read a bit more on their personal website which also includes some nifty screenshots and installation instructions. The online manual also goes over some of the basic FAQ beginners are likely to run into.

There isn’t any specific calling card to make you choose WinMerge over another solution. It’s not to say this software isn’t worth trying; some Windows users may prefer it over other options. Many of the features have been well documented by the programmers over years of development — and you can’t go wrong with free GNU tools.

6. Compare my Files

This website is no longer in service.

Here is the only browser-based web app I’ve used for comparing different bits of code. Compare my Files is a simple and free online utility. You can use the tool to parse through the codes of two different files to highlight differences. You can also choose to compare the codes line-by-line to gather more accurate results if the files are very similar.

The biggest downside here is that you’re limited to only uploading two files at a time. Bear in mind that almost any of the desktop alternatives would provide a better interface to managing detailed code differences. Of course, for a web application this is still fairly impressive. I feel that Compare my Files is your best option when you are working on another computer without any pre-installed code-comparing tool to use.

compare my files web app

This app is also handy as a quick check-in system to ensure that your files match up. I’ve found myself in this position when downloading different .zip archives from a cloud system, where I’m not 100% sure which files have been edited. The upload tools only support plaintext source code, but the content language is entirely unrelated as far as the parsing engine is concerned. Give it a try and you may be pleasantly surprised at how intuitive this browser-based solution feels with regards to other software.


If you’ve been building software or web projects for a while then you can understand how difficult managing these files can become. The process of merging different source code can be very annoying and risky to boot but as you become accustomed to the workflow you’ll be able to shave off hours of working time.

I hope these tools can get you interested in managing your code and keeping directory files up-to-date. If you have other examples or wish to share your thoughts please do so in the discussion area below.

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