Are there any good free barcode scripts or plugins for Illustrator?

For anyone landing here looking for a free route: you don't strictly need a plugin. Generate the barcode as an SVG and place it in Illustrator:

1. Generate the code (EAN-13, UPC-A or Code 128) as SVG with a free generator.
2. In Illustrator, use File > Place (or open the SVG and copy it in). It comes in as vector paths, so it scales cleanly.
3. Scale proportionally only. Don't stretch the width on its own, because that changes the bar ratios. Keep the quiet zone (white margin) on both sides.
4. Check the human-readable digits match the encoded number, and that the EAN/UPC check digit is correct.
5. Print a proof at the final size and test-scan it with a real scanner or phone app before production. Screen checks aren't enough.

Avoid barcode fonts for print work, as was mentioned in another thread. Generated vector paths are more reliable.

(Disclosure: I run Pixel Print Co. Our free Barcode Generator makes Code 128, EAN-13 and UPC-A as SVG or PNG, runs in the browser, and needs no sign-up: https://pixelprintco.ca/tools/barcode-generator/)

If you miss how simple Barcode Toolbox was, try Vectode. It's a panel for Illustrator 2020+ built to work the same easy way: pick the code type, type the number, click, and the barcode is placed in your document as editable vector paths.

It covers EAN-13/8, UPC-A/E, Data Matrix, GS1 DataMatrix, Aztec and pharma codes (PPN, SÚKL), and handles GS1 sizing, quiet zones and bar width reduction for you.

https://exchange.adobe.com/apps/cc/205507/vectode

(Disclosure: I'm the developer. It's not free, but it's a one-time purchase, no subscription. Happy to help here if you get stuck.)

I found an new extension that works in Adobe illustrator, photoshop and InDesign at once 

Support all barcodes

CODE128 (with automatic mode switching and forced mode A/B/C), EAN-13, EAN-8, EAN-5, EAN-2, UPC-A, UPC-E, CODE39, ITF (including ITF-14), MSI (including MSI10, MSI11, MSI1010, and MSI1110), Pharmacode, and Codabar. Export your barcodes in multiple file types, including SVG, JPG, PNG, WebP, ai and indd

It just cost 20 usd for lifetime

https://youtu.be/XIIfmVIU-hA

I think it's a good deal

It can be found https://www.allbarcodegenerator.com/

try this extension by Ten A, this is for QRcode but he also has a barcode extension

https://exchange.adobe.com/creativecloud.details.107.html