# Coding Challenge #125 - Online Diff Viewer

DevFeed: [Coding Challenge #125 - Online Diff Viewer](<https://devfeed.tech/articles/coding-challenge-125-online-diff-viewer-29201.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-125-online-diff>)

Author: John Crickett

Published: 2026-07-04T08:01:27Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [coding](<https://devfeed.tech/topics/coding.md>), [web applications](<https://devfeed.tech/topics/web-applications.md>), [Algorithm](<https://devfeed.tech/topics/algorithm.md>), [Accessibility](<https://devfeed.tech/topics/accessibility.md>), [Syntax Highlighting](<https://devfeed.tech/topics/syntax-highlighting.md>), [navigation](<https://devfeed.tech/topics/navigation.md>), [CSS](<https://devfeed.tech/topics/css.md>), [HTML](<https://devfeed.tech/topics/html.md>), [JavaScript](<https://devfeed.tech/topics/javascript.md>)

Tags: [accessibility](<https://devfeed.tech/tags/accessibility.md>), [algorithm](<https://devfeed.tech/tags/algorithm.md>), [browser](<https://devfeed.tech/tags/browser.md>), [build](<https://devfeed.tech/tags/build.md>), [code](<https://devfeed.tech/tags/code.md>), [coding](<https://devfeed.tech/tags/coding.md>), [css](<https://devfeed.tech/tags/css.md>), [html](<https://devfeed.tech/tags/html.md>), [javascript](<https://devfeed.tech/tags/javascript.md>), [navigation](<https://devfeed.tech/tags/navigation.md>), [syntax-highlighting](<https://devfeed.tech/tags/syntax-highlighting.md>)

## AI overview

Coding Challenge #125 asks readers to build an online diff viewer in the browser. The project compares two text inputs, computes a line-level diff, and presents additions, deletions, and unchanged lines, with planned features including multiple views, syntax highlighting, navigation, export, and accessibility.

## Source excerpt

This challenge is to build your own online diff viewer.