Diff Checker: a small tool that solves a specific problem

Code reviews, configuration changes, and debugging sessions demand precise understanding of what changed between two versions of text. Manual comparison of large blocks of code or configuration files is error-prone, and version control diffs don’t always provide a quick, focused view for sharing or verifying changes outside a repository. What it is Diff Checker is a browser-based text comparison tool that performs line-by-line analysis of two text blocks and highlights differences with color-coded visual indicators. It processes text entirely in the browser—part of the 200+ free tools on DevTools—meaning no data is uploaded or stored, a privacy‑first design. The interface uses a split‑pane layout: original text on the left, modified text on the right. As you paste or type, the comparison engine recalculates the diff in real time, marking added, removed, and changed segments so differences are immediately clear. Several configuration options tailor the analysis. Toggling whitespace sensitivity ignores differences in indentation or blank lines, useful when comparing code from teams with different formatting conventions. Case sensitivity can be turned off for text where capitalization inconsistencies are irrelevant. A swap button reverses the comparison direction with a single click, handy when the assignment of “original” and “modified” is accidentally reversed. How to use it Paste the original text into the left panel and the modified version into the right panel. The diff view updates instantly, so you don’t need to press a button to see changes. For code, the process is straightforward. Drop a baseline function on the left: function calculateTotal ( items ) { let total = 0 ; for ( let item of items ) { total += item . price ; } return total ; } And the updated version on the right: function calculateTotal ( items , taxRate = 0 ) { let total = 0 ; for ( let item of items ) { total += item . price * ( 1 + taxRate ); } return Math . round ( total * 100 ) / 100 ; } The