Unit Converter
Convert units of measurement.
OpenDays between two dates. - runs entirely in your browser. Free, fast and private.
Select the first day of the interval.
Select the last day to measure through.
Total days, weeks, and approximate months appear.
Use the duration for project planning or contracts.
Date Difference is a free math & calculators utility on OneDevToolkit. Days between two dates. It runs in your browser for this session - use the workspace on this page to try it.
Need a related step? Open the Math & Calculators hub at /math-tools/ or the <a href="/blog/">blog</a> for longer workflows.
Processes data instantly with no server round-trips.
Your data never leaves your browser. Nothing is uploaded.
Works in any modern browser. Nothing to download or install.
No limits, no sign-up, no credit card required.
Works on desktop, tablet and mobile devices.
Beautiful in both themes. Your preference is saved.
Keyboard shortcut
Open Date Difference when you need a quick result without uploading data to a third-party site.
No install required - bookmark the tool and return anytime.
Client-side processing keeps inputs on your device for core OneDevToolkit tools.
Answers for this tool. For site-wide help, open the FAQ hub.
Date Difference helps you days between two dates. instantly in the browser.
Yes - modern browsers handle Unicode strings. Some case transforms behave differently for locale-specific characters.
Most text tools preserve line structure unless the operation is specifically about wrapping, sorting, or joining lines.
No artificial server quota. Extremely large pastes may slow the tab - split the text if needed.
Use Clear and re-paste, or keep the original in another tab. Browser undo may work inside the textarea.
Processing is local. Avoid pasting secrets into any website if your policy forbids it - prefer offline editors for credentials.
Use Copy on the toolbar or select the output panel. Download is available when the tool exposes a file export.
Treat markup as plain text unless the tool is specifically a Markdown/HTML utility. Preview elsewhere if rendering matters.
Paste from Notes/email, run Date Difference, then copy back. Long documents are easier on desktop.
Browse Math & Calculators for case converters, counters, diff, and cleanup tools.