Code 39 Generator

Create Code 39 barcodes as SVG from uppercase alphanumeric text.

freeworks offlinenothing uploaded
Input
Output
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About code 39 generator

Code 39 Generator needs nothing from a server once the page has loaded. Leave it open on a train with no signal and it carries on.

Your input goes into a function and the result comes back out, both inside this tab. There is no round trip and no third party in the middle.

You will find it under Barcodes, alongside 8 other tools for the same sort of job.

Supports custom dimensions, text visibility, and narrow/wide bar ratio.

How to use it

01
Start it
Every control is on the tool itself. Keyboard shortcuts, where there are any, are listed beside it.
02
Watch it run
It updates in the page as you go. Nothing is sent anywhere, so it keeps working with the network off.
03
Close when done
Nothing is stored between visits. Reloading gives you a clean start rather than picking up where you left off.

Examples

Inventory Label
Generate a Code 39 barcode for inventory tracking
Input
text: ITEM-001
height: 80
showText: true
Output
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 360 110" width="360" height="110"><rect width="360" height="110" fill="white"/><rect x="20" y="5" width="2" height="80" fill="black"/><rect x="28" y="5" width="2" height="80" fill="black"/><rect x="32" y="5" width="6" height="80" fill="black"/><rect x="40" y="5" width="6" height="80" fill="black"/><rect x="48" y="5" width="2" height="80" fill="black"/><rect x="52" y="5" width="2" height="80" fill="black"/><rect x="56" y="5" width="6" height="80" fill="black"/><rect x="64" y="5" width="2" height="80" fill="black"/><rect x="72" y="5" width="6" height="80" fill="black"/><rect x="80" y="5" width="2" height="80" fill="black"/><rect x="84" y="5"…

Questions

Does Code 39 Generator work offline?+

Yes. It is JavaScript running in this tab, so once the page has loaded it needs nothing further from the network. Put the machine in flight mode and it carries on. Nothing you do here is sent anywhere, because there is nowhere for it to go.

Does it remember anything between visits?+

No. Reload the page and it starts from nothing. There is no account, no saved state and no cookie holding your last session. That is a deliberate trade: it cannot lose your data because it never keeps any.

Is it accurate?+

Timing comes from performance.now(), the high resolution clock the browser provides, rather than from setInterval, which drifts by a few milliseconds every tick and compounds over minutes. What can still shift things is the browser throttling a tab in the background, so leave it visible if the timing matters.

Does it make a sound?+

Where a sound makes sense, it is generated with the Web Audio API rather than loaded as a file, so there is nothing to download and nothing to block. Browsers refuse to start audio until you have interacted with the page, which is why the first press is what switches it on.

Can I use Code 39 Generator on a phone?+

Yes. The controls are sized for touch and the layout collapses to one column on a narrow screen. Bear in mind that a phone locking its screen will suspend the page, and timing stops with it.