Best Free Online Developer Tools to Use in 2026
A practical, opinionated list of the best free online developer tools worth using in 2026, organized by category so you can find what you need fast.
Aug 08, 2026
CSS Flexbox Generator
Create and customize CSS Flexbox layouts visually. Configure direction, wrap, alignment, gap, and item order with a live preview.
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Preview
Flex items are numbered for reference
What is CSS Flexbox?
CSS Flexbox (Flexible Box Layout) is a one-dimensional layout system that distributes space along a single axis. It gives you powerful control over alignment, direction, order, and sizing of elements within a container.
This tool features:
- Real-time preview — See the flex layout update instantly as you adjust controls.
- Full Flexbox control — Configure direction, wrap, alignment, content distribution, and gap.
- Visual item display — Flex items are numbered and color-coded for easy reference.
- Copy HTML & CSS — Export both the HTML structure and CSS code with one click.
CSS Flexbox Properties
| Property | Description | Example |
|---|---|---|
flex-direction |
Defines the main axis direction | row |
flex-wrap |
Controls whether items wrap to a new line | wrap |
justify-content |
Aligns items along the main axis | center |
align-items |
Aligns items along the cross axis | center |
align-content |
Aligns multi-line flex lines along the cross axis | space-between |
gap |
Sets the gap between flex items | 8px |
How to Use
- Set the flex properties — Choose direction, wrap, and alignment options from the dropdowns.
- Customize spacing and sizing — Adjust gap, item count, and item width using the sliders.
- Preview the layout — See how items behave with different flex properties in real time.
- Copy the code — Click Copy HTML or Copy CSS to export your flex layout.
Frequently Asked Questions
What is the difference between justify-content and align-items?
justify-content aligns items along the main axis (horizontal in a row layout), while align-items aligns items along the cross axis (vertical in a row layout). In a column layout, these axes are swapped.
When should I use Flexbox vs Grid?
Use Flexbox for one-dimensional layouts (single row or column). Use CSS Grid for two-dimensional layouts (rows AND columns). Flexbox excels at distributing space and aligning content along a single axis.
Is this tool free to use?
Yes. All processing happens entirely in your browser. No data is sent to any server.
Last updated: 17 Aug 2026
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