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CSS Flexbox Generator — Visual Layout Builder

Generate flexbox CSS with live preview: control direction, justify-content, align-items, flex-wrap, and gap. Learn how axes swap between row and column.

No limitsZero data leaksSuper fast
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display: flex;
flex-direction: row;
justify-content: flex-start;
align-items: stretch;
flex-wrap: nowrap;
gap: 8px;

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About this tool

Justify-content and align-items swap axes when you change flex-direction

Most developers memorize one rule: justify-content aligns items horizontally, align-items aligns them vertically. This works for flex-direction: row. Then they switch to flex-direction: column, apply the same properties, and nothing moves where they expect. The properties didn't change meaning—but the main axis did.

justify-content always aligns along the main axis. In a row layout, that's horizontal. In a column layout, it's vertical. The same justify-content: center declaration centers items left-to-right in a row, but top-to-bottom in a column. align-items governs the cross axis, which is perpendicular to the main axis—vertical in a row, horizontal in a column. Flip the direction, and both properties flip their visual effect.

Flex-wrap and gap work together to prevent overflow and control spacing

flex-wrap: nowrap (the default) forces all items onto a single line, shrinking them if necessary. flex-wrap: wrap breaks items onto multiple lines when they run out of space. Set gap to add uniform spacing between items—horizontally in a row, vertically in a column, and both dimensions when items wrap. This tool lets you adjust gap from 0 to 48 pixels and see the preview update in real time.

Row-reverse and column-reverse flip the visual order without changing the DOM

flex-direction: row-reverse lays items out horizontally from right to left. flex-direction: column-reverse stacks them vertically from bottom to top. The HTML source order never changes—only the visual rendering flips. This is useful for responsive layouts where you want to reorder content on mobile without altering the DOM.

Flex shorthand properties on individual children are out of scope here

This tool controls the flex container's behavior: display: flex, flex-direction, justify-content, align-items, flex-wrap, and gap. It does not manage flex-grow, flex-shrink, or flex-basis on individual items, nor does it generate Grid layouts. For fine-grained control over how each child grows or shrinks, write those properties by hand in your CSS.

See also: Gradient Text Generator and Glassmorphism Generator.

How to use the CSS Flexbox Generator

Takes about a minute. No signup, no download, your data stays in your browser.

  1. 1
    Open the tool. Scroll up to the CSS Flexbox Generator above — it loads instantly in your browser, no install needed.
  2. 2
    Enter your values. The fields come pre-filled with realistic defaults so you can see how it works — replace them with your own numbers.
  3. 3
    Read the result. The output updates instantly. Copy or share it — nothing is uploaded to a server, everything stays on your device.

Frequently asked questions

Common questions about the CSS Flexbox Generator.

Why does justify-content move items vertically when I use flex-direction: column?

In a column layout, flex-direction defines the main axis as vertical. justify-content always aligns along the main axis, so it moves items vertically. align-items, which controls the cross axis, now moves items horizontally instead. The properties' effects swap because the axes swap.

What does flex-wrap: wrap do, and how does gap interact with it?

flex-wrap: wrap allows items to break onto a new line (or column) when they run out of space. Without wrap, items shrink to fit. gap adds uniform spacing between items in both directions—horizontally and vertically between rows when wrapping is enabled. You can adjust gap from 0 to 48 pixels and see the effect instantly in the preview.

When should I use space-between instead of space-around or space-evenly?

space-between puts equal space between items but no space at the edges—useful for navigation bars or button groups where you want the first and last items to touch the container edges. space-around adds half that space on the edges. space-evenly distributes space equally, including edges. Test each in the preview to see which fits your layout.

How many items can I preview at once?

The tool allows you to adjust the preview from 1 to 8 items using a slider. This range covers most common flex layout scenarios—a single item, a button group, a navigation bar, or a small grid of cards. For layouts with more items, the CSS you copy will scale to any number of children.

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