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New: File Converter

Convert files locally — including Word and Excel.

Images, whole PDFs, Word DOCX, Excel XLSX, text, code, CSV and JSON stay on your device. KitLumo never receives or stores a copy.

PDF · Word · Excel · Images

Free Design tools

Aspect Ratio

Straightforward tools that work right here on your phone, tablet or computer. No account, no AI, no nonsense.

Your tool data stays on this device. Anything you type, paste, calculate or open in a tool is not sent to us. KitLumo does not receive it or save a copy.
141 free tools Browser-first No account

Free Design tools

How to use the Aspect Ratio

Scale image or video dimensions without changing proportions. Add the information requested by the tool and review the result before you copy, download or use it.

  1. Enter or choose the information requested by the tool.
  2. Check the result and change an input if you want to compare another scenario.
  3. Copy, download or use the result when it fits your task.

Using the result

Use the result as a design starting point, then check it in the real interface and at the actual screen sizes you support.

Your tool entries are handled in your browser and are not sent to or saved by KitLumo.

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Practical guides

Understand the result, not just the number.

Short, plain-language guides explain the assumptions, privacy and limits behind the most important KitLumo tools.

View all guides
PDF to WordWhat text reflow preserves PDF to ExcelHow pages become worksheets Mortgage paymentsWhat the estimate includes Percentage changeWhich formula answers the question Unit conversionHow to check measurements Calculator checklistHow to check a result

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Colour Converter

Switch between HEX, RGB and HSL colour values.

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Contrast Checker

Check contrast ratios and text readability against WCAG levels.

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Aspect Ratio

Scale image or video dimensions without changing proportions.

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CSS Gradient Generator

Create a two-colour gradient and copy its CSS.

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Box Shadow Generator

Adjust a shadow visually and copy the CSS declaration.

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Border Radius Generator

Shape rounded corners and copy the CSS radius value.

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CSS Grid Generator

Create a simple responsive grid declaration and copy the CSS.

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Tool workspace

Word Counter

Help shape KitLumo

Don’t see what you need?

Tell us the task you are trying to solve. The most-requested tools guide what we build next.

How KitLumo stays free

Supported by ads. Helped by people.

Clearly labelled ads fund the website so everyone can use every tool for free. If KitLumo saves you time, you are also welcome to make an optional donation to help pay for hosting and keep the tools available.

Donating never unlocks extra features. Every tool remains free for everyone.
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How it works

Free means free.

KitLumo is built around small, focused utilities. No login walls, no artificial limits and no AI layer where a reliable tool will do.

Every tool currently available works directly on the phone, tablet or computer you are using. Anything you type, paste, calculate or open in a tool is not sent to us, and KitLumo does not save a copy.

Your saved and recently used tool shortcuts are stored only in your browser on this device. When you use “Report a problem” or “Request a free tool,” only that message and any email address you choose to add are sent to KitLumo.

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